Source

pgdevel / src / backend / optimizer / prep / prepjointree.c

Full commit
   1
   2
   3
   4
   5
   6
   7
   8
   9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  21
  22
  23
  24
  25
  26
  27
  28
  29
  30
  31
  32
  33
  34
  35
  36
  37
  38
  39
  40
  41
  42
  43
  44
  45
  46
  47
  48
  49
  50
  51
  52
  53
  54
  55
  56
  57
  58
  59
  60
  61
  62
  63
  64
  65
  66
  67
  68
  69
  70
  71
  72
  73
  74
  75
  76
  77
  78
  79
  80
  81
  82
  83
  84
  85
  86
  87
  88
  89
  90
  91
  92
  93
  94
  95
  96
  97
  98
  99
 100
 101
 102
 103
 104
 105
 106
 107
 108
 109
 110
 111
 112
 113
 114
 115
 116
 117
 118
 119
 120
 121
 122
 123
 124
 125
 126
 127
 128
 129
 130
 131
 132
 133
 134
 135
 136
 137
 138
 139
 140
 141
 142
 143
 144
 145
 146
 147
 148
 149
 150
 151
 152
 153
 154
 155
 156
 157
 158
 159
 160
 161
 162
 163
 164
 165
 166
 167
 168
 169
 170
 171
 172
 173
 174
 175
 176
 177
 178
 179
 180
 181
 182
 183
 184
 185
 186
 187
 188
 189
 190
 191
 192
 193
 194
 195
 196
 197
 198
 199
 200
 201
 202
 203
 204
 205
 206
 207
 208
 209
 210
 211
 212
 213
 214
 215
 216
 217
 218
 219
 220
 221
 222
 223
 224
 225
 226
 227
 228
 229
 230
 231
 232
 233
 234
 235
 236
 237
 238
 239
 240
 241
 242
 243
 244
 245
 246
 247
 248
 249
 250
 251
 252
 253
 254
 255
 256
 257
 258
 259
 260
 261
 262
 263
 264
 265
 266
 267
 268
 269
 270
 271
 272
 273
 274
 275
 276
 277
 278
 279
 280
 281
 282
 283
 284
 285
 286
 287
 288
 289
 290
 291
 292
 293
 294
 295
 296
 297
 298
 299
 300
 301
 302
 303
 304
 305
 306
 307
 308
 309
 310
 311
 312
 313
 314
 315
 316
 317
 318
 319
 320
 321
 322
 323
 324
 325
 326
 327
 328
 329
 330
 331
 332
 333
 334
 335
 336
 337
 338
 339
 340
 341
 342
 343
 344
 345
 346
 347
 348
 349
 350
 351
 352
 353
 354
 355
 356
 357
 358
 359
 360
 361
 362
 363
 364
 365
 366
 367
 368
 369
 370
 371
 372
 373
 374
 375
 376
 377
 378
 379
 380
 381
 382
 383
 384
 385
 386
 387
 388
 389
 390
 391
 392
 393
 394
 395
 396
 397
 398
 399
 400
 401
 402
 403
 404
 405
 406
 407
 408
 409
 410
 411
 412
 413
 414
 415
 416
 417
 418
 419
 420
 421
 422
 423
 424
 425
 426
 427
 428
 429
 430
 431
 432
 433
 434
 435
 436
 437
 438
 439
 440
 441
 442
 443
 444
 445
 446
 447
 448
 449
 450
 451
 452
 453
 454
 455
 456
 457
 458
 459
 460
 461
 462
 463
 464
 465
 466
 467
 468
 469
 470
 471
 472
 473
 474
 475
 476
 477
 478
 479
 480
 481
 482
 483
 484
 485
 486
 487
 488
 489
 490
 491
 492
 493
 494
 495
 496
 497
 498
 499
 500
 501
 502
 503
 504
 505
 506
 507
 508
 509
 510
 511
 512
 513
 514
 515
 516
 517
 518
 519
 520
 521
 522
 523
 524
 525
 526
 527
 528
 529
 530
 531
 532
 533
 534
 535
 536
 537
 538
 539
 540
 541
 542
 543
 544
 545
 546
 547
 548
 549
 550
 551
 552
 553
 554
 555
 556
 557
 558
 559
 560
 561
 562
 563
 564
 565
 566
 567
 568
 569
 570
 571
 572
 573
 574
 575
 576
 577
 578
 579
 580
 581
 582
 583
 584
 585
 586
 587
 588
 589
 590
 591
 592
 593
 594
 595
 596
 597
 598
 599
 600
 601
 602
 603
 604
 605
 606
 607
 608
 609
 610
 611
 612
 613
 614
 615
 616
 617
 618
 619
 620
 621
 622
 623
 624
 625
 626
 627
 628
 629
 630
 631
 632
 633
 634
 635
 636
 637
 638
 639
 640
 641
 642
 643
 644
 645
 646
 647
 648
 649
 650
 651
 652
 653
 654
 655
 656
 657
 658
 659
 660
 661
 662
 663
 664
 665
 666
 667
 668
 669
 670
 671
 672
 673
 674
 675
 676
 677
 678
 679
 680
 681
 682
 683
 684
 685
 686
 687
 688
 689
 690
 691
 692
 693
 694
 695
 696
 697
 698
 699
 700
 701
 702
 703
 704
 705
 706
 707
 708
 709
 710
 711
 712
 713
 714
 715
 716
 717
 718
 719
 720
 721
 722
 723
 724
 725
 726
 727
 728
 729
 730
 731
 732
 733
 734
 735
 736
 737
 738
 739
 740
 741
 742
 743
 744
 745
 746
 747
 748
 749
 750
 751
 752
 753
 754
 755
 756
 757
 758
 759
 760
 761
 762
 763
 764
 765
 766
 767
 768
 769
 770
 771
 772
 773
 774
 775
 776
 777
 778
 779
 780
 781
 782
 783
 784
 785
 786
 787
 788
 789
 790
 791
 792
 793
 794
 795
 796
 797
 798
 799
 800
 801
 802
 803
 804
 805
 806
 807
 808
 809
 810
 811
 812
 813
 814
 815
 816
 817
 818
 819
 820
 821
 822
 823
 824
 825
 826
 827
 828
 829
 830
 831
 832
 833
 834
 835
 836
 837
 838
 839
 840
 841
 842
 843
 844
 845
 846
 847
 848
 849
 850
 851
 852
 853
 854
 855
 856
 857
 858
 859
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
/*-------------------------------------------------------------------------
 *
 * prepjointree.c
 *	  Planner preprocessing for subqueries and join tree manipulation.
 *
 * NOTE: the intended sequence for invoking these operations is
 *		pull_up_sublinks
 *		inline_set_returning_functions
 *		pull_up_subqueries
 *		flatten_simple_union_all
 *		do expression preprocessing (including flattening JOIN alias vars)
 *		reduce_outer_joins
 *
 *
 * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  src/backend/optimizer/prep/prepjointree.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "catalog/pg_type.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/clauses.h"
#include "optimizer/placeholder.h"
#include "optimizer/prep.h"
#include "optimizer/subselect.h"
#include "optimizer/tlist.h"
#include "parser/parse_relation.h"
#include "parser/parsetree.h"
#include "rewrite/rewriteManip.h"


typedef struct pullup_replace_vars_context
{
	PlannerInfo *root;
	List	   *targetlist;		/* tlist of subquery being pulled up */
	RangeTblEntry *target_rte;	/* RTE of subquery */
	bool	   *outer_hasSubLinks;		/* -> outer query's hasSubLinks */
	int			varno;			/* varno of subquery */
	bool		need_phvs;		/* do we need PlaceHolderVars? */
	bool		wrap_non_vars;	/* do we need 'em on *all* non-Vars? */
	Node	  **rv_cache;		/* cache for results with PHVs */
} pullup_replace_vars_context;

typedef struct reduce_outer_joins_state
{
	Relids		relids;			/* base relids within this subtree */
	bool		contains_outer; /* does subtree contain outer join(s)? */
	List	   *sub_states;		/* List of states for subtree components */
} reduce_outer_joins_state;

static Node *pull_up_sublinks_jointree_recurse(PlannerInfo *root, Node *jtnode,
								  Relids *relids);
static Node *pull_up_sublinks_qual_recurse(PlannerInfo *root, Node *node,
							  Node **jtlink1, Relids available_rels1,
							  Node **jtlink2, Relids available_rels2);
static Node *pull_up_subqueries_recurse(PlannerInfo *root, Node *jtnode,
						   JoinExpr *lowest_outer_join,
						   JoinExpr *lowest_nulling_outer_join,
						   AppendRelInfo *containing_appendrel);
static Node *pull_up_simple_subquery(PlannerInfo *root, Node *jtnode,
						RangeTblEntry *rte,
						JoinExpr *lowest_outer_join,
						JoinExpr *lowest_nulling_outer_join,
						AppendRelInfo *containing_appendrel);
static Node *pull_up_simple_union_all(PlannerInfo *root, Node *jtnode,
						 RangeTblEntry *rte);
static void pull_up_union_leaf_queries(Node *setOp, PlannerInfo *root,
						   int parentRTindex, Query *setOpQuery,
						   int childRToffset);
static void make_setop_translation_list(Query *query, Index newvarno,
							List **translated_vars);
static bool is_simple_subquery(Query *subquery, RangeTblEntry *rte,
				   JoinExpr *lowest_outer_join);
static bool is_simple_union_all(Query *subquery);
static bool is_simple_union_all_recurse(Node *setOp, Query *setOpQuery,
							List *colTypes);
static bool is_safe_append_member(Query *subquery);
static void replace_vars_in_jointree(Node *jtnode,
						 pullup_replace_vars_context *context,
						 JoinExpr *lowest_nulling_outer_join);
static Node *pullup_replace_vars(Node *expr,
					pullup_replace_vars_context *context);
static Node *pullup_replace_vars_callback(Var *var,
							 replace_rte_variables_context *context);
static Query *pullup_replace_vars_subquery(Query *query,
							 pullup_replace_vars_context *context);
static reduce_outer_joins_state *reduce_outer_joins_pass1(Node *jtnode);
static void reduce_outer_joins_pass2(Node *jtnode,
						 reduce_outer_joins_state *state,
						 PlannerInfo *root,
						 Relids nonnullable_rels,
						 List *nonnullable_vars,
						 List *forced_null_vars);
static void substitute_multiple_relids(Node *node,
						   int varno, Relids subrelids);
static void fix_append_rel_relids(List *append_rel_list, int varno,
					  Relids subrelids);
static Node *find_jointree_node_for_rel(Node *jtnode, int relid);


/*
 * pull_up_sublinks
 *		Attempt to pull up ANY and EXISTS SubLinks to be treated as
 *		semijoins or anti-semijoins.
 *
 * A clause "foo op ANY (sub-SELECT)" can be processed by pulling the
 * sub-SELECT up to become a rangetable entry and treating the implied
 * comparisons as quals of a semijoin.	However, this optimization *only*
 * works at the top level of WHERE or a JOIN/ON clause, because we cannot
 * distinguish whether the ANY ought to return FALSE or NULL in cases
 * involving NULL inputs.  Also, in an outer join's ON clause we can only
 * do this if the sublink is degenerate (ie, references only the nullable
 * side of the join).  In that case it is legal to push the semijoin
 * down into the nullable side of the join.  If the sublink references any
 * nonnullable-side variables then it would have to be evaluated as part
 * of the outer join, which makes things way too complicated.
 *
 * Under similar conditions, EXISTS and NOT EXISTS clauses can be handled
 * by pulling up the sub-SELECT and creating a semijoin or anti-semijoin.
 *
 * This routine searches for such clauses and does the necessary parsetree
 * transformations if any are found.
 *
 * This routine has to run before preprocess_expression(), so the quals
 * clauses are not yet reduced to implicit-AND format.	That means we need
 * to recursively search through explicit AND clauses, which are
 * probably only binary ANDs.  We stop as soon as we hit a non-AND item.
 */
void
pull_up_sublinks(PlannerInfo *root)
{
	Node	   *jtnode;
	Relids		relids;

