sqlalchemy / CHANGES

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0.3.8
- engines
    - added detach() to Connection, allows underlying DBAPI connection
      to be detached from its pool, closing on dereference/close()
      instead of being reused by the pool.
    - added invalidate() to Connection, immediately invalidates the
      Connection and its underlying DBAPI connection.
- sql
    - _Label class overrides compare_self to return its ultimate
      object. meaning, if you say someexpr.label('foo') == 5, it
      produces the correct "someexpr == 5".
    - _Label propigates "_hide_froms()" so that scalar selects
      behave more properly with regards to FROM clause #574 
    - fix to long name generation when using oid_column as an order by
      (oids used heavily in mapper queries)
    - significant speed improvement to ResultProxy, pre-caches
      TypeEngine dialect implementations and saves on function calls
      per column
    - parenthesis are applied to clauses via a new _Grouping
      construct. uses operator precedence to more intelligently apply
      parenthesis to clauses, provides cleaner nesting of clauses
      (doesnt mutate clauses placed in other clauses, i.e. no 'parens'
      flag)
    - added 'modifier' keyword, works like func.<foo> except does not
      add parenthesis.  e.g. select([modifier.DISTINCT(...)]) etc.
    - removed "no group by's in a select thats part of a UNION"
      restriction [ticket:578]
- orm
    - added reset_joinpoint() method to Query, moves the "join point"
      back to the starting mapper. 0.4 will change the behavior of
      join() to reset the "join point" in all cases so this is an
      interim method. for forwards compatibility, ensure joins across
      multiple relations are specified using a single join(), i.e.
      join(['a', 'b', 'c']).
    - fixed bug in query.instances() that wouldnt handle more than
      on additional mapper or one additional column.
    - "delete-orphan" no longer implies "delete". ongoing effort to 
      separate the behavior of these two operations.
    - many-to-many relationships properly set the type of bind params
      for delete operations on the association table
    - many-to-many relationships check that the number of rows deleted
      from the association table by a delete operation matches the
      expected results
    - session.get() and session.load() propigate **kwargs through to
      query
    - fix to polymorphic query which allows the original
      polymorphic_union to be embedded into a correlated subquery
      [ticket:577]
    - fix to select_by(<propname>=<object instance>) -style joins in
      conjunction with many-to-many relationships, bug introduced in
      r2556
    - the "primary_key" argument to mapper() is propigated to the
      "polymorphic" mapper. primary key columns in this list get
      normalized to that of the mapper's local table.
    - restored logging of "lazy loading clause" under
      sa.orm.strategies logger, got removed in 0.3.7
    - improved support for eagerloading of properties off of mappers
      that are mapped to select() statements; i.e. eagerloader is
      better at locating the correct selectable with which to attach
      its LEFT OUTER JOIN.
- mysql
    - Nearly all MySQL column types are now supported for declaration
      and reflection. Added NCHAR, NVARCHAR, VARBINARY, TINYBLOB,
      LONGBLOB, YEAR
    - The sqltypes.Binary passthrough now always builds a BLOB,
      avoiding problems with very old database versions
    - support for column-level CHARACTER SET and COLLATE declarations,
      as well as ASCII, UNICODE, NATIONAL and BINARY shorthand.
- firebird
    - set max identifier length to 31
    - supports_sane_rowcount() set to False due to ticket #370.
      versioned_id_col feature wont work in FB.
    - some execution fixes
-extensions
    - new association proxy implementation, implementing complete
      proxies to list, dict and set-based relation collections
    - added orderinglist, a custom list class that synchronizes an
      object attribute with that object's position in the list
    - small fix to SelectResultsExt to not bypass itself during
      select().
    - added filter(), filter_by() to assignmapper