	/* Begin recursion through the jointree */
	jtnode = pull_up_sublinks_jointree_recurse(root,
											   (Node *) root->parse->jointree,
											   &relids);

	/*
	 * root->parse->jointree must always be a FromExpr, so insert a dummy one
	 * if we got a bare RangeTblRef or JoinExpr out of the recursion.
	 */
	if (IsA(jtnode, FromExpr))
		root->parse->jointree = (FromExpr *) jtnode;
	else
		root->parse->jointree = makeFromExpr(list_make1(jtnode), NULL);
}

/*
 * Recurse through jointree nodes for pull_up_sublinks()
 *
 * In addition to returning the possibly-modified jointree node, we return
 * a relids set of the contained rels into *relids.
 */
static Node *
pull_up_sublinks_jointree_recurse(PlannerInfo *root, Node *jtnode,
								  Relids *relids)
{
	if (jtnode == NULL)
	{
		*relids = NULL;
	}
	else if (IsA(jtnode, RangeTblRef))
	{
		int			varno = ((RangeTblRef *) jtnode)->rtindex;

		*relids = bms_make_singleton(varno);
		/* jtnode is returned unmodified */
	}
	else if (IsA(jtnode, FromExpr))
	{
		FromExpr   *f = (FromExpr *) jtnode;
		List	   *newfromlist = NIL;
		Relids		frelids = NULL;
		FromExpr   *newf;
		Node	   *jtlink;
		ListCell   *l;

		/* First, recurse to process children and collect their relids */
		foreach(l, f->fromlist)
		{
			Node	   *newchild;
			Relids		childrelids;

			newchild = pull_up_sublinks_jointree_recurse(root,
														 lfirst(l),
														 &childrelids);
			newfromlist = lappend(newfromlist, newchild);
			frelids = bms_join(frelids, childrelids);
		}
		/* Build the replacement FromExpr; no quals yet */
		newf = makeFromExpr(newfromlist, NULL);
		/* Set up a link representing the rebuilt jointree */
		jtlink = (Node *) newf;
		/* Now process qual --- all children are available for use */
		newf->quals = pull_up_sublinks_qual_recurse(root, f->quals,
													&jtlink, frelids,
													NULL, NULL);

		/*
		 * Note that the result will be either newf, or a stack of JoinExprs
		 * with newf at the base.  We rely on subsequent optimization steps to
		 * flatten this and rearrange the joins as needed.
		 *
		 * Although we could include the pulled-up subqueries in the returned
		 * relids, there's no need since upper quals couldn't refer to their
		 * outputs anyway.
		 */
		*relids = frelids;
		jtnode = jtlink;
	}
	else if (IsA(jtnode, JoinExpr))
	{
		JoinExpr   *j;
		Relids		leftrelids;
		Relids		rightrelids;
		Node	   *jtlink;

		/*
		 * Make a modifiable copy of join node, but don't bother copying its
		 * subnodes (yet).
		 */
		j = (JoinExpr *) palloc(sizeof(JoinExpr));
		memcpy(j, jtnode, sizeof(JoinExpr));
		jtlink = (Node *) j;

		/* Recurse to process children and collect their relids */
		j->larg = pull_up_sublinks_jointree_recurse(root, j->larg,
													&leftrelids);
		j->rarg = pull_up_sublinks_jointree_recurse(root, j->rarg,
													&rightrelids);

		/*
		 * Now process qual, showing appropriate child relids as available,
		 * and attach any pulled-up jointree items at the right place. In the
		 * inner-join case we put new JoinExprs above the existing one (much
		 * as for a FromExpr-style join).  In outer-join cases the new
		 * JoinExprs must go into the nullable side of the outer join. The
		 * point of the available_rels machinations is to ensure that we only
		 * pull up quals for which that's okay.
		 *
		 * We don't expect to see any pre-existing JOIN_SEMI or JOIN_ANTI
		 * nodes here.
		 */
		switch (j->jointype)
		{
			case JOIN_INNER:
				j->quals = pull_up_sublinks_qual_recurse(root, j->quals,
														 &jtlink,
														 bms_union(leftrelids,
																rightrelids),
														 NULL, NULL);
				break;
			case JOIN_LEFT:
				j->quals = pull_up_sublinks_qual_recurse(root, j->quals,
														 &j->rarg,
														 rightrelids,
														 NULL, NULL);
				break;
			case JOIN_FULL:
				/* can't do anything with full-join quals */
				break;
			case JOIN_RIGHT:
				j->quals = pull_up_sublinks_qual_recurse(root, j->quals,
														 &j->larg,
														 leftrelids,
														 NULL, NULL);
				break;
			default:
				elog(ERROR, "unrecognized join type: %d",
					 (int) j->jointype);
				break;
		}

		/*
		 * Although we could include the pulled-up subqueries in the returned
		 * relids, there's no need since upper quals couldn't refer to their
		 * outputs anyway.	But we *do* need to include the join's own rtindex
		 * because we haven't yet collapsed join alias variables, so upper
		 * levels would mistakenly think they couldn't use references to this
		 * join.
		 */
		*relids = bms_join(leftrelids, rightrelids);
		if (j->rtindex)
			*relids = bms_add_member(*relids, j->rtindex);
		jtnode = jtlink;
	}
	else
		elog(ERROR, "unrecognized node type: %d",
			 (int) nodeTag(jtnode));
	return jtnode;
}

/*
 * Recurse through top-level qual nodes for pull_up_sublinks()
 *
 * jtlink1 points to the link in the jointree where any new JoinExprs should
 * be inserted if they reference available_rels1 (i.e., available_rels1
 * denotes the relations present underneath jtlink1).  Optionally, jtlink2 can
 * point to a second link where new JoinExprs should be inserted if they
 * reference available_rels2 (pass NULL for both those arguments if not used).
 * Note that SubLinks referencing both sets of variables cannot be optimized.
 * If we find multiple pull-up-able SubLinks, they'll get stacked onto jtlink1
 * and/or jtlink2 in the order we encounter them.  We rely on subsequent
 * optimization to rearrange the stack if appropriate.
 *
 * Returns the replacement qual node, or NULL if the qual should be removed.
 */
static Node *
pull_up_sublinks_qual_recurse(PlannerInfo *root, Node *node,
							  Node **jtlink1, Relids available_rels1,
							  Node **jtlink2, Relids available_rels2)
{
	if (node == NULL)
		return NULL;
	if (IsA(node, SubLink))
	{
		SubLink    *sublink = (SubLink *) node;
		JoinExpr   *j;
		Relids		child_rels;

		/* Is it a convertible ANY or EXISTS clause? */
		if (sublink->subLinkType == ANY_SUBLINK)
		{
			if ((j = convert_ANY_sublink_to_join(root, sublink,
												 available_rels1)) != NULL)
			{
				/* Yes; insert the new join node into the join tree */
				j->larg = *jtlink1;
				*jtlink1 = (Node *) j;
				/* Recursively process pulled-up jointree nodes */
				j->rarg = pull_up_sublinks_jointree_recurse(root,
															j->rarg,
															&child_rels);

				/*
				 * Now recursively process the pulled-up quals.  Any inserted
				 * joins can get stacked onto either j->larg or j->rarg,
				 * depending on which rels they reference.
				 */
				j->quals = pull_up_sublinks_qual_recurse(root,
														 j->quals,
														 &j->larg,
														 available_rels1,
														 &j->rarg,
														 child_rels);
				/* Return NULL representing constant TRUE */
				return NULL;
			}
			if (available_rels2 != NULL &&
				(j = convert_ANY_sublink_to_join(root, sublink,
												 available_rels2)) != NULL)
			{
				/* Yes; insert the new join node into the join tree */
				j->larg = *jtlink2;
				*jtlink2 = (Node *) j;
				/* Recursively process pulled-up jointree nodes */
				j->rarg = pull_up_sublinks_jointree_recurse(root,
															j->rarg,
															&child_rels);

				/*
				 * Now recursively process the pulled-up quals.  Any inserted
				 * joins can get stacked onto either j->larg or j->rarg,
				 * depending on which rels they reference.
				 */
				j->quals = pull_up_sublinks_qual_recurse(root,
														 j->quals,
														 &j->larg,
														 available_rels2,
														 &j->rarg,
														 child_rels);
				/* Return NULL representing constant TRUE */
				return NULL;
			}
		}
		else if (sublink->subLinkType == EXISTS_SUBLINK)
		{
			if ((j = convert_EXISTS_sublink_to_join(root, sublink, false,
													available_rels1)) != NULL)
			{
				/* Yes; insert the new join node into the join tree */
				j->larg = *jtlink1;
				*jtlink1 = (Node *) j;
				/* Recursively process pulled-up jointree nodes */
				j->rarg = pull_up_sublinks_jointree_recurse(root,
															j->rarg,
															&child_rels);

				/*
				 * Now recursively process the pulled-up quals.  Any inserted
				 * joins can get stacked onto either j->larg or j->rarg,
				 * depending on which rels they reference.
				 */
				j->quals = pull_up_sublinks_qual_recurse(root,
														 j->quals,
														 &j->larg,
														 available_rels1,
														 &j->rarg,
														 child_rels);
				/* Return NULL representing constant TRUE */
				return NULL;
			}
			if (available_rels2 != NULL &&
				(j = convert_EXISTS_sublink_to_join(root, sublink, false,
													available_rels2)) != NULL)
			{
				/* Yes; insert the new join node into the join tree */
				j->larg = *jtlink2;
				*jtlink2 = (Node *) j;
				/* Recursively process pulled-up jointree nodes */
				j->rarg = pull_up_sublinks_jointree_recurse(root,
															j->rarg,
															&child_rels);

				/*
				 * Now recursively process the pulled-up quals.  Any inserted
				 * joins can get stacked onto either j->larg or j->rarg,
				 * depending on which rels they reference.
				 */
				j->quals = pull_up_sublinks_qual_recurse(root,
														 j->quals,
														 &j->larg,
														 available_rels2,
														 &j->rarg,
														 child_rels);
				/* Return NULL representing constant TRUE */
				return NULL;
			}
		}
		/* Else return it unmodified */
		return node;
	}
	if (not_clause(node))
	{
		/* If the immediate argument of NOT is EXISTS, try to convert */
		SubLink    *sublink = (SubLink *) get_notclausearg((Expr *) node);
		JoinExpr   *j;
		Relids		child_rels;

		if (sublink && IsA(sublink, SubLink))
		{
			if (sublink->subLinkType == EXISTS_SUBLINK)
			{
				if ((j = convert_EXISTS_sublink_to_join(root, sublink, true,
												   available_rels1)) != NULL)
				{
					/* Yes; insert the new join node into the join tree */
					j->larg = *jtlink1;
					*jtlink1 = (Node *) j;
					/* Recursively process pulled-up jointree nodes */
					j->rarg = pull_up_sublinks_jointree_recurse(root,
																j->rarg,
																&child_rels);

					/*
					 * Now recursively process the pulled-up quals.  Because
					 * we are underneath a NOT, we can't pull up sublinks that
					 * reference the left-hand stuff, but it's still okay to
					 * pull up sublinks referencing j->rarg.
					 */
					j->quals = pull_up_sublinks_qual_recurse(root,
															 j->quals,
															 &j->rarg,
															 child_rels,
															 NULL, NULL);
					/* Return NULL representing constant TRUE */
					return NULL;
				}
				if (available_rels2 != NULL &&
					(j = convert_EXISTS_sublink_to_join(root, sublink, true,
												   available_rels2)) != NULL)
				{
					/* Yes; insert the new join node into the join tree */
					j->larg = *jtlink2;
					*jtlink2 = (Node *) j;
					/* Recursively process pulled-up jointree nodes */
					j->rarg = pull_up_sublinks_jointree_recurse(root,
																j->rarg,
																&child_rels);

					/*
					 * Now recursively process the pulled-up quals.  Because
					 * we are underneath a NOT, we can't pull up sublinks that
					 * reference the left-hand stuff, but it's still okay to
					 * pull up sublinks referencing j->rarg.
					 */
					j->quals = pull_up_sublinks_qual_recurse(root,
															 j->quals,
															 &j->rarg,
															 child_rels,
															 NULL, NULL);
					/* Return NULL representing constant TRUE */
					return NULL;
				}
			}
		}
		/* Else return it unmodified */
		return node;
	}
	if (and_clause(node))
	{
		/* Recurse into AND clause */
		List	   *newclauses = NIL;
		ListCell   *l;

		foreach(l, ((BoolExpr *) node)->args)
		{
			Node	   *oldclause = (Node *) lfirst(l);
			Node	   *newclause;

			newclause = pull_up_sublinks_qual_recurse(root,
													  oldclause,
													  jtlink1,
													  available_rels1,
													  jtlink2,
													  available_rels2);
			if (newclause)
				newclauses = lappend(newclauses, newclause);
		}
		/* We might have got back fewer clauses than we started with */
		if (newclauses == NIL)
			return NULL;
		else if (list_length(newclauses) == 1)
			return (Node *) linitial(newclauses);
		else
			return (Node *) make_andclause(newclauses);
	}
	/* Stop if not an AND */
	return node;
}

/*
 * inline_set_returning_functions
 *		Attempt to "inline" set-returning functions in the FROM clause.
 *
 * If an RTE_FUNCTION rtable entry invokes a set-returning function that
 * contains just a simple SELECT, we can convert the rtable entry to an
 * RTE_SUBQUERY entry exposing the SELECT directly.  This is especially
 * useful if the subquery can then be "pulled up" for further optimization,
 * but we do it even if not, to reduce executor overhead.
 *
 * This has to be done before we have started to do any optimization of
 * subqueries, else any such steps wouldn't get applied to subqueries
 * obtained via inlining.  However, we do it after pull_up_sublinks
 * so that we can inline any functions used in SubLink subselects.
 *
 * Like most of the planner, this feels free to scribble on its input data
 * structure.
 */
void
inline_set_returning_functions(PlannerInfo *root)
{
	ListCell   *rt;

	foreach(rt, root->parse->rtable)
	{
		RangeTblEntry *rte = (RangeTblEntry *) lfirst(rt);

		if (rte->rtekind == RTE_FUNCTION)
		{
			Query	   *funcquery;

			/* Check safety of expansion, and expand if possible */
			funcquery = inline_set_returning_function(root, rte);
			if (funcquery)
			{
				/* Successful expansion, replace the rtable entry */
				rte->rtekind = RTE_SUBQUERY;
				rte->subquery = funcquery;
				rte->funcexpr = NULL;
				rte->funccoltypes = NIL;
				rte->funccoltypmods = NIL;
				rte->funccolcollations = NIL;
			}
		}
	}
}

/*
 * pull_up_subqueries
 *		Look for subqueries in the rangetable that can be pulled up into
 *		the parent query.  If the subquery has no special features like
 *		grouping/aggregation then we can merge it into the parent's jointree.
 *		Also, subqueries that are simple UNION ALL structures can be
 *		converted into "append relations".
 *
 * This recursively processes the jointree and returns a modified jointree.
 */
Node *
pull_up_subqueries(PlannerInfo *root, Node *jtnode)
{
	/* Start off with no containing join nor appendrel */
	return pull_up_subqueries_recurse(root, jtnode, NULL, NULL, NULL);
}

/*
 * pull_up_subqueries_recurse
 *		Recursive guts of pull_up_subqueries.
 *
 * If this jointree node is within either side of an outer join, then
 * lowest_outer_join references the lowest such JoinExpr node; otherwise
 * it is NULL.  We use this to constrain the effects of LATERAL subqueries.
 *
 * If this jointree node is within the nullable side of an outer join, then
 * lowest_nulling_outer_join references the lowest such JoinExpr node;
 * otherwise it is NULL.  This forces use of the PlaceHolderVar mechanism for
 * references to non-nullable targetlist items, but only for references above
 * that join.
 *
 * If we are looking at a member subquery of an append relation,
 * containing_appendrel describes that relation; else it is NULL.
 * This forces use of the PlaceHolderVar mechanism for all non-Var targetlist
 * items, and puts some additional restrictions on what can be pulled up.
 *
 * A tricky aspect of this code is that if we pull up a subquery we have
 * to replace Vars that reference the subquery's outputs throughout the
 * parent query, including quals attached to jointree nodes above the one
 * we are currently processing!  We handle this by being careful not to
 * change the jointree structure while recursing: no nodes other than
 * subquery RangeTblRef entries will be replaced.  Also, we can't turn
 * pullup_replace_vars loose on the whole jointree, because it'll return a
 * mutated copy of the tree; we have to invoke it just on the quals, instead.
 * This behavior is what makes it reasonable to pass lowest_outer_join and
 * lowest_nulling_outer_join as pointers rather than some more-indirect way
 * of identifying the lowest OJs.  Likewise, we don't replace append_rel_list
 * members but only their substructure, so the containing_appendrel reference
 * is safe to use.
 */
static Node *
pull_up_subqueries_recurse(PlannerInfo *root, Node *jtnode,
						   JoinExpr *lowest_outer_join,
						   JoinExpr *lowest_nulling_outer_join,
						   AppendRelInfo *containing_appendrel)
{
	if (jtnode == NULL)
		return NULL;
	if (IsA(jtnode, RangeTblRef))
	{
		int			varno = ((RangeTblRef *) jtnode)->rtindex;
		RangeTblEntry *rte = rt_fetch(varno, root->parse->rtable);

		/*
		 * Is this a subquery RTE, and if so, is the subquery simple enough to
		 * pull up?
		 *
		 * If we are looking at an append-relation member, we can't pull it up
		 * unless is_safe_append_member says so.
		 */
		if (rte->rtekind == RTE_SUBQUERY &&
			is_simple_subquery(rte->subquery, rte, lowest_outer_join) &&
			(containing_appendrel == NULL ||
			 is_safe_append_member(rte->subquery)))
			return pull_up_simple_subquery(root, jtnode, rte,
										   lowest_outer_join,
										   lowest_nulling_outer_join,
										   containing_appendrel);

		/*
		 * Alternatively, is it a simple UNION ALL subquery?  If so, flatten
		 * into an "append relation".
		 *
		 * It's safe to do this regardless of whether this query is itself an
		 * appendrel member.  (If you're thinking we should try to flatten the
		 * two levels of appendrel together, you're right; but we handle that
		 * in set_append_rel_pathlist, not here.)
		 */
		if (rte->rtekind == RTE_SUBQUERY &&
			is_simple_union_all(rte->subquery))
			return pull_up_simple_union_all(root, jtnode, rte);

		/* Otherwise, do nothing at this node. */
	}
	else if (IsA(jtnode, FromExpr))
	{
		FromExpr   *f = (FromExpr *) jtnode;
		ListCell   *l;

		Assert(containing_appendrel == NULL);
		foreach(l, f->fromlist)
			lfirst(l) = pull_up_subqueries_recurse(root, lfirst(l),
												   lowest_outer_join,
												   lowest_nulling_outer_join,
												   NULL);
	}
	else if (IsA(jtnode, JoinExpr))
	{
		JoinExpr   *j = (JoinExpr *) jtnode;

		Assert(containing_appendrel == NULL);
		/* Recurse, being careful to tell myself when inside outer join */
		switch (j->jointype)
		{
			case JOIN_INNER:
				j->larg = pull_up_subqueries_recurse(root, j->larg,
													 lowest_outer_join,
													 lowest_nulling_outer_join,
													 NULL);
				j->rarg = pull_up_subqueries_recurse(root, j->rarg,
													 lowest_outer_join,
													 lowest_nulling_outer_join,
													 NULL);
				break;
			case JOIN_LEFT:
			case JOIN_SEMI:
			case JOIN_ANTI:
				j->larg = pull_up_subqueries_recurse(root, j->larg,
													 j,
													 lowest_nulling_outer_join,
													 NULL);
				j->rarg = pull_up_subqueries_recurse(root, j->rarg,
													 j,
													 j,
													 NULL);
				break;
			case JOIN_FULL:
				j->larg = pull_up_subqueries_recurse(root, j->larg,
													 j,
													 j,
													 NULL);
				j->rarg = pull_up_subqueries_recurse(root, j->rarg,
													 j,
													 j,
													 NULL);
				break;
			case JOIN_RIGHT:
				j->larg = pull_up_subqueries_recurse(root, j->larg,
													 j,
													 j,
													 NULL);
				j->rarg = pull_up_subqueries_recurse(root, j->rarg,
													 j,
													 lowest_nulling_outer_join,
													 NULL);
				break;
			default:
				elog(ERROR, "unrecognized join type: %d",
					 (int) j->jointype);
				break;
		}
	}
	else
		elog(ERROR, "unrecognized node type: %d",
			 (int) nodeTag(jtnode));
	return jtnode;
}

/*
 * pull_up_simple_subquery
 *		Attempt to pull up a single simple subquery.
 *
 * jtnode is a RangeTblRef that has been tentatively identified as a simple
 * subquery by pull_up_subqueries.	We return the replacement jointree node,
 * or jtnode itself if we determine that the subquery can't be pulled up after
 * all.
 *
 * rte is the RangeTblEntry referenced by jtnode.  Remaining parameters are
 * as for pull_up_subqueries_recurse.
 */
static Node *
pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte,
						JoinExpr *lowest_outer_join,
						JoinExpr *lowest_nulling_outer_join,
						AppendRelInfo *containing_appendrel)
{
	Query	   *parse = root->parse;
	int			varno = ((RangeTblRef *) jtnode)->rtindex;
	Query	   *subquery;
	PlannerInfo *subroot;
	int			rtoffset;
	pullup_replace_vars_context rvcontext;
	ListCell   *lc;

	/*
	 * Need a modifiable copy of the subquery to hack on.  Even if we didn't
	 * sometimes choose not to pull up below, we must do this to avoid
	 * problems if the same subquery is referenced from multiple jointree
	 * items (which can't happen normally, but might after rule rewriting).
	 */
	subquery = copyObject(rte->subquery);

	/*
	 * Create a PlannerInfo data structure for this subquery.
	 *
	 * NOTE: the next few steps should match the first processing in
	 * subquery_planner().	Can we refactor to avoid code duplication, or
	 * would that just make things uglier?
	 */
	subroot = makeNode(PlannerInfo);
	subroot->parse = subquery;
	subroot->glob = root->glob;
	subroot->query_level = root->query_level;
	subroot->parent_root = root->parent_root;
	subroot->planner_cxt = CurrentMemoryContext;
	subroot->init_plans = NIL;
	subroot->cte_plan_ids = NIL;
	subroot->eq_classes = NIL;
	subroot->append_rel_list = NIL;
	subroot->rowMarks = NIL;
	subroot->hasRecursion = false;
	subroot->wt_param_id = -1;
	subroot->non_recursive_plan = NULL;

	/* No CTEs to worry about */
	Assert(subquery->cteList == NIL);

	/*
	 * Pull up any SubLinks within the subquery's quals, so that we don't
	 * leave unoptimized SubLinks behind.
	 */
	if (subquery->hasSubLinks)
		pull_up_sublinks(subroot);