0.3.7
- engines
    - warnings module used for issuing warnings (instead of logging)
    - cleanup of DBAPI import strategies across all engines 
      [ticket:480]
    - refactoring of engine internals which reduces complexity,
      number of codepaths; places more state inside of ExecutionContext
      to allow more dialect control of cursor handling, result sets.
      ResultProxy totally refactored and also has two versions of
      "buffered" result sets used for different purposes.
    - server side cursor support fully functional in postgres
      [ticket:514].
    - improved framework for auto-invalidation of connections that have
      lost their underlying database, via dialect-specific detection
      of exceptions corresponding to that database's disconnect
      related error messages.  Additionally, when a "connection no 
      longer open" condition is detected, the entire connection pool 
      is discarded and replaced with a new instance.  #516
    - the dialects within sqlalchemy.databases become a setuptools
      entry points. loading the built-in database dialects works the
      same as always, but if none found will fall back to trying
      pkg_resources to load an external module [ticket:521]
    - Engine contains a "url" attribute referencing the url.URL object
      used by create_engine().
- sql:
    - keys() of result set columns are not lowercased, come back
      exactly as they're expressed in cursor.description.  note this
      causes colnames to be all caps in oracle.
    - preliminary support for unicode table names, column names and 
      SQL statements added, for databases which can support them.
      Works with sqlite and postgres so far.  Mysql *mostly* works
      except the has_table() function does not work.  Reflection
      works too.
    - the Unicode type is now a direct subclass of String, which now
      contains all the "convert_unicode" logic.  This helps the variety
      of unicode situations that occur in db's such as MS-SQL to be
      better handled and allows subclassing of the Unicode datatype.
      [ticket:522]
    - ClauseElements can be used in in_() clauses now, such as bind 
      parameters, etc. #476
    - reverse operators implemented for `CompareMixin` elements,
      allows expressions like "5 + somecolumn" etc. #474
    - the "where" criterion of an update() and delete() now correlates
      embedded select() statements against the table being updated or
      deleted.  this works the same as nested select() statement
      correlation, and can be disabled via the correlate=False flag on 
      the embedded select().
    - column labels are now generated in the compilation phase, which
      means their lengths are dialect-dependent.  So on oracle a label
      that gets truncated to 30 chars will go out to 63 characters
      on postgres.  Also, the true labelname is always attached as the
      accessor on the parent Selectable so theres no need to be aware
      of the "truncated" label names [ticket:512].
    - column label and bind param "truncation" also generate 
      deterministic names now, based on their ordering within the 
      full statement being compiled.  this means the same statement
      will produce the same string across application restarts and
      allowing DB query plan caching to work better.
    - the "mini" column labels generated when using subqueries, which
      are to work around glitchy SQLite behavior that doesnt understand
      "foo.id" as equivalent to "id", are now only generated in the case 
      that those named columns are selected from (part of [ticket:513])
    - the label() method on ColumnElement will properly propigate the
      TypeEngine of the base element out to the label, including a label()
      created from a scalar=True select() statement.
    - MS-SQL better detects when a query is a subquery and knows not to
      generate ORDER BY phrases for those [ticket:513]
    - fix for fetchmany() "size" argument being positional in most
      dbapis [ticket:505]
    - sending None as an argument to func.<something> will produce
      an argument of NULL
    - query strings in unicode URLs get keys encoded to ascii
      for **kwargs compat
    - slight tweak to raw execute() change to also support tuples
      for positional parameters, not just lists [ticket:523]
    - fix to case() construct to propigate the type of the first
      WHEN condition as the return type of the case statement
- orm:
    - fixed critical issue when, after options(eagerload()) is used,
      the mapper would then always apply query "wrapping" behavior
      for all subsequent LIMIT/OFFSET/DISTINCT queries, even if no
      eager loading was applied on those subsequent queries.
    - added query.with_parent(someinstance) method.  searches for
      target instance using lazy join criterion from parent instance.
      takes optional string "property" to isolate the desired relation.
      also adds static Query.query_from_parent(instance, property)
      version. [ticket:541]
    - improved query.XXX_by(someprop=someinstance) querying to use
      similar methodology to with_parent, i.e. using the "lazy" clause
      which prevents adding the remote instance's table to the SQL, 
      thereby making more complex conditions possible [ticket:554]
    - added generative versions of aggregates, i.e. sum(), avg(), etc.
      to query. used via query.apply_max(), apply_sum(), etc. 
      #552
    - fix to using distinct() or distinct=True in combination with 
      join() and similar
    - corresponding to label/bindparam name generation, eager loaders 
      generate deterministic names for the aliases they create using 
      md5 hashes.
    - improved/fixed custom collection classes when giving it "set"/
      "sets.Set" classes or subclasses (was still looking for append()
      methods on them during lazy loads)
    - restored old "column_property()" ORM function (used to be called
      "column()") to force any column expression to be added as a property
      on a mapper, particularly those that aren't present in the mapped
      selectable.  this allows "scalar expressions" of any kind to be
      added as relations (though they have issues with eager loads).
    - fix to many-to-many relationships targeting polymorphic mappers
      [ticket:533]
    - making progress with session.merge() as well as combining its
      usage with entity_name [ticket:543]
    - the usual adjustments to relationships between inheriting mappers,
      in this case establishing relation()s to subclass mappers where
      the join conditions come from the superclass' table
- informix:
    - informix support added !  courtesy James Zhang, who put a ton
      of effort in.
- sqlite:
    - removed silly behavior where sqlite would reflect UNIQUE indexes
      as part of the primary key (?!)
- oracle:
    - small fix to allow successive compiles of the same SELECT object
      which features LIMIT/OFFSET.  oracle dialect needs to modify
      the object to have ROW_NUMBER OVER and wasn't performing 
      the full series of steps on successive compiles.
- mysql
    - support for SSL arguments given as inline within URL query string,
      prefixed with "ssl_", courtesy terjeros@gmail.com.
    - mysql uses "DESCRIBE [<schemaname>].<tablename>", catching exceptions
      if table doesnt exist, in order to determine if a table exists.
      this supports unicode table names as well as schema names. tested
      with MySQL5 but should work with 4.1 series as well. (#557)
- extensions
    - big fix to AssociationProxy so that multiple AssociationProxy
      objects can be associated with a single association collection. 
    - assign_mapper names methods according to their keys (i.e. __name__)
      #551
- mssql
    - pyodbc is now the preferred DB-API for MSSQL, and if no module is 
      specifically requested, will be loaded first on a module probe.

    - The @@SCOPE_IDENTITY is now used instead of @@IDENTITY. This 
      behavior may be overridden with the engine_connect
      "use_scope_identity" keyword parameter, which may also be specified 
      in the dburi.


     
0.3.6
- sql:
    - bindparam() names are now repeatable!  specify two
      distinct bindparam()s with the same name in a single statement,
      and the key will be shared.  proper positional/named args translate
      at compile time.  for the old behavior of "aliasing" bind parameters
      with conflicting names, specify "unique=True" - this option is
      still used internally for all the auto-genererated (value-based) 
      bind parameters.    
    
    - slightly better support for bind params as column clauses, either
      via bindparam() or via literal(), i.e. select([literal('foo')])

    - MetaData can bind to an engine either via "url" or "engine" kwargs
      to constructor, or by using connect() method. BoundMetaData is
      identical to MetaData except engine_or_url param is required.
      DynamicMetaData is the same and provides thread-local connections be
      default.
    
    - exists() becomes useable as a standalone selectable, not just in a
      WHERE clause, i.e. exists([columns], criterion).select()

    - correlated subqueries work inside of ORDER BY, GROUP BY

    - fixed function execution with explicit connections, i.e.
      conn.execute(func.dosomething())

    - use_labels flag on select() wont auto-create labels for literal text
      column elements, since we can make no assumptions about the text. to
      create labels for literal columns, you can say "somecol AS
      somelabel", or use literal_column("somecol").label("somelabel")

    - quoting wont occur for literal columns when they are "proxied" into
      the column collection for their selectable (is_literal flag is
      propigated). literal columns are specified via
      literal_column("somestring").

    - added "fold_equivalents" boolean argument to Join.select(), which
      removes 'duplicate' columns from the resulting column clause that
      are known to be equivalent based on the join condition. this is of
      great usage when constructing subqueries of joins which Postgres
      complains about if duplicate column names are present.

    - fixed use_alter flag on ForeignKeyConstraint [ticket:503]

    - fixed usage of 2.4-only "reversed" in topological.py [ticket:506]

    - for hackers, refactored the "visitor" system of ClauseElement and
      SchemaItem so that the traversal of items is controlled by the
      ClauseVisitor itself, using the method visitor.traverse(item).
      accept_visitor() methods can still be called directly but will not
      do any traversal of child items. ClauseElement/SchemaItem now have a
      configurable get_children() method to return the collection of child
      elements for each parent object. This allows the full traversal of
      items to be clear and unambiguous (as well as loggable), with an
      easy method of limiting a traversal (just pass flags which are
      picked up by appropriate get_children() methods). [ticket:501]

    - the "else_" parameter to the case statement now properly works when
      set to zero.

- orm:
    - the full featureset of the SelectResults extension has been merged
      into a new set of methods available off of Query.  These methods
      all provide "generative" behavior, whereby the Query is copied
      and a new one returned with additional criterion added.  
      The new methods include:

          filter() - applies select criterion to the query
          filter_by() - applies "by"-style criterion to the query
          avg() - return the avg() function on the given column
          join() - join to a property (or across a list of properties)
          outerjoin() - like join() but uses LEFT OUTER JOIN
          limit()/offset() - apply LIMIT/OFFSET
          range-based access which applies limit/offset:  
             session.query(Foo)[3:5]
          distinct() - apply DISTINCT
          list() - evaluate the criterion and return results
          
      no incompatible changes have been made to Query's API and no methods
      have been deprecated.  Existing methods like select(), select_by(),
      get(), get_by() all execute the query at once and return results
      like they always did.  join_to()/join_via() are still there although
      the generative join()/outerjoin() methods are easier to use.
      
    - the return value for multiple mappers used with instances() now
      returns a cartesian product of the requested list of mappers,
      represented as a list of tuples. this corresponds to the documented
      behavior. So that instances match up properly, the "uniquing" is
      disabled when this feature is used.

    - Query has add_entity() and add_column() generative methods. these
      will add the given mapper/class or ColumnElement to the query at
      compile time, and apply them to the instances() method. the user is
      responsible for constructing reasonable join conditions (otherwise
      you can get full cartesian products). result set is the list of
      tuples, non-uniqued.

    - strings and columns can also be sent to the *args of instances()
      where those exact result columns will be part of the result tuples.

    - a full select() construct can be passed to query.select() (which
      worked anyway), but also query.selectfirst(), query.selectone()
      which will be used as is (i.e. no query is compiled). works
      similarly to sending the results to instances().

    - eager loading will not "aliasize" "order by" clauses that were
      placed in the select statement by something other than the eager
      loader itself, to fix possibility of dupe columns as illustrated in
      [ticket:495]. however, this means you have to be more careful with
      the columns placed in the "order by" of Query.select(), that you
      have explicitly named them in your criterion (i.e. you cant rely on
      the eager loader adding them in for you)
      
    - added a handy multi-use "identity_key()" method to Session, allowing
      the generation of identity keys for primary key values, instances,
      and rows, courtesy Daniel Miller

    - many-to-many table will be properly handled even for operations that
      occur on the "backref" side of the operation [ticket:249]

    - added "refresh-expire" cascade [ticket:492].  allows refresh() and
      expire() calls to propigate along relationships.
    
    - more fixes to polymorphic relations, involving proper lazy-clause
      generation on many-to-one relationships to polymorphic mappers 
      [ticket:493]. also fixes to detection of "direction", more specific
      targeting of columns that belong to the polymorphic union vs. those
      that dont.
      
    - some fixes to relationship calcs when using "viewonly=True" to pull
      in other tables into the join condition which arent parent of the
      relationship's parent/child mappings

    - flush fixes on cyclical-referential relationships that contain
      references to other instances outside of the cyclical chain, when
      some of the objects in the cycle are not actually part of the flush
      
    - put an aggressive check for "flushing object A with a collection of
      B's, but you put a C in the collection" error condition - **even if
      C is a subclass of B**, unless B's mapper loads polymorphically.
      Otherwise, the collection will later load a "B" which should be a
      "C" (since its not polymorphic) which breaks in bi-directional
      relationships (i.e. C has its A, but A's backref will lazyload it as
      a different instance of type "B") [ticket:500] This check is going
      to bite some of you who do this without issues, so the error message
      will also document a flag "enable_typechecks=False" to disable this
      checking. But be aware that bi-directional relationships in
      particular become fragile without this check.

- extensions:
    - options() method on SelectResults now implemented "generatively"
      like the rest of the SelectResults methods [ticket:472].  But
      you're going to just use Query now anyway.

    - query() method is added by assignmapper.  this helps with 
      navigating to all the new generative methods on Query.

- ms-sql:
    - removed seconds input on DATE column types (probably 
        should remove the time altogether)

    - null values in float fields no longer raise errors

    - LIMIT with OFFSET now raises an error (MS-SQL has no OFFSET support)

    - added an facility to use the MSSQL type VARCHAR(max) instead of TEXT 
      for large unsized string fields. Use the new "text_as_varchar" to 
      turn it on. [ticket:509]

    - ORDER BY clauses without a LIMIT are now stripped in subqueries, as 
      MS-SQL forbids this usage

    - cleanup of module importing code; specifiable DB-API module; more 
      explicit ordering of module preferences. [ticket:480]

- oracle:
    - got binary working for any size input !  cx_oracle works fine,
      it was my fault as BINARY was being passed and not BLOB for
      setinputsizes (also unit tests werent even setting input sizes).