	/*
	 * Similarly, inline any set-returning functions in its rangetable.
	 */
	inline_set_returning_functions(subroot);

	/*
	 * Recursively pull up the subquery's subqueries, so that
	 * pull_up_subqueries' processing is complete for its jointree and
	 * rangetable.
	 *
	 * Note: we should pass NULL for containing-join info even if we are
	 * within an outer join in the upper query; the lower query starts with a
	 * clean slate for outer-join semantics.  Likewise, we say we aren't
	 * handling an appendrel member.
	 */
	subquery->jointree = (FromExpr *)
		pull_up_subqueries_recurse(subroot, (Node *) subquery->jointree,
								   NULL, NULL, NULL);

	/*
	 * Now we must recheck whether the subquery is still simple enough to pull
	 * up.	If not, abandon processing it.
	 *
	 * We don't really need to recheck all the conditions involved, but it's
	 * easier just to keep this "if" looking the same as the one in
	 * pull_up_subqueries_recurse.
	 */
	if (is_simple_subquery(subquery, rte, lowest_outer_join) &&
		(containing_appendrel == NULL || is_safe_append_member(subquery)))
	{
		/* good to go */
	}
	else
	{
		/*
		 * Give up, return unmodified RangeTblRef.
		 *
		 * Note: The work we just did will be redone when the subquery gets
		 * planned on its own.	Perhaps we could avoid that by storing the
		 * modified subquery back into the rangetable, but I'm not gonna risk
		 * it now.
		 */
		return jtnode;
	}

	/*
	 * Adjust level-0 varnos in subquery so that we can append its rangetable
	 * to upper query's.  We have to fix the subquery's append_rel_list as
	 * well.
	 */
	rtoffset = list_length(parse->rtable);
	OffsetVarNodes((Node *) subquery, rtoffset, 0);
	OffsetVarNodes((Node *) subroot->append_rel_list, rtoffset, 0);

	/*
	 * Upper-level vars in subquery are now one level closer to their parent
	 * than before.
	 */
	IncrementVarSublevelsUp((Node *) subquery, -1, 1);
	IncrementVarSublevelsUp((Node *) subroot->append_rel_list, -1, 1);

	/*
	 * The subquery's targetlist items are now in the appropriate form to
	 * insert into the top query, but if we are under an outer join then
	 * non-nullable items may have to be turned into PlaceHolderVars.  If we
	 * are dealing with an appendrel member then anything that's not a simple
	 * Var has to be turned into a PlaceHolderVar.	Set up appropriate context
	 * data for pullup_replace_vars.
	 */
	rvcontext.root = root;
	rvcontext.targetlist = subquery->targetList;
	rvcontext.target_rte = rte;
	rvcontext.outer_hasSubLinks = &parse->hasSubLinks;
	rvcontext.varno = varno;
	rvcontext.need_phvs = (lowest_nulling_outer_join != NULL ||
						   containing_appendrel != NULL);
	rvcontext.wrap_non_vars = (containing_appendrel != NULL);
	/* initialize cache array with indexes 0 .. length(tlist) */
	rvcontext.rv_cache = palloc0((list_length(subquery->targetList) + 1) *
								 sizeof(Node *));

	/*
	 * Replace all of the top query's references to the subquery's outputs
	 * with copies of the adjusted subtlist items, being careful not to
	 * replace any of the jointree structure. (This'd be a lot cleaner if we
	 * could use query_tree_mutator.)  We have to use PHVs in the targetList,
	 * returningList, and havingQual, since those are certainly above any
	 * outer join.	replace_vars_in_jointree tracks its location in the
	 * jointree and uses PHVs or not appropriately.
	 */
	parse->targetList = (List *)
		pullup_replace_vars((Node *) parse->targetList, &rvcontext);
	parse->returningList = (List *)
		pullup_replace_vars((Node *) parse->returningList, &rvcontext);
	replace_vars_in_jointree((Node *) parse->jointree, &rvcontext,
							 lowest_nulling_outer_join);
	Assert(parse->setOperations == NULL);
	parse->havingQual = pullup_replace_vars(parse->havingQual, &rvcontext);

	/*
	 * Replace references in the translated_vars lists of appendrels. When
	 * pulling up an appendrel member, we do not need PHVs in the list of the
	 * parent appendrel --- there isn't any outer join between. Elsewhere, use
	 * PHVs for safety.  (This analysis could be made tighter but it seems
	 * unlikely to be worth much trouble.)
	 */
	foreach(lc, root->append_rel_list)
	{
		AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(lc);
		bool		save_need_phvs = rvcontext.need_phvs;

		if (appinfo == containing_appendrel)
			rvcontext.need_phvs = false;
		appinfo->translated_vars = (List *)
			pullup_replace_vars((Node *) appinfo->translated_vars, &rvcontext);
		rvcontext.need_phvs = save_need_phvs;
	}

	/*
	 * Replace references in the joinaliasvars lists of join RTEs.
	 *
	 * You might think that we could avoid using PHVs for alias vars of joins
	 * below lowest_nulling_outer_join, but that doesn't work because the
	 * alias vars could be referenced above that join; we need the PHVs to be
	 * present in such references after the alias vars get flattened.  (It
	 * might be worth trying to be smarter here, someday.)
	 */
	foreach(lc, parse->rtable)
	{
		RangeTblEntry *otherrte = (RangeTblEntry *) lfirst(lc);

		if (otherrte->rtekind == RTE_JOIN)
			otherrte->joinaliasvars = (List *)
				pullup_replace_vars((Node *) otherrte->joinaliasvars,
									&rvcontext);
	}

	/*
	 * If the subquery had a LATERAL marker, propagate that to any of its
	 * child RTEs that could possibly now contain lateral cross-references.
	 * The children might or might not contain any actual lateral
	 * cross-references, but we have to mark the pulled-up child RTEs so that
	 * later planner stages will check for such.
	 *
	 * NB: although the parser only sets the lateral flag in subquery and
	 * function RTEs, after this step it can also be set in VALUES RTEs.
	 */
	if (rte->lateral)
	{
		foreach(lc, subquery->rtable)
		{
			RangeTblEntry *child_rte = (RangeTblEntry *) lfirst(lc);

			switch (child_rte->rtekind)
			{
				case RTE_SUBQUERY:
				case RTE_FUNCTION:
				case RTE_VALUES:
					child_rte->lateral = true;
					break;
				case RTE_RELATION:
				case RTE_JOIN:
				case RTE_CTE:
					/* these can't contain any lateral references */
					break;
			}
		}
	}

	/*
	 * Now append the adjusted rtable entries to upper query. (We hold off
	 * until after fixing the upper rtable entries; no point in running that
	 * code on the subquery ones too.)
	 */
	parse->rtable = list_concat(parse->rtable, subquery->rtable);

	/*
	 * Pull up any FOR UPDATE/SHARE markers, too.  (OffsetVarNodes already
	 * adjusted the marker rtindexes, so just concat the lists.)
	 */
	parse->rowMarks = list_concat(parse->rowMarks, subquery->rowMarks);

	/*
	 * We also have to fix the relid sets of any PlaceHolderVar nodes in the
	 * parent query.  (This could perhaps be done by pullup_replace_vars(),
	 * but it seems cleaner to use two passes.)  Note in particular that any
	 * PlaceHolderVar nodes just created by pullup_replace_vars() will be
	 * adjusted, so having created them with the subquery's varno is correct.
	 *
	 * Likewise, relids appearing in AppendRelInfo nodes have to be fixed. We
	 * already checked that this won't require introducing multiple subrelids
	 * into the single-slot AppendRelInfo structs.
	 */
	if (parse->hasSubLinks || root->glob->lastPHId != 0 ||
		root->append_rel_list)
	{
		Relids		subrelids;

		subrelids = get_relids_in_jointree((Node *) subquery->jointree, false);
		substitute_multiple_relids((Node *) parse, varno, subrelids);
		fix_append_rel_relids(root->append_rel_list, varno, subrelids);
	}

	/*
	 * And now add subquery's AppendRelInfos to our list.
	 */
	root->append_rel_list = list_concat(root->append_rel_list,
										subroot->append_rel_list);

	/*
	 * We don't have to do the equivalent bookkeeping for outer-join info,
	 * because that hasn't been set up yet.  placeholder_list likewise.
	 */
	Assert(root->join_info_list == NIL);
	Assert(subroot->join_info_list == NIL);
	Assert(root->placeholder_list == NIL);
	Assert(subroot->placeholder_list == NIL);

	/*
	 * Miscellaneous housekeeping.
	 *
	 * Although replace_rte_variables() faithfully updated parse->hasSubLinks
	 * if it copied any SubLinks out of the subquery's targetlist, we still
	 * could have SubLinks added to the query in the expressions of FUNCTION
	 * and VALUES RTEs copied up from the subquery.  So it's necessary to copy
	 * subquery->hasSubLinks anyway.  Perhaps this can be improved someday.
	 */
	parse->hasSubLinks |= subquery->hasSubLinks;

	/*
	 * subquery won't be pulled up if it hasAggs or hasWindowFuncs, so no work
	 * needed on those flags
	 */

	/*
	 * Return the adjusted subquery jointree to replace the RangeTblRef entry
	 * in parent's jointree.
	 */
	return (Node *) subquery->jointree;
}

/*
 * pull_up_simple_union_all
 *		Pull up a single simple UNION ALL subquery.
 *
 * jtnode is a RangeTblRef that has been identified as a simple UNION ALL
 * subquery by pull_up_subqueries.	We pull up the leaf subqueries and
 * build an "append relation" for the union set.  The result value is just
 * jtnode, since we don't actually need to change the query jointree.
 */
static Node *
pull_up_simple_union_all(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte)
{
	int			varno = ((RangeTblRef *) jtnode)->rtindex;
	Query	   *subquery = rte->subquery;
	int			rtoffset = list_length(root->parse->rtable);
	List	   *rtable;

	/*
	 * Make a modifiable copy of the subquery's rtable, so we can adjust
	 * upper-level Vars in it.  There are no such Vars in the setOperations
	 * tree proper, so fixing the rtable should be sufficient.
	 */
	rtable = copyObject(subquery->rtable);

	/*
	 * Upper-level vars in subquery are now one level closer to their parent
	 * than before.  We don't have to worry about offsetting varnos, though,
	 * because the UNION leaf queries can't cross-reference each other.
	 */
	IncrementVarSublevelsUp_rtable(rtable, -1, 1);

	/*
	 * If the UNION ALL subquery had a LATERAL marker, propagate that to all
	 * its children.  The individual children might or might not contain any
	 * actual lateral cross-references, but we have to mark the pulled-up
	 * child RTEs so that later planner stages will check for such.
	 */
	if (rte->lateral)
	{
		ListCell   *rt;

		foreach(rt, rtable)
		{
			RangeTblEntry *child_rte = (RangeTblEntry *) lfirst(rt);

			Assert(child_rte->rtekind == RTE_SUBQUERY);
			child_rte->lateral = true;
		}
	}

	/*
	 * Append child RTEs to parent rtable.
	 */
	root->parse->rtable = list_concat(root->parse->rtable, rtable);

	/*
	 * Recursively scan the subquery's setOperations tree and add
	 * AppendRelInfo nodes for leaf subqueries to the parent's
	 * append_rel_list.  Also apply pull_up_subqueries to the leaf subqueries.
	 */
	Assert(subquery->setOperations);
	pull_up_union_leaf_queries(subquery->setOperations, root, varno, subquery,
							   rtoffset);