    - also fixed CLOB read/write on a separate changeset.

    - auto_setinputsizes defaults to True for Oracle, fixed cases where
      it improperly propigated bad types.

- mysql:
    - added a catchall **kwargs to MSString, to help reflection of 
      obscure types (like "varchar() binary" in MS 4.0)

    - added explicit MSTimeStamp type which takes effect when using 
      types.TIMESTAMP.

    
0.3.5
- sql:
    - the value of "case_sensitive" defaults to True now, regardless of the
      casing of the identifier, unless specifically set to False. this is
      because the object might be label'ed as something else which does
      contain mixed case, and propigating "case_sensitive=False" breaks that.
      Other fixes to quoting when using labels and "fake" column objects
    - added a "supports_execution()" method to ClauseElement, so that
      individual kinds of clauses can express if they are appropriate for
      executing...such as, you can execute a "select", but not a "Table" or a
      "Join".
    - fixed argument passing to straight textual execute() on engine,
      connection. can handle *args or a list instance for positional, **kwargs
      or a dict instance for named args, or a list of list or dicts to invoke
      executemany()
    - small fix to BoundMetaData to accept unicode or string URLs
    - fixed named PrimaryKeyConstraint generation [ticket:466] courtesy
      andrija at gmail
    - fixed generation of CHECK constraints on columns [ticket:464]
    - fixes to tometadata() operation to propigate Constraints at column and
      table level
- oracle:
    - when returning "rowid" as the ORDER BY column or in use with ROW_NUMBER
      OVER, oracle dialect checks the selectable its being applied to and will
      switch to table PK if not applicable, i.e. for a UNION. checking for
      DISTINCT, GROUP BY (other places that rowid is invalid) still a TODO.
      allows polymorphic mappings to function, [ticket:436]
    - sequences on a non-pk column will properly fire off on INSERT
    - added PrefetchingResultProxy support to pre-fetch LOB columns when they
      are known to be present, fixes [ticket:435]
    - implemented reflection of tables based on synonyms, including across
      dblinks [ticket:379]
    - issues a log warning when a related table cant be reflected due to
      certain permission errors [ticket:363]
- mysql:
    - fix to reflection on older DB's that might return array() type for 
    "show variables like" statements
- postgres:
    - better reflection of sequences for alternate-schema Tables [ticket:442]
    - sequences on a non-pk column will properly fire off on INSERT
    - added PGInterval type [ticket:460], PGInet type [ticket:444]
- mssql:
    - preliminary support for pyodbc (Yay!) [ticket:419]
    - better support for NVARCHAR types added [ticket:298]
    - fix for commit logic on pymssql
    - fix for query.get() with schema [ticket:456]
    - fix for non-integer relationships [ticket:473]
    - DB-API module now selectable at run-time [ticket:419]
    - now passes many more unit tests [tickets:422, 481, 415]
    - better unittest compatibility with ANSI functions [ticket:479]
    - improved support for implicit sequence PK columns with auto-insert
      [ticket:415]
    - fix for blank password in adodbapi [ticket:371]
    - fixes to get unit tests working with pyodbc [ticket:481]
    - fix to auto_identity_insert on db-url query
    - added query_timeout to db-url query parms. currently works only for
      pymssql
    - tested with pymssql 0.8.0 (which is now LGPL)
- orm bugs:
    - another refactoring to relationship calculation. Allows more accurate
      ORM behavior with relationships from/to/between mappers, particularly
      polymorphic mappers, also their usage with Query, SelectResults. tickets
      include [ticket:439], [ticket:441], [ticket:448].
    - removed deprecated method of specifying custom collections on classes;
      you must now use the "collection_class" option. the old way was
      beginning to produce conflicts when people used assign_mapper(), which
      now patches an "options" method, in conjunction with a relationship
      named "options". (relationships take precedence over monkeypatched
      assign_mapper methods).
    - extension() query option propigates to Mapper._instance() method so that
      all loading-related methods get called [ticket:454]
    - eager relation to an inheriting mapper wont fail if no rows returned for
      the relationship.
    - eager relation loading bug fixed for eager relation on multiple
      descendant classes [ticket:486]
    - fix for very large topological sorts, courtesy ants.aasma at gmail
      [ticket:423]
    - eager loading is slightly more strict about detecting "self-referential"
      relationships, specifically between polymorphic mappers. this results in
      an "eager degrade" to lazy loading.
    - improved support for complex queries embedded into "where" criterion for
      query.select() [ticket:449]
    - mapper options like eagerload(), lazyload(), deferred(), will work for
      "synonym()" relationships [ticket:485]
    - fixed bug where cascade operations incorrectly included deleted
      collection items in the cascade [ticket:445]
    - fixed relationship deletion error when one-to-many child item is moved
      to a new parent in a single unit of work [ticket:478]
    - fixed relationship deletion error where parent/child with a single
      column as PK/FK on the child would raise a "blank out the primary key"
      error, if manually deleted or "delete" cascade without "delete-orphan"
      was used
    - fix to deferred so that load operation doesnt mistakenly occur when only
      PK col attributes are set
- orm enhancements:
    - implemented foreign_keys argument to mapper [ticket:385]. use in
      conjunction with primaryjoin/secondaryjoin arguments to specify/override
      foreign keys defined on the Table instance.
    - contains_eager('foo') automatically implies eagerload('foo')
    - added "alias" argument to contains_eager(). use it to specify the string
      name or Alias instance of an alias used in the query for the eagerly
      loaded child items. easier to use than "decorator"
    - added "contains_alias()" option for result set mapping to an alias of
      the mapped table
    - added support for py2.5 "with" statement with SessionTransaction
      [ticket:468]
- extensions:
    - added distinct() method to SelectResults. generally should only make a
      difference when using count().
    - added options() method to SelectResults, equivalent to query.options()
      [ticket:472]
    - added optional __table_opts__ dictionary to ActiveMapper, will send kw
      options to Table objects [ticket:462]
    - added selectfirst(), selectfirst_by() to assign_mapper [ticket:467]