	/*
	 * Mark the parent as an append relation.
	 */
	rte->inh = true;

	return jtnode;
}

/*
 * pull_up_union_leaf_queries -- recursive guts of pull_up_simple_union_all
 *
 * Build an AppendRelInfo for each leaf query in the setop tree, and then
 * apply pull_up_subqueries to the leaf query.
 *
 * Note that setOpQuery is the Query containing the setOp node, whose tlist
 * contains references to all the setop output columns.  When called from
 * pull_up_simple_union_all, this is *not* the same as root->parse, which is
 * the parent Query we are pulling up into.
 *
 * parentRTindex is the appendrel parent's index in root->parse->rtable.
 *
 * The child RTEs have already been copied to the parent.  childRToffset
 * tells us where in the parent's range table they were copied.  When called
 * from flatten_simple_union_all, childRToffset is 0 since the child RTEs
 * were already in root->parse->rtable and no RT index adjustment is needed.
 */
static void
pull_up_union_leaf_queries(Node *setOp, PlannerInfo *root, int parentRTindex,
						   Query *setOpQuery, int childRToffset)
{
	if (IsA(setOp, RangeTblRef))
	{
		RangeTblRef *rtr = (RangeTblRef *) setOp;
		int			childRTindex;
		AppendRelInfo *appinfo;

		/*
		 * Calculate the index in the parent's range table
		 */
		childRTindex = childRToffset + rtr->rtindex;

		/*
		 * Build a suitable AppendRelInfo, and attach to parent's list.
		 */
		appinfo = makeNode(AppendRelInfo);
		appinfo->parent_relid = parentRTindex;
		appinfo->child_relid = childRTindex;
		appinfo->parent_reltype = InvalidOid;
		appinfo->child_reltype = InvalidOid;
		make_setop_translation_list(setOpQuery, childRTindex,
									&appinfo->translated_vars);
		appinfo->parent_reloid = InvalidOid;
		root->append_rel_list = lappend(root->append_rel_list, appinfo);

		/*
		 * Recursively apply pull_up_subqueries to the new child RTE.  (We
		 * must build the AppendRelInfo first, because this will modify it.)
		 * Note that we can pass NULL for containing-join info even if we're
		 * actually under an outer join, because the child's expressions
		 * aren't going to propagate up to the join.
		 */
		rtr = makeNode(RangeTblRef);
		rtr->rtindex = childRTindex;
		(void) pull_up_subqueries_recurse(root, (Node *) rtr,
										  NULL, NULL, appinfo);
	}
	else if (IsA(setOp, SetOperationStmt))
	{
		SetOperationStmt *op = (SetOperationStmt *) setOp;

		/* Recurse to reach leaf queries */
		pull_up_union_leaf_queries(op->larg, root, parentRTindex, setOpQuery,
								   childRToffset);
		pull_up_union_leaf_queries(op->rarg, root, parentRTindex, setOpQuery,
								   childRToffset);
	}
	else
	{
		elog(ERROR, "unrecognized node type: %d",
			 (int) nodeTag(setOp));
	}
}

/*
 * make_setop_translation_list
 *	  Build the list of translations from parent Vars to child Vars for
 *	  a UNION ALL member.  (At this point it's just a simple list of
 *	  referencing Vars, but if we succeed in pulling up the member
 *	  subquery, the Vars will get replaced by pulled-up expressions.)
 */
static void
make_setop_translation_list(Query *query, Index newvarno,
							List **translated_vars)
{
	List	   *vars = NIL;
	ListCell   *l;

	foreach(l, query->targetList)
	{
		TargetEntry *tle = (TargetEntry *) lfirst(l);

		if (tle->resjunk)
			continue;

		vars = lappend(vars, makeVarFromTargetEntry(newvarno, tle));
	}

	*translated_vars = vars;
}

/*
 * is_simple_subquery
 *	  Check a subquery in the range table to see if it's simple enough
 *	  to pull up into the parent query.
 *
 * rte is the RTE_SUBQUERY RangeTblEntry that contained the subquery.
 * (Note subquery is not necessarily equal to rte->subquery; it could be a
 * processed copy of that.)
 * lowest_outer_join is the lowest outer join above the subquery, or NULL.
 */
static bool
is_simple_subquery(Query *subquery, RangeTblEntry *rte,
				   JoinExpr *lowest_outer_join)
{
	/*
	 * Let's just make sure it's a valid subselect ...
	 */
	if (!IsA(subquery, Query) ||
		subquery->commandType != CMD_SELECT ||
		subquery->utilityStmt != NULL)
		elog(ERROR, "subquery is bogus");

	/*
	 * Can't currently pull up a query with setops (unless it's simple UNION
	 * ALL, which is handled by a different code path). Maybe after querytree
	 * redesign...
	 */
	if (subquery->setOperations)
		return false;

	/*
	 * Can't pull up a subquery involving grouping, aggregation, sorting,
	 * limiting, or WITH.  (XXX WITH could possibly be allowed later)
	 *
	 * We also don't pull up a subquery that has explicit FOR UPDATE/SHARE
	 * clauses, because pullup would cause the locking to occur semantically
	 * higher than it should.  Implicit FOR UPDATE/SHARE is okay because in
	 * that case the locking was originally declared in the upper query
	 * anyway.
	 */
	if (subquery->hasAggs ||
		subquery->hasWindowFuncs ||
		subquery->groupClause ||
		subquery->havingQual ||
		subquery->sortClause ||
		subquery->distinctClause ||
		subquery->limitOffset ||
		subquery->limitCount ||
		subquery->hasForUpdate ||
		subquery->cteList)
		return false;

	/*
	 * Don't pull up if the RTE represents a security-barrier view; we couldn't
	 * prevent information leakage once the RTE's Vars are scattered about in
	 * the upper query.
	 */
	if (rte->security_barrier)
		return false;

	/*
	 * If the subquery is LATERAL, and we're below any outer join, and the
	 * subquery contains lateral references to rels outside the outer join,
	 * don't pull up.  Doing so would risk creating outer-join quals that
	 * contain references to rels outside the outer join, which is a semantic
	 * mess that doesn't seem worth addressing at the moment.
	 */
	if (rte->lateral && lowest_outer_join != NULL)
	{
		Relids	lvarnos = pull_varnos_of_level((Node *) subquery, 1);
		Relids	jvarnos = get_relids_in_jointree((Node *) lowest_outer_join,
												 true);

		if (!bms_is_subset(lvarnos, jvarnos))
			return false;
	}

	/*
	 * Don't pull up a subquery that has any set-returning functions in its
	 * targetlist.	Otherwise we might well wind up inserting set-returning
	 * functions into places where they mustn't go, such as quals of higher
	 * queries.
	 */
	if (expression_returns_set((Node *) subquery->targetList))
		return false;

	/*
	 * Don't pull up a subquery that has any volatile functions in its
	 * targetlist.	Otherwise we might introduce multiple evaluations of these
	 * functions, if they get copied to multiple places in the upper query,
	 * leading to surprising results.  (Note: the PlaceHolderVar mechanism
	 * doesn't quite guarantee single evaluation; else we could pull up anyway
	 * and just wrap such items in PlaceHolderVars ...)
	 */
	if (contain_volatile_functions((Node *) subquery->targetList))
		return false;

	/*
	 * Hack: don't try to pull up a subquery with an empty jointree.
	 * query_planner() will correctly generate a Result plan for a jointree
	 * that's totally empty, but I don't think the right things happen if an
	 * empty FromExpr appears lower down in a jointree.  It would pose a
	 * problem for the PlaceHolderVar mechanism too, since we'd have no way to
	 * identify where to evaluate a PHV coming out of the subquery. Not worth
	 * working hard on this, just to collapse SubqueryScan/Result into Result;
	 * especially since the SubqueryScan can often be optimized away by
	 * setrefs.c anyway.
	 */
	if (subquery->jointree->fromlist == NIL)
		return false;

	return true;
}

/*
 * is_simple_union_all
 *	  Check a subquery to see if it's a simple UNION ALL.
 *
 * We require all the setops to be UNION ALL (no mixing) and there can't be
 * any datatype coercions involved, ie, all the leaf queries must emit the
 * same datatypes.
 */
static bool
is_simple_union_all(Query *subquery)
{
	SetOperationStmt *topop;

	/* Let's just make sure it's a valid subselect ... */
	if (!IsA(subquery, Query) ||
		subquery->commandType != CMD_SELECT ||
		subquery->utilityStmt != NULL)
		elog(ERROR, "subquery is bogus");

	/* Is it a set-operation query at all? */
	topop = (SetOperationStmt *) subquery->setOperations;
	if (!topop)
		return false;
	Assert(IsA(topop, SetOperationStmt));

	/* Can't handle ORDER BY, LIMIT/OFFSET, locking, or WITH */
	if (subquery->sortClause ||
		subquery->limitOffset ||
		subquery->limitCount ||
		subquery->rowMarks ||
		subquery->cteList)
		return false;

	/* Recursively check the tree of set operations */
	return is_simple_union_all_recurse((Node *) topop, subquery,
									   topop->colTypes);
}

static bool
is_simple_union_all_recurse(Node *setOp, Query *setOpQuery, List *colTypes)
{
	if (IsA(setOp, RangeTblRef))
	{
		RangeTblRef *rtr = (RangeTblRef *) setOp;
		RangeTblEntry *rte = rt_fetch(rtr->rtindex, setOpQuery->rtable);
		Query	   *subquery = rte->subquery;

		Assert(subquery != NULL);

		/* Leaf nodes are OK if they match the toplevel column types */
		/* We don't have to compare typmods or collations here */
		return tlist_same_datatypes(subquery->targetList, colTypes, true);
	}
	else if (IsA(setOp, SetOperationStmt))
	{
		SetOperationStmt *op = (SetOperationStmt *) setOp;

		/* Must be UNION ALL */
		if (op->op != SETOP_UNION || !op->all)
			return false;

		/* Recurse to check inputs */
		return is_simple_union_all_recurse(op->larg, setOpQuery, colTypes) &&
			is_simple_union_all_recurse(op->rarg, setOpQuery, colTypes);
	}
	else
	{
		elog(ERROR, "unrecognized node type: %d",
			 (int) nodeTag(setOp));
		return false;			/* keep compiler quiet */
	}
}

/*
 * is_safe_append_member
 *	  Check a subquery that is a leaf of a UNION ALL appendrel to see if it's
 *	  safe to pull up.
 */
static bool
is_safe_append_member(Query *subquery)
{
	FromExpr   *jtnode;

	/*
	 * It's only safe to pull up the child if its jointree contains exactly
	 * one RTE, else the AppendRelInfo data structure breaks. The one base RTE
	 * could be buried in several levels of FromExpr, however.
	 *
	 * Also, the child can't have any WHERE quals because there's no place to
	 * put them in an appendrel.  (This is a bit annoying...) If we didn't
	 * need to check this, we'd just test whether get_relids_in_jointree()
	 * yields a singleton set, to be more consistent with the coding of
	 * fix_append_rel_relids().
	 */
	jtnode = subquery->jointree;
	while (IsA(jtnode, FromExpr))
	{
		if (jtnode->quals != NULL)
			return false;
		if (list_length(jtnode->fromlist) != 1)
			return false;
		jtnode = linitial(jtnode->fromlist);
	}
	if (!IsA(jtnode, RangeTblRef))
		return false;

	return true;
}

/*
 * Helper routine for pull_up_subqueries: do pullup_replace_vars on every
 * expression in the jointree, without changing the jointree structure itself.
 * Ugly, but there's no other way...
 *
 * If we are at or below lowest_nulling_outer_join, we can suppress use of
 * PlaceHolderVars wrapped around the replacement expressions.
 */
static void
replace_vars_in_jointree(Node *jtnode,
						 pullup_replace_vars_context *context,
						 JoinExpr *lowest_nulling_outer_join)
{
	if (jtnode == NULL)
		return;
	if (IsA(jtnode, RangeTblRef))
	{
		/*
		 * If the RangeTblRef refers to a LATERAL subquery (that isn't the
		 * same subquery we're pulling up), it might contain references to the
		 * target subquery, which we must replace.  We drive this from the
		 * jointree scan, rather than a scan of the rtable, for a couple of
		 * reasons: we can avoid processing no-longer-referenced RTEs, and we
		 * can use the appropriate setting of need_phvs depending on whether
		 * the RTE is above possibly-nulling outer joins or not.
		 */
		int			varno = ((RangeTblRef *) jtnode)->rtindex;

		if (varno != context->varno)	/* ignore target subquery itself */
		{
			RangeTblEntry *rte = rt_fetch(varno, context->root->parse->rtable);

			Assert(rte != context->target_rte);
			if (rte->lateral)
			{
				switch (rte->rtekind)
				{
					case RTE_SUBQUERY:
						rte->subquery =
							pullup_replace_vars_subquery(rte->subquery,
														 context);
						break;
					case RTE_FUNCTION:
						rte->funcexpr =
							pullup_replace_vars(rte->funcexpr,
												context);
						break;
					case RTE_VALUES:
						rte->values_lists = (List *)
							pullup_replace_vars((Node *) rte->values_lists,
												context);
						break;
					case RTE_RELATION:
					case RTE_JOIN:
					case RTE_CTE:
						/* these shouldn't be marked LATERAL */
						Assert(false);
						break;
				}
			}
		}
	}
	else if (IsA(jtnode, FromExpr))
	{
		FromExpr   *f = (FromExpr *) jtnode;
		ListCell   *l;

		foreach(l, f->fromlist)
			replace_vars_in_jointree(lfirst(l), context,
									 lowest_nulling_outer_join);
		f->quals = pullup_replace_vars(f->quals, context);
	}
	else if (IsA(jtnode, JoinExpr))
	{
		JoinExpr   *j = (JoinExpr *) jtnode;
		bool		save_need_phvs = context->need_phvs;

		if (j == lowest_nulling_outer_join)
		{
			/* no more PHVs in or below this join */
			context->need_phvs = false;
			lowest_nulling_outer_join = NULL;
		}
		replace_vars_in_jointree(j->larg, context, lowest_nulling_outer_join);
		replace_vars_in_jointree(j->rarg, context, lowest_nulling_outer_join);
		j->quals = pullup_replace_vars(j->quals, context);

		/*
		 * We don't bother to update the colvars list, since it won't be used
		 * again ...
		 */
		context->need_phvs = save_need_phvs;
	}
	else
		elog(ERROR, "unrecognized node type: %d",
			 (int) nodeTag(jtnode));
}

/*
 * Apply pullup variable replacement throughout an expression tree
 *
 * Returns a modified copy of the tree, so this can't be used where we
 * need to do in-place replacement.
 */
static Node *
pullup_replace_vars(Node *expr, pullup_replace_vars_context *context)
{
	return replace_rte_variables(expr,
								 context->varno, 0,
								 pullup_replace_vars_callback,
								 (void *) context,
								 context->outer_hasSubLinks);
}

static Node *
pullup_replace_vars_callback(Var *var,
							 replace_rte_variables_context *context)
{
	pullup_replace_vars_context *rcon = (pullup_replace_vars_context *) context->callback_arg;
	int			varattno = var->varattno;
	Node	   *newnode;

	/*
	 * If PlaceHolderVars are needed, we cache the modified expressions in
	 * rcon->rv_cache[].  This is not in hopes of any material speed gain
	 * within this function, but to avoid generating identical PHVs with
	 * different IDs.  That would result in duplicate evaluations at runtime,
	 * and possibly prevent optimizations that rely on recognizing different
	 * references to the same subquery output as being equal().  So it's worth
	 * a bit of extra effort to avoid it.
	 */
	if (rcon->need_phvs &&
		varattno >= InvalidAttrNumber &&
		varattno <= list_length(rcon->targetlist) &&
		rcon->rv_cache[varattno] != NULL)
	{
		/* Just copy the entry and fall through to adjust its varlevelsup */
		newnode = copyObject(rcon->rv_cache[varattno]);
	}
	else if (varattno == InvalidAttrNumber)
	{
		/* Must expand whole-tuple reference into RowExpr */
		RowExpr    *rowexpr;
		List	   *colnames;
		List	   *fields;
		bool		save_need_phvs = rcon->need_phvs;
		int			save_sublevelsup = context->sublevels_up;

		/*
		 * If generating an expansion for a var of a named rowtype (ie, this
		 * is a plain relation RTE), then we must include dummy items for
		 * dropped columns.  If the var is RECORD (ie, this is a JOIN), then
		 * omit dropped columns. Either way, attach column names to the
		 * RowExpr for use of ruleutils.c.
		 *
		 * In order to be able to cache the results, we always generate the
		 * expansion with varlevelsup = 0, and then adjust if needed.
		 */
		expandRTE(rcon->target_rte,
				  var->varno, 0 /* not varlevelsup */ , var->location,
				  (var->vartype != RECORDOID),
				  &colnames, &fields);
		/* Adjust the generated per-field Vars, but don't insert PHVs */
		rcon->need_phvs = false;
		context->sublevels_up = 0;		/* to match the expandRTE output */
		fields = (List *) replace_rte_variables_mutator((Node *) fields,
														context);
		rcon->need_phvs = save_need_phvs;
		context->sublevels_up = save_sublevelsup;

		rowexpr = makeNode(RowExpr);
		rowexpr->args = fields;
		rowexpr->row_typeid = var->vartype;
		rowexpr->row_format = COERCE_IMPLICIT_CAST;
		rowexpr->colnames = colnames;
		rowexpr->location = var->location;
		newnode = (Node *) rowexpr;

		/*
		 * Insert PlaceHolderVar if needed.  Notice that we are wrapping one
		 * PlaceHolderVar around the whole RowExpr, rather than putting one
		 * around each element of the row.	This is because we need the
		 * expression to yield NULL, not ROW(NULL,NULL,...) when it is forced
		 * to null by an outer join.
		 */
		if (rcon->need_phvs)
		{
			/* RowExpr is certainly not strict, so always need PHV */
			newnode = (Node *)
				make_placeholder_expr(rcon->root,
									  (Expr *) newnode,
									  bms_make_singleton(rcon->varno));
			/* cache it with the PHV, and with varlevelsup still zero */
			rcon->rv_cache[InvalidAttrNumber] = copyObject(newnode);
		}
	}
	else
	{
		/* Normal case referencing one targetlist element */
		TargetEntry *tle = get_tle_by_resno(rcon->targetlist, varattno);

		if (tle == NULL)		/* shouldn't happen */
			elog(ERROR, "could not find attribute %d in subquery targetlist",
				 varattno);

		/* Make a copy of the tlist item to return */
		newnode = copyObject(tle->expr);

		/* Insert PlaceHolderVar if needed */
		if (rcon->need_phvs)
		{
			bool		wrap;

			if (newnode && IsA(newnode, Var) &&
				((Var *) newnode)->varlevelsup == 0)
			{
				/* Simple Vars always escape being wrapped */
				wrap = false;
			}
			else if (newnode && IsA(newnode, PlaceHolderVar) &&
					 ((PlaceHolderVar *) newnode)->phlevelsup == 0)
			{
				/* No need to wrap a PlaceHolderVar with another one, either */
				wrap = false;
			}
			else if (rcon->wrap_non_vars)
			{
				/* Wrap all non-Vars in a PlaceHolderVar */
				wrap = true;
			}
			else
			{
				/*
				 * If it contains a Var of current level, and does not contain
				 * any non-strict constructs, then it's certainly nullable so
				 * we don't need to insert a PlaceHolderVar.
				 *
				 * This analysis could be tighter: in particular, a non-strict
				 * construct hidden within a lower-level PlaceHolderVar is not
				 * reason to add another PHV.  But for now it doesn't seem
				 * worth the code to be more exact.
				 *
				 * Note: in future maybe we should insert a PlaceHolderVar
				 * anyway, if the tlist item is expensive to evaluate?
				 */
				if (contain_vars_of_level((Node *) newnode, 0) &&
					!contain_nonstrict_functions((Node *) newnode))
				{
					/* No wrap needed */
					wrap = false;
				}
				else
				{
					/* Else wrap it in a PlaceHolderVar */
					wrap = true;
				}
			}

			if (wrap)
				newnode = (Node *)
					make_placeholder_expr(rcon->root,
										  (Expr *) newnode,
										  bms_make_singleton(rcon->varno));

			/*
			 * Cache it if possible (ie, if the attno is in range, which it
			 * probably always should be).	We can cache the value even if we
			 * decided we didn't need a PHV, since this result will be
			 * suitable for any request that has need_phvs.
			 */
			if (varattno > InvalidAttrNumber &&
				varattno <= list_length(rcon->targetlist))
				rcon->rv_cache[varattno] = copyObject(newnode);
		}
	}

	/* Must adjust varlevelsup if tlist item is from higher query */
	if (var->varlevelsup > 0)
		IncrementVarSublevelsUp(newnode, var->varlevelsup, 0);

	return newnode;
}

/*
 * Apply pullup variable replacement to a subquery
 *
 * This needs to be different from pullup_replace_vars() because
 * replace_rte_variables will think that it shouldn't increment sublevels_up
 * before entering the Query; so we need to call it with sublevels_up == 1.
 */
static Query *
pullup_replace_vars_subquery(Query *query,
							 pullup_replace_vars_context *context)
{
	Assert(IsA(query, Query));
	return (Query *) replace_rte_variables((Node *) query,
										   context->varno, 1,
										   pullup_replace_vars_callback,
										   (void *) context,
										   NULL);
}


/*
 * flatten_simple_union_all
 *		Try to optimize top-level UNION ALL structure into an appendrel
 *
 * If a query's setOperations tree consists entirely of simple UNION ALL
 * operations, flatten it into an append relation, which we can process more
 * intelligently than the general setops case.	Otherwise, do nothing.
 *
 * In most cases, this can succeed only for a top-level query, because for a
 * subquery in FROM, the parent query's invocation of pull_up_subqueries would
 * already have flattened the UNION via pull_up_simple_union_all.  But there
 * are a few cases we can support here but not in that code path, for example
 * when the subquery also contains ORDER BY.
 */
void
flatten_simple_union_all(PlannerInfo *root)
{
	Query	   *parse = root->parse;
	SetOperationStmt *topop;
	Node	   *leftmostjtnode;
	int			leftmostRTI;
	RangeTblEntry *leftmostRTE;
	int			childRTI;
	RangeTblEntry *childRTE;
	RangeTblRef *rtr;

	/* Shouldn't be called unless query has setops */
	topop = (SetOperationStmt *) parse->setOperations;
	Assert(topop && IsA(topop, SetOperationStmt));

	/* Can't optimize away a recursive UNION */
	if (root->hasRecursion)
		return;

	/*
	 * Recursively check the tree of set operations.  If not all UNION ALL
	 * with identical column types, punt.
	 */
	if (!is_simple_union_all_recurse((Node *) topop, parse, topop->colTypes))
		return;

	/*
	 * Locate the leftmost leaf query in the setops tree.  The upper query's
	 * Vars all refer to this RTE (see transformSetOperationStmt).
	 */
	leftmostjtnode = topop->larg;
	while (leftmostjtnode && IsA(leftmostjtnode, SetOperationStmt))
		leftmostjtnode = ((SetOperationStmt *) leftmostjtnode)->larg;
	Assert(leftmostjtnode && IsA(leftmostjtnode, RangeTblRef));
	leftmostRTI = ((RangeTblRef *) leftmostjtnode)->rtindex;
	leftmostRTE = rt_fetch(leftmostRTI, parse->rtable);
	Assert(leftmostRTE->rtekind == RTE_SUBQUERY);