0.3.4
- general:
  - global "insure"->"ensure" change. in US english "insure" is actually
    largely interchangeable with "ensure" (so says the dictionary), so I'm not
    completely illiterate, but its definitely sub-optimal to "ensure" which is
    non-ambiguous.
- sql:
  - added "fetchmany()" support to ResultProxy
  - added support for column "key" attribute to be useable in
    row[<key>]/row.<key>
  - changed "BooleanExpression" to subclass from "BinaryExpression", so that
    boolean expressions can also follow column-clause behaviors (i.e. label(),
    etc).
  - trailing underscores are trimmed from func.<xxx> calls, such as func.if_()
  - fix to correlation of subqueries when the column list of the select
    statement is constructed with individual calls to append_column(); this
    fixes an ORM bug whereby nested select statements were not getting
    correlated with the main select generated by the Query object.
  - another fix to subquery correlation so that a subquery which has only one
    FROM element will *not* correlate that single element, since at least one
    FROM element is required in a query.
  - default "timezone" setting is now False. this corresponds to Python's
    datetime behavior as well as Postgres' timestamp/time types (which is the
    only timezone-sensitive dialect at the moment) [ticket:414]
  - the "op()" function is now treated as an "operation", rather than a
    "comparison". the difference is, an operation produces a BinaryExpression
    from which further operations can occur whereas comparison produces the
    more restrictive BooleanExpression
  - trying to redefine a reflected primary key column as non-primary key raises
    an error
  - type system slightly modified to support TypeDecorators that can be
    overridden by the dialect (ok, thats not very clear, it allows the mssql
    tweak below to be possible)
- mssql:
  - added an NVarchar type (produces NVARCHAR), also MSUnicode which provides
    Unicode-translation for the NVarchar regardless of dialect convert_unicode
    setting.
- postgres:
  - fix to the initial checkfirst for tables to take current schema into
    account [ticket:424]
  - postgres has an optional "server_side_cursors=True" flag which will utilize
    server side cursors. these are appropriate for fetching only partial
    results and are necessary for working with very large unbounded result
    sets. While we'd like this to be the default behavior, different
    environments seem to have different results and the causes have not been
    isolated so we are leaving the feature off by default for now. Uses an
    apparently undocumented psycopg2 behavior recently discovered on the
    psycopg mailing list.
  - added "BIGSERIAL" support for postgres table with
    PGBigInteger/autoincrement
  - fixes to postgres reflection to better handle when schema names are
    present; thanks to jason (at) ncsmags.com [ticket:402]
- mysql:
  - mysql is inconsistent with what kinds of quotes it uses in foreign keys
    during a SHOW CREATE TABLE, reflection updated to accomodate for all three
    styles [ticket:420]
  - mysql table create options work on a generic passthru now, i.e. Table(...,
    mysql_engine='InnoDB', mysql_collate="latin1_german2_ci",
    mysql_auto_increment="5", mysql_<somearg>...), helps [ticket:418]
- firebird:
  - order of constraint creation puts primary key first before all other
    constraints; required for firebird, not a bad idea for others [ticket:408]
  - Firebird fix to autoload multifield foreign keys [ticket:409]
  - Firebird NUMERIC type properly handles a type without precision
    [ticket:409]
- oracle:
  - *slight* support for binary, but still need to figure out how to insert
    reasonably large values (over 4K). requires auto_setinputsizes=True sent to
    create_engine(), rows must be fully fetched individually, etc.
- orm:
  - poked the first hole in the can of worms: saying
    query.select_by(somerelationname=someinstance) will create the join of the
    primary key columns represented by "somerelationname"'s mapper to the
    actual primary key in "someinstance".
  - reworked how relations interact with "polymorphic" mappers, i.e. mappers
    that have a select_table as well as polymorphic flags. better determination
    of proper join conditions, interaction with user- defined join conditions,
    and support for self-referential polymorphic mappers.
  - related to polymorphic mapping relations, some deeper error checking when
    compiling relations, to detect an ambiguous "primaryjoin" in the case that
    both sides of the relationship have foreign key references in the primary
    join condition. also tightened down conditions used to locate "relation
    direction", associating the "foreignkey" of the relationship with the
    "primaryjoin"
  - a little bit of improvement to the concept of a "concrete" inheritance
    mapping, though that concept is not well fleshed out yet (added test case
    to support concrete mappers on top of a polymorphic base).
  - fix to "proxy=True" behavior on synonym()
  - fixed bug where delete-orphan basically didn't work with many-to-many
    relationships [ticket:427], backref presence generally hid the symptom
  - added a mutex to the mapper compilation step. ive been reluctant to add any
    kind of threading anything to SA but this is one spot that its its really
    needed since mappers are typically "global", and while their state does not
    change during normal operation, the initial compilation step does modify
    internal state significantly, and this step usually occurs not at
    module-level initialization time (unless you call compile()) but at
    first-request time
  - basic idea of "session.merge()" actually implemented.  needs more testing.
  - added "compile_mappers()" function as a shortcut to compiling all mappers
  - fix to MapperExtension create_instance so that entity_name properly
    associated with new instance
  - speed enhancements to ORM object instantiation, eager loading of rows
  - invalid options sent to 'cascade' string will raise an exception
    [ticket:406]
  - fixed bug in mapper refresh/expire whereby eager loaders didnt properly
    re-populate item lists [ticket:407]
  - fix to post_update to ensure rows are updated even for non insert/delete
    scenarios [ticket:413]
  - added an error message if you actually try to modify primary key values on
    an entity and then flush it [ticket:412]
- extensions
  - added "validate=False" argument to assign_mapper, if True will insure that
    only mapped attributes are named [ticket:426]
  - assign_mapper gets "options", "instances" functions added (i.e.
    MyClass.instances())