	/*
	 * Make a copy of the leftmost RTE and add it to the rtable.  This copy
	 * will represent the leftmost leaf query in its capacity as a member of
	 * the appendrel.  The original will represent the appendrel as a whole.
	 * (We must do things this way because the upper query's Vars have to be
	 * seen as referring to the whole appendrel.)
	 */
	childRTE = copyObject(leftmostRTE);
	parse->rtable = lappend(parse->rtable, childRTE);
	childRTI = list_length(parse->rtable);

	/* Modify the setops tree to reference the child copy */
	((RangeTblRef *) leftmostjtnode)->rtindex = childRTI;

	/* Modify the formerly-leftmost RTE to mark it as an appendrel parent */
	leftmostRTE->inh = true;

	/*
	 * Form a RangeTblRef for the appendrel, and insert it into FROM.  The top
	 * Query of a setops tree should have had an empty FromClause initially.
	 */
	rtr = makeNode(RangeTblRef);
	rtr->rtindex = leftmostRTI;
	Assert(parse->jointree->fromlist == NIL);
	parse->jointree->fromlist = list_make1(rtr);

	/*
	 * Now pretend the query has no setops.  We must do this before trying to
	 * do subquery pullup, because of Assert in pull_up_simple_subquery.
	 */
	parse->setOperations = NULL;

	/*
	 * Build AppendRelInfo information, and apply pull_up_subqueries to the
	 * leaf queries of the UNION ALL.  (We must do that now because they
	 * weren't previously referenced by the jointree, and so were missed by
	 * the main invocation of pull_up_subqueries.)
	 */
	pull_up_union_leaf_queries((Node *) topop, root, leftmostRTI, parse, 0);
}


/*
 * reduce_outer_joins
 *		Attempt to reduce outer joins to plain inner joins.
 *
 * The idea here is that given a query like
 *		SELECT ... FROM a LEFT JOIN b ON (...) WHERE b.y = 42;
 * we can reduce the LEFT JOIN to a plain JOIN if the "=" operator in WHERE
 * is strict.  The strict operator will always return NULL, causing the outer
 * WHERE to fail, on any row where the LEFT JOIN filled in NULLs for b's
 * columns.  Therefore, there's no need for the join to produce null-extended
 * rows in the first place --- which makes it a plain join not an outer join.
 * (This scenario may not be very likely in a query written out by hand, but
 * it's reasonably likely when pushing quals down into complex views.)
 *
 * More generally, an outer join can be reduced in strength if there is a
 * strict qual above it in the qual tree that constrains a Var from the
 * nullable side of the join to be non-null.  (For FULL joins this applies
 * to each side separately.)
 *
 * Another transformation we apply here is to recognize cases like
 *		SELECT ... FROM a LEFT JOIN b ON (a.x = b.y) WHERE b.y IS NULL;
 * If the join clause is strict for b.y, then only null-extended rows could
 * pass the upper WHERE, and we can conclude that what the query is really
 * specifying is an anti-semijoin.	We change the join type from JOIN_LEFT
 * to JOIN_ANTI.  The IS NULL clause then becomes redundant, and must be
 * removed to prevent bogus selectivity calculations, but we leave it to
 * distribute_qual_to_rels to get rid of such clauses.
 *
 * Also, we get rid of JOIN_RIGHT cases by flipping them around to become
 * JOIN_LEFT.  This saves some code here and in some later planner routines,
 * but the main reason to do it is to not need to invent a JOIN_REVERSE_ANTI
 * join type.
 *
 * To ease recognition of strict qual clauses, we require this routine to be
 * run after expression preprocessing (i.e., qual canonicalization and JOIN
 * alias-var expansion).
 */
void
reduce_outer_joins(PlannerInfo *root)
{
	reduce_outer_joins_state *state;

	/*
	 * To avoid doing strictness checks on more quals than necessary, we want
	 * to stop descending the jointree as soon as there are no outer joins
	 * below our current point.  This consideration forces a two-pass process.
	 * The first pass gathers information about which base rels appear below
	 * each side of each join clause, and about whether there are outer
	 * join(s) below each side of each join clause. The second pass examines
	 * qual clauses and changes join types as it descends the tree.
	 */
	state = reduce_outer_joins_pass1((Node *) root->parse->jointree);

	/* planner.c shouldn't have called me if no outer joins */
	if (state == NULL || !state->contains_outer)
		elog(ERROR, "so where are the outer joins?");

	reduce_outer_joins_pass2((Node *) root->parse->jointree,
							 state, root, NULL, NIL, NIL);
}

/*
 * reduce_outer_joins_pass1 - phase 1 data collection
 *
 * Returns a state node describing the given jointree node.
 */
static reduce_outer_joins_state *
reduce_outer_joins_pass1(Node *jtnode)
{
	reduce_outer_joins_state *result;

	result = (reduce_outer_joins_state *)
		palloc(sizeof(reduce_outer_joins_state));
	result->relids = NULL;
	result->contains_outer = false;
	result->sub_states = NIL;

	if (jtnode == NULL)
		return result;
	if (IsA(jtnode, RangeTblRef))
	{
		int			varno = ((RangeTblRef *) jtnode)->rtindex;

		result->relids = bms_make_singleton(varno);
	}
	else if (IsA(jtnode, FromExpr))
	{
		FromExpr   *f = (FromExpr *) jtnode;
		ListCell   *l;

		foreach(l, f->fromlist)
		{
			reduce_outer_joins_state *sub_state;

			sub_state = reduce_outer_joins_pass1(lfirst(l));
			result->relids = bms_add_members(result->relids,
											 sub_state->relids);
			result->contains_outer |= sub_state->contains_outer;
			result->sub_states = lappend(result->sub_states, sub_state);
		}
	}
	else if (IsA(jtnode, JoinExpr))
	{
		JoinExpr   *j = (JoinExpr *) jtnode;
		reduce_outer_joins_state *sub_state;

		/* join's own RT index is not wanted in result->relids */
		if (IS_OUTER_JOIN(j->jointype))
			result->contains_outer = true;

		sub_state = reduce_outer_joins_pass1(j->larg);
		result->relids = bms_add_members(result->relids,
										 sub_state->relids);
		result->contains_outer |= sub_state->contains_outer;
		result->sub_states = lappend(result->sub_states, sub_state);

		sub_state = reduce_outer_joins_pass1(j->rarg);
		result->relids = bms_add_members(result->relids,
										 sub_state->relids);
		result->contains_outer |= sub_state->contains_outer;
		result->sub_states = lappend(result->sub_states, sub_state);
	}
	else
		elog(ERROR, "unrecognized node type: %d",
			 (int) nodeTag(jtnode));
	return result;
}

/*
 * reduce_outer_joins_pass2 - phase 2 processing
 *
 *	jtnode: current jointree node
 *	state: state data collected by phase 1 for this node
 *	root: toplevel planner state
 *	nonnullable_rels: set of base relids forced non-null by upper quals
 *	nonnullable_vars: list of Vars forced non-null by upper quals
 *	forced_null_vars: list of Vars forced null by upper quals
 */
static void
reduce_outer_joins_pass2(Node *jtnode,
						 reduce_outer_joins_state *state,
						 PlannerInfo *root,
						 Relids nonnullable_rels,
						 List *nonnullable_vars,
						 List *forced_null_vars)
{
	/*
	 * pass 2 should never descend as far as an empty subnode or base rel,
	 * because it's only called on subtrees marked as contains_outer.
	 */
	if (jtnode == NULL)
		elog(ERROR, "reached empty jointree");
	if (IsA(jtnode, RangeTblRef))
		elog(ERROR, "reached base rel");
	else if (IsA(jtnode, FromExpr))
	{
		FromExpr   *f = (FromExpr *) jtnode;
		ListCell   *l;
		ListCell   *s;
		Relids		pass_nonnullable_rels;
		List	   *pass_nonnullable_vars;
		List	   *pass_forced_null_vars;

		/* Scan quals to see if we can add any constraints */
		pass_nonnullable_rels = find_nonnullable_rels(f->quals);
		pass_nonnullable_rels = bms_add_members(pass_nonnullable_rels,
												nonnullable_rels);
		/* NB: we rely on list_concat to not damage its second argument */
		pass_nonnullable_vars = find_nonnullable_vars(f->quals);
		pass_nonnullable_vars = list_concat(pass_nonnullable_vars,
											nonnullable_vars);
		pass_forced_null_vars = find_forced_null_vars(f->quals);
		pass_forced_null_vars = list_concat(pass_forced_null_vars,
											forced_null_vars);
		/* And recurse --- but only into interesting subtrees */
		Assert(list_length(f->fromlist) == list_length(state->sub_states));
		forboth(l, f->fromlist, s, state->sub_states)
		{
			reduce_outer_joins_state *sub_state = lfirst(s);

			if (sub_state->contains_outer)
				reduce_outer_joins_pass2(lfirst(l), sub_state, root,
										 pass_nonnullable_rels,
										 pass_nonnullable_vars,
										 pass_forced_null_vars);
		}
		bms_free(pass_nonnullable_rels);
		/* can't so easily clean up var lists, unfortunately */
	}
	else if (IsA(jtnode, JoinExpr))
	{
		JoinExpr   *j = (JoinExpr *) jtnode;
		int			rtindex = j->rtindex;
		JoinType	jointype = j->jointype;
		reduce_outer_joins_state *left_state = linitial(state->sub_states);
		reduce_outer_joins_state *right_state = lsecond(state->sub_states);
		List	   *local_nonnullable_vars = NIL;
		bool		computed_local_nonnullable_vars = false;

		/* Can we simplify this join? */
		switch (jointype)
		{
			case JOIN_INNER:
				break;
			case JOIN_LEFT:
				if (bms_overlap(nonnullable_rels, right_state->relids))
					jointype = JOIN_INNER;
				break;
			case JOIN_RIGHT:
				if (bms_overlap(nonnullable_rels, left_state->relids))
					jointype = JOIN_INNER;
				break;
			case JOIN_FULL:
				if (bms_overlap(nonnullable_rels, left_state->relids))
				{
					if (bms_overlap(nonnullable_rels, right_state->relids))
						jointype = JOIN_INNER;
					else
						jointype = JOIN_LEFT;
				}
				else
				{
					if (bms_overlap(nonnullable_rels, right_state->relids))
						jointype = JOIN_RIGHT;
				}
				break;
			case JOIN_SEMI:
			case JOIN_ANTI:

				/*
				 * These could only have been introduced by pull_up_sublinks,
				 * so there's no way that upper quals could refer to their
				 * righthand sides, and no point in checking.
				 */
				break;
			default:
				elog(ERROR, "unrecognized join type: %d",
					 (int) jointype);
				break;
		}

		/*
		 * Convert JOIN_RIGHT to JOIN_LEFT.  Note that in the case where we
		 * reduced JOIN_FULL to JOIN_RIGHT, this will mean the JoinExpr no
		 * longer matches the internal ordering of any CoalesceExpr's built to
		 * represent merged join variables.  We don't care about that at
		 * present, but be wary of it ...
		 */
		if (jointype == JOIN_RIGHT)
		{
			Node	   *tmparg;

			tmparg = j->larg;
			j->larg = j->rarg;
			j->rarg = tmparg;
			jointype = JOIN_LEFT;
			right_state = linitial(state->sub_states);
			left_state = lsecond(state->sub_states);
		}

		/*
		 * See if we can reduce JOIN_LEFT to JOIN_ANTI.  This is the case if
		 * the join's own quals are strict for any var that was forced null by
		 * higher qual levels.	NOTE: there are other ways that we could
		 * detect an anti-join, in particular if we were to check whether Vars
		 * coming from the RHS must be non-null because of table constraints.
		 * That seems complicated and expensive though (in particular, one
		 * would have to be wary of lower outer joins). For the moment this
		 * seems sufficient.
		 */
		if (jointype == JOIN_LEFT)
		{
			List	   *overlap;

			local_nonnullable_vars = find_nonnullable_vars(j->quals);
			computed_local_nonnullable_vars = true;