0.3.3
- string-based FROM clauses fixed, i.e. select(..., from_obj=["sometext"])
- fixes to passive_deletes flag, lazy=None (noload) flag
- added example/docs for dealing with large collections
- added object_session() method to sqlalchemy namespace
- fixed QueuePool bug whereby its better able to reconnect to a database
that was not reachable (thanks to Sébastien Lelong), also fixed dispose()
method
- patch that makes MySQL rowcount work correctly! [ticket:396]
- fix to MySQL catch of 2006/2014 errors to properly re-raise OperationalError
exception

0.3.2
- major connection pool bug fixed.  fixes MySQL out of sync
errors, will also prevent transactions getting rolled back
accidentally in all DBs [ticket:387]
- major speed enhancements vs. 0.3.1, to bring speed
back to 0.2.8 levels 
  - made conditional dozens of debug log calls that were 
  time-intensive to generate log messages
  - fixed bug in cascade rules whereby the entire object graph
  could be unnecessarily cascaded on the save/update cascade
  - various speedups in attributes module
- identity map in Session is by default *no longer weak referencing*.
to have it be weak referencing, use create_session(weak_identity_map=True)
fixes [ticket:388]
- MySQL detects errors 2006 (server has gone away) and 2014
(commands out of sync) and invalidates the connection on which it occured.
- MySQL bool type fix: [ticket:307]
- postgres reflection fixes: [ticket:349] [ticket:382]
- added keywords for EXCEPT, INTERSECT, EXCEPT ALL, INTERSECT ALL
[ticket:247]
- assign_mapper in assignmapper extension returns the created mapper
[changeset:2110]
- added label() function to Select class, when scalar=True is used
to create a scalar subquery 
i.e. "select x, y, (select max(foo) from table) AS foomax from table"
- added onupdate and ondelete keyword arguments to ForeignKey; propigate
to underlying ForeignKeyConstraint if present.  (dont propigate in the
other direction, however)
- fix to session.update() to preserve "dirty" status of incoming object
- sending a selectable to an IN via the in_() function no longer creates 
a "union" out of multiple selects; only one selectable to a the in_() function
is allowed now (make a union yourself if union is needed)
- improved support for disabling save-update cascade via cascade="none" etc.
- added "remote_side" argument to relation(), used only with self-referential
mappers to force the direction of the parent/child relationship.  replaces
the usage of the "foreignkey" parameter for "switching" the direction.
"foreignkey" argument is deprecated for all uses and will eventually
be replaced by an argument dedicated to ForeignKey specification on mappers.

0.3.1
- Engine/Pool:
  - some new Pool utility classes, updated docs
  - "use_threadlocal" on Pool defaults to False (same as create_engine)
  - fixed direct execution of Compiled objects
  - create_engine() reworked to be strict about incoming **kwargs.  all keyword
arguments must be consumed by one of the dialect, connection pool, and engine
constructors, else a TypeError is thrown which describes the full set of
invalid kwargs in relation to the selected dialect/pool/engine configuration.
- Databases/Types:
  - MySQL catches exception on "describe" and reports as NoSuchTableError
  - further fixes to sqlite booleans, weren't working as defaults
  - fix to postgres sequence quoting when using schemas
- ORM:
  - the "delete" cascade will load in all child objects, if they were not
loaded already.  this can be turned off (i.e. the old behavior) by setting 
passive_deletes=True on a relation().
  - adjustments to reworked eager query generation to not fail on circular
eager-loaded relationships (like backrefs)
  - fixed bug where eagerload() (nor lazyload()) option didn't properly
instruct the Query whether or not to use "nesting" when producing a
LIMIT query.
  - fixed bug in circular dependency sorting at flush time; if object A
contained a cyclical many-to-one relationship to object B, and object B 
was just attached to object A, *but* object B itself wasnt changed,
the many-to-one synchronize of B's primary key attribute to A's foreign key
attribute wouldnt occur.  [ticket:360]
  - implemented from_obj argument for query.count, improves count function
on selectresults [ticket:325]
  - added an assertion within the "cascade" step of ORM relationships to check
that the class of object attached to a parent object is appropriate
(i.e. if A.items stores B objects, raise an error if a C is appended to A.items)
  - new extension sqlalchemy.ext.associationproxy, provides transparent 
"association object" mappings.  new example 
examples/association/proxied_association.py illustrates.
  - improvement to single table inheritance to load full hierarchies beneath 
the target class
  - fix to subtle condition in topological sort where a node could appear twice,
for [ticket:362]
  - additional rework to topological sort, refactoring, for [ticket:365]
  - "delete-orphan" for a certain type can be set on more than one parent class;
the instance is an "orphan" only if its not attached to *any* of those parents

0.3.0
- General:
    - logging is now implemented via standard python "logging" module.
    "echo" keyword parameters are still functional but set/unset
    log levels for their respective classes/instances.  all logging
    can be controlled directly through the Python API by setting
    INFO and DEBUG levels for loggers in the "sqlalchemy" namespace.
    class-level logging is under "sqlalchemy.<module>.<classname>",
    instance-level logging under "sqlalchemy.<module>.<classname>.0x..<00-FF>".
    Test suite includes "--log-info" and "--log-debug" arguments
    which work independently of --verbose/--quiet.  Logging added
    to orm to allow tracking of mapper configurations, row iteration.
    - the documentation-generation system has been overhauled to be
    much simpler in design and more integrated with Markdown
- Specific Databases:
    - SQLite:
    - sqlite boolean datatype converts False/True to 0/1 by default
    - fixes to Date/Time (SLDate/SLTime) types; works as good as postgres 
    now [ticket:335]
    - MS-SQL: 
    - fixes bug 261 (table reflection broken for MS-SQL case-sensitive 
    databases)
    - can now specify port for pymssql
    - introduces new "auto_identity_insert" option for auto-switching 
    between "SET IDENTITY_INSERT" mode when values specified for IDENTITY columns 
    - now supports multi-column foreign keys
    - fix to reflecting date/datetime columns
    - NCHAR and NVARCHAR type support added
    - Oracle:
    - Oracle has experimental support for cx_Oracle.TIMESTAMP, which requires
    a setinputsizes() call on the cursor that is now enabled via the
    'auto_setinputsizes' flag to the oracle dialect.  
    - Firebird:
    - aliases do not use "AS"
    - correctly raises NoSuchTableError when reflecting non-existent table
- Schema:
    - a fair amount of cleanup to the schema package, removal of ambiguous
    methods, methods that are no longer needed.  slightly more constrained
    useage, greater emphasis on explicitness
    - the "primary_key" attribute of Table and other selectables becomes
    a setlike ColumnCollection object; is ordered but not numerically
    indexed.  a comparison clause between two pks that are derived from the 
    same underlying tables (i.e. such as two Alias objects) can be generated 
    via table1.primary_key==table2.primary_key
    - ForeignKey(Constraint) supports "use_alter=True", to create/drop a foreign key
    via ALTER.  this allows circular foreign key relationships to be set up.
    - append_item() methods removed from Table and Column; preferably
    construct Table/Column/related objects inline, but if needed use 
    append_column(), append_foreign_key(), append_constraint(), etc.
    - table.create() no longer returns the Table object, instead has no
    return value.  the usual case is that tables are created via metadata,
    which is preferable since it will handle table dependencies.
    - added UniqueConstraint (goes at Table level), CheckConstraint
    (goes at Table or Column level).
    - index=False/unique=True on Column now creates a UniqueConstraint,
    index=True/unique=False creates a plain Index, 
    index=True/unique=True on Column creates a unique Index.  'index'
    and 'unique' keyword arguments to column are now boolean only; for
    explcit names and groupings of indexes or unique constraints, use the
    UniqueConstraint/Index constructs explicitly.
    - added autoincrement=True to Column; will disable schema generation
    of SERIAL/AUTO_INCREMENT/identity seq for postgres/mysql/mssql if
    explicitly set to False
    - TypeEngine objects now have methods to deal with copying and comparing
    values of their specific type.  Currently used by the ORM, see below.
    - fixed condition that occurred during reflection when a primary key
    column was explciitly overridden, where the PrimaryKeyConstraint would
    get both the reflected and the programmatic column doubled up
    - the "foreign_key" attribute on Column and ColumnElement in general
    is deprecated, in favor of the "foreign_keys" list/set-based attribute,
    which takes into account multiple foreign keys on one column. 
    "foreign_key" will return the first element in the "foreign_keys" list/set
    or None if the list is empty.
- Connections/Pooling/Execution:
    - connection pool tracks open cursors and automatically closes them
    if connection is returned to pool with cursors still opened.  Can be
    affected by options which cause it to raise an error instead, or to 
    do nothing.  fixes issues with MySQL, others
    - fixed bug where Connection wouldnt lose its Transaction
    after commit/rollback
    - added scalar() method to ComposedSQLEngine, ResultProxy
    - ResultProxy will close() the underlying cursor when the ResultProxy
    itself is closed.  this will auto-close cursors for ResultProxy objects
    that have had all their rows fetched (or had scalar() called).
    - ResultProxy.fetchall() internally uses DBAPI fetchall() for better efficiency,
    added to mapper iteration as well (courtesy Michael Twomey)
- SQL Construction:
    - changed "for_update" parameter to accept False/True/"nowait"
    and "read", the latter two of which are interpreted only by
    Oracle and Mysql [ticket:292]
    - added extract() function to sql dialect 
    (SELECT extract(field FROM expr))
    - BooleanExpression includes new "negate" argument to specify
    the appropriate negation operator if one is available.
    - calling a negation on an "IN" or "IS" clause will result in
    "NOT IN", "IS NOT" (as opposed to NOT (x IN y)). 
    - Function objects know what to do in a FROM clause now.  their
    behavior should be the same, except now you can also do things like
    select(['*'], from_obj=[func.my_function()]) to get multiple 
    columns from the result, or even use sql.column() constructs to name the 
    return columns [ticket:172]
- ORM:
    - attribute tracking modified to be more intelligent about detecting
    changes, particularly with mutable types.  TypeEngine objects now
    take a greater role in defining how to compare two scalar instances,
    including the addition of a MutableType mixin which is implemented by
    PickleType.  unit-of-work now tracks the "dirty" list as an expression
    of all persistent objects where the attribute manager detects changes.
    The basic issue thats fixed is detecting changes on PickleType 
    objects, but also generalizes type handling and "modified" object
    checking to be more complete and extensible.
    - a wide refactoring to "attribute loader" and "options" architectures.
    ColumnProperty and PropertyLoader define their loading behaivor via switchable
    "strategies", and MapperOptions no longer use mapper/property copying 
    in order to function; they are instead propigated via QueryContext
    and SelectionContext objects at query/instances time.
    All of the internal copying of mappers and properties that was used to handle
    inheritance as well as options() has been removed; the structure
    of mappers and properties is much simpler than before and is clearly laid out
    in the new 'interfaces' module.
    - related to the mapper/property overhaul, internal refactoring to 
    mapper instances() method to use a SelectionContext object to track 
    state during the operation.
    SLIGHT API BREAKAGE: the append_result() and populate_instances()
    methods on MapperExtension have a slightly different method signature
    now as a result of the change; hoping that these methods are not 
    in widespread use as of yet.
    - instances() method moved to Query now, backwards-compatible 
    version remains on Mapper.  
    - added contains_eager() MapperOption, used in conjunction with
    instances() to specify properties that should be eagerly loaded
    from the result set, using their plain column names by default, or translated
    given an custom row-translation function.
    - more rearrangements of unit-of-work commit scheme to better allow
    dependencies within circular flushes to work properly...updated
    task traversal/logging implementation
    - polymorphic mappers (i.e. using inheritance) now produces INSERT
    statements in order of tables across all inherited classes
    [ticket:321]
    - added an automatic "row switch" feature to mapping, which will
    detect a pending instance/deleted instance pair with the same 
    identity key and convert the INSERT/DELETE to a single UPDATE
    - "association" mappings simplified to take advantage of 
    automatic "row switch" feature
    - "custom list classes" is now implemented via the "collection_class"
    keyword argument to relation().  the old way still works but is
    deprecated [ticket:212]
    - added "viewonly" flag to relation(), allows construction of
    relations that have no effect on the flush() process.
    - added "lockmode" argument to base Query select/get functions, 
    including "with_lockmode" function to get a Query copy that has 
    a default locking mode.  Will translate "read"/"update" 
    arguments into a for_update argument on the select side.
    [ticket:292]
    - implemented "version check" logic in Query/Mapper, used
    when version_id_col is in effect and query.with_lockmode()
    is used to get() an instance thats already loaded
    - post_update behavior improved; does a better job at not 
    updating too many rows, updates only required columns
    [ticket:208]
    - adjustments to eager loading so that its "eager chain" is
    kept separate from the normal mapper setup, thereby
    preventing conflicts with lazy loader operation, fixes 
    [ticket:308]
    - fix to deferred group loading
    - session.flush() wont close a connection it opened [ticket:346]
    - added "batch=True" flag to mapper; if False, save_obj
    will fully save one object at a time including calls
    to before_XXXX and after_XXXX
    - added "column_prefix=None" argument to mapper; prepends the
    given string (typically '_') to column-based attributes automatically
    set up from the mapper's Table
    - specifying joins in the from_obj argument of query.select() will
    replace the main table of the query, if the table is somewhere within
    the given from_obj.  this makes it possible to produce custom joins and
    outerjoins in queries without the main table getting added twice.
    [ticket:315]
    - eagerloading is adjusted to more thoughtfully attach its LEFT OUTER JOINs
    to the given query, looking for custom "FROM" clauses that may have 
    already been set up.
    - added join_to and outerjoin_to transformative methods to SelectResults,
    to build up join/outerjoin conditions based on property names. also
    added select_from to explicitly set from_obj parameter.
    - removed "is_primary" flag from mapper.