			/*
			 * It's not sufficient to check whether local_nonnullable_vars and
			 * forced_null_vars overlap: we need to know if the overlap
			 * includes any RHS variables.
			 */
			overlap = list_intersection(local_nonnullable_vars,
										forced_null_vars);
			if (overlap != NIL &&
				bms_overlap(pull_varnos((Node *) overlap),
							right_state->relids))
				jointype = JOIN_ANTI;
		}

		/* Apply the jointype change, if any, to both jointree node and RTE */
		if (rtindex && jointype != j->jointype)
		{
			RangeTblEntry *rte = rt_fetch(rtindex, root->parse->rtable);

			Assert(rte->rtekind == RTE_JOIN);
			Assert(rte->jointype == j->jointype);
			rte->jointype = jointype;
		}
		j->jointype = jointype;

		/* Only recurse if there's more to do below here */
		if (left_state->contains_outer || right_state->contains_outer)
		{
			Relids		local_nonnullable_rels;
			List	   *local_forced_null_vars;
			Relids		pass_nonnullable_rels;
			List	   *pass_nonnullable_vars;
			List	   *pass_forced_null_vars;

			/*
			 * If this join is (now) inner, we can add any constraints its
			 * quals provide to those we got from above.  But if it is outer,
			 * we can pass down the local constraints only into the nullable
			 * side, because an outer join never eliminates any rows from its
			 * non-nullable side.  Also, there is no point in passing upper
			 * constraints into the nullable side, since if there were any
			 * we'd have been able to reduce the join.  (In the case of upper
			 * forced-null constraints, we *must not* pass them into the
			 * nullable side --- they either applied here, or not.) The upshot
			 * is that we pass either the local or the upper constraints,
			 * never both, to the children of an outer join.
			 *
			 * Note that a SEMI join works like an inner join here: it's okay
			 * to pass down both local and upper constraints.  (There can't be
			 * any upper constraints affecting its inner side, but it's not
			 * worth having a separate code path to avoid passing them.)
			 *
			 * At a FULL join we just punt and pass nothing down --- is it
			 * possible to be smarter?
			 */
			if (jointype != JOIN_FULL)
			{
				local_nonnullable_rels = find_nonnullable_rels(j->quals);
				if (!computed_local_nonnullable_vars)
					local_nonnullable_vars = find_nonnullable_vars(j->quals);
				local_forced_null_vars = find_forced_null_vars(j->quals);
				if (jointype == JOIN_INNER || jointype == JOIN_SEMI)
				{
					/* OK to merge upper and local constraints */
					local_nonnullable_rels = bms_add_members(local_nonnullable_rels,
														   nonnullable_rels);
					local_nonnullable_vars = list_concat(local_nonnullable_vars,
														 nonnullable_vars);
					local_forced_null_vars = list_concat(local_forced_null_vars,
														 forced_null_vars);
				}
			}
			else
			{
				/* no use in calculating these */
				local_nonnullable_rels = NULL;
				local_forced_null_vars = NIL;
			}

			if (left_state->contains_outer)
			{
				if (jointype == JOIN_INNER || jointype == JOIN_SEMI)
				{
					/* pass union of local and upper constraints */
					pass_nonnullable_rels = local_nonnullable_rels;
					pass_nonnullable_vars = local_nonnullable_vars;
					pass_forced_null_vars = local_forced_null_vars;
				}
				else if (jointype != JOIN_FULL) /* ie, LEFT or ANTI */
				{
					/* can't pass local constraints to non-nullable side */
					pass_nonnullable_rels = nonnullable_rels;
					pass_nonnullable_vars = nonnullable_vars;
					pass_forced_null_vars = forced_null_vars;
				}
				else
				{
					/* no constraints pass through JOIN_FULL */
					pass_nonnullable_rels = NULL;
					pass_nonnullable_vars = NIL;
					pass_forced_null_vars = NIL;
				}
				reduce_outer_joins_pass2(j->larg, left_state, root,
										 pass_nonnullable_rels,
										 pass_nonnullable_vars,
										 pass_forced_null_vars);
			}

			if (right_state->contains_outer)
			{
				if (jointype != JOIN_FULL)		/* ie, INNER/LEFT/SEMI/ANTI */
				{
					/* pass appropriate constraints, per comment above */
					pass_nonnullable_rels = local_nonnullable_rels;
					pass_nonnullable_vars = local_nonnullable_vars;
					pass_forced_null_vars = local_forced_null_vars;
				}
				else
				{
					/* no constraints pass through JOIN_FULL */
					pass_nonnullable_rels = NULL;
					pass_nonnullable_vars = NIL;
					pass_forced_null_vars = NIL;
				}
				reduce_outer_joins_pass2(j->rarg, right_state, root,
										 pass_nonnullable_rels,
										 pass_nonnullable_vars,
										 pass_forced_null_vars);
			}
			bms_free(local_nonnullable_rels);
		}
	}
	else
		elog(ERROR, "unrecognized node type: %d",
			 (int) nodeTag(jtnode));
}

/*
 * substitute_multiple_relids - adjust node relid sets after pulling up
 * a subquery
 *
 * Find any PlaceHolderVar nodes in the given tree that reference the
 * pulled-up relid, and change them to reference the replacement relid(s).
 *
 * NOTE: although this has the form of a walker, we cheat and modify the
 * nodes in-place.	This should be OK since the tree was copied by
 * pullup_replace_vars earlier.  Avoid scribbling on the original values of
 * the bitmapsets, though, because expression_tree_mutator doesn't copy those.
 */

typedef struct
{
	int			varno;
	int			sublevels_up;
	Relids		subrelids;
} substitute_multiple_relids_context;

static bool
substitute_multiple_relids_walker(Node *node,
								  substitute_multiple_relids_context *context)
{
	if (node == NULL)
		return false;
	if (IsA(node, PlaceHolderVar))
	{
		PlaceHolderVar *phv = (PlaceHolderVar *) node;

		if (phv->phlevelsup == context->sublevels_up &&
			bms_is_member(context->varno, phv->phrels))
		{
			phv->phrels = bms_union(phv->phrels,
									context->subrelids);
			phv->phrels = bms_del_member(phv->phrels,
										 context->varno);
		}
		/* fall through to examine children */
	}
	if (IsA(node, Query))
	{
		/* Recurse into subselects */
		bool		result;

		context->sublevels_up++;
		result = query_tree_walker((Query *) node,
								   substitute_multiple_relids_walker,
								   (void *) context, 0);
		context->sublevels_up--;
		return result;
	}
	/* Shouldn't need to handle planner auxiliary nodes here */
	Assert(!IsA(node, SpecialJoinInfo));
	Assert(!IsA(node, AppendRelInfo));
	Assert(!IsA(node, PlaceHolderInfo));
	Assert(!IsA(node, MinMaxAggInfo));

	return expression_tree_walker(node, substitute_multiple_relids_walker,
								  (void *) context);
}

static void
substitute_multiple_relids(Node *node, int varno, Relids subrelids)
{
	substitute_multiple_relids_context context;

	context.varno = varno;
	context.sublevels_up = 0;
	context.subrelids = subrelids;

	/*
	 * Must be prepared to start with a Query or a bare expression tree.
	 */
	query_or_expression_tree_walker(node,
									substitute_multiple_relids_walker,
									(void *) &context,
									0);
}

/*
 * fix_append_rel_relids: update RT-index fields of AppendRelInfo nodes
 *
 * When we pull up a subquery, any AppendRelInfo references to the subquery's
 * RT index have to be replaced by the substituted relid (and there had better
 * be only one).  We also need to apply substitute_multiple_relids to their
 * translated_vars lists, since those might contain PlaceHolderVars.
 *
 * We assume we may modify the AppendRelInfo nodes in-place.
 */
static void
fix_append_rel_relids(List *append_rel_list, int varno, Relids subrelids)
{
	ListCell   *l;
	int			subvarno = -1;

	/*
	 * We only want to extract the member relid once, but we mustn't fail
	 * immediately if there are multiple members; it could be that none of the
	 * AppendRelInfo nodes refer to it.  So compute it on first use. Note that
	 * bms_singleton_member will complain if set is not singleton.
	 */
	foreach(l, append_rel_list)
	{
		AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(l);

		/* The parent_relid shouldn't ever be a pullup target */
		Assert(appinfo->parent_relid != varno);

		if (appinfo->child_relid == varno)
		{
			if (subvarno < 0)
				subvarno = bms_singleton_member(subrelids);
			appinfo->child_relid = subvarno;
		}

		/* Also finish fixups for its translated vars */
		substitute_multiple_relids((Node *) appinfo->translated_vars,
								   varno, subrelids);
	}
}

/*
 * get_relids_in_jointree: get set of RT indexes present in a jointree
 *
 * If include_joins is true, join RT indexes are included; if false,
 * only base rels are included.
 */
Relids
get_relids_in_jointree(Node *jtnode, bool include_joins)
{
	Relids		result = NULL;

	if (jtnode == NULL)
		return result;
	if (IsA(jtnode, RangeTblRef))
	{
		int			varno = ((RangeTblRef *) jtnode)->rtindex;

		result = bms_make_singleton(varno);
	}
	else if (IsA(jtnode, FromExpr))
	{
		FromExpr   *f = (FromExpr *) jtnode;
		ListCell   *l;

		foreach(l, f->fromlist)
		{
			result = bms_join(result,
							  get_relids_in_jointree(lfirst(l),
													 include_joins));
		}
	}
	else if (IsA(jtnode, JoinExpr))
	{
		JoinExpr   *j = (JoinExpr *) jtnode;

		result = get_relids_in_jointree(j->larg, include_joins);
		result = bms_join(result,
						  get_relids_in_jointree(j->rarg, include_joins));
		if (include_joins && j->rtindex)
			result = bms_add_member(result, j->rtindex);
	}
	else
		elog(ERROR, "unrecognized node type: %d",
			 (int) nodeTag(jtnode));
	return result;
}

/*
 * get_relids_for_join: get set of base RT indexes making up a join
 */
Relids
get_relids_for_join(PlannerInfo *root, int joinrelid)
{
	Node	   *jtnode;

	jtnode = find_jointree_node_for_rel((Node *) root->parse->jointree,
										joinrelid);
	if (!jtnode)
		elog(ERROR, "could not find join node %d", joinrelid);
	return get_relids_in_jointree(jtnode, false);
}

/*
 * find_jointree_node_for_rel: locate jointree node for a base or join RT index
 *
 * Returns NULL if not found
 */
static Node *
find_jointree_node_for_rel(Node *jtnode, int relid)
{
	if (jtnode == NULL)
		return NULL;
	if (IsA(jtnode, RangeTblRef))
	{
		int			varno = ((RangeTblRef *) jtnode)->rtindex;

		if (relid == varno)
			return jtnode;
	}
	else if (IsA(jtnode, FromExpr))
	{
		FromExpr   *f = (FromExpr *) jtnode;
		ListCell   *l;

		foreach(l, f->fromlist)
		{
			jtnode = find_jointree_node_for_rel(lfirst(l), relid);
			if (jtnode)
				return jtnode;
		}
	}
	else if (IsA(jtnode, JoinExpr))
	{
		JoinExpr   *j = (JoinExpr *) jtnode;

		if (relid == j->rtindex)
			return jtnode;
		jtnode = find_jointree_node_for_rel(j->larg, relid);
		if (jtnode)
			return jtnode;
		jtnode = find_jointree_node_for_rel(j->rarg, relid);
		if (jtnode)
			return jtnode;
	}
	else
		elog(ERROR, "unrecognized node type: %d",
			 (int) nodeTag(jtnode));
	return NULL;
}