0.2.8
- cleanup on connection methods + documentation.  custom DBAPI
arguments specified in query string, 'connect_args' argument
to 'create_engine', or custom creation function via 'creator'
function to 'create_engine'.
- added "recycle" argument to Pool, is "pool_recycle" on create_engine,
defaults to 3600 seconds; connections after this age will be closed and
replaced with a new one, to handle db's that automatically close 
stale connections [ticket:274]
- changed "invalidate" semantics with pooled connection; will 
instruct the underlying connection record to reconnect the next 
time its called.  "invalidate" will also automatically be called
if any error is thrown in the underlying call to connection.cursor().
this will hopefully allow the connection pool to reconnect to a
database that had been stopped and started without restarting
the connecting application [ticket:121] 
- eesh !  the tutorial doctest was broken for quite some time.
- add_property() method on mapper does a "compile all mappers"
step in case the given property references a non-compiled mapper
(as it did in the case of the tutorial !)
- [ticket:277] check for pg sequence already existing before create
- if a contextual session is established via MapperExtension.get_session
(as it is using the sessioncontext plugin, etc), a lazy load operation
will use that session by default if the parent object is not 
persistent with a session already.
- lazy loads will not fire off for an object that does not have a 
database identity (why?  
see http://www.sqlalchemy.org/trac/wiki/WhyDontForeignKeysLoadData)
- unit-of-work does a better check for "orphaned" objects that are
part of a "delete-orphan" cascade, for certain conditions where the 
parent isnt available to cascade from.
- mappers can tell if one of their objects is an "orphan" based
on interactions with the attribute package. this check is based
on a status flag maintained for each relationship 
when objects are attached and detached from each other.
- it is now invalid to declare a self-referential relationship with
"delete-orphan" (as the abovementioned check would make them impossible
to save)
- improved the check for objects being part of a session when the
unit of work seeks to flush() them as part of a relationship..
- [ticket:280] statement execution supports using the same BindParam
object more than once in an expression; simplified handling of positional
parameters.  nice job by Bill Noon figuring out the basic idea.
- postgres reflection moved to use pg_schema tables, can be overridden
with use_information_schema=True argument to create_engine
[ticket:60], [ticket:71]
- added case_sensitive argument to MetaData, Table, Column, determines
itself automatically based on if a parent schemaitem has a non-None
setting for the flag, or if not, then whether the identifier name is all lower
case or not.  when set to True, quoting is applied to identifiers with mixed or 
uppercase identifiers.  quoting is also applied automatically in all cases to 
identifiers that are known to be reserved words or contain other non-standard 
characters. various database dialects can override all of this behavior, but 
currently they are all using the default behavior.  tested with postgres, mysql, 
sqlite, oracle.  needs more testing with firebird, ms-sql. part of the ongoing 
work with [ticket:155]
- unit tests updated to run without any pysqlite installed; pool
test uses a mock DBAPI
- urls support escaped characters in passwords [ticket:281]
- added limit/offset to UNION queries (though not yet in oracle)
- added "timezone=True" flag to DateTime and Time types.  postgres
so far will convert this to "TIME[STAMP] (WITH|WITHOUT) TIME ZONE",
so that control over timezone presence is more controllable (psycopg2
returns datetimes with tzinfo's if available, which can create confusion
against datetimes that dont).
- fix to using query.count() with distinct, **kwargs with SelectResults
count() [ticket:287]
- deregister Table from MetaData when autoload fails; [ticket:289]
- import of py2.5s sqlite3 [ticket:293]
- unicode fix for startswith()/endswith() [ticket:296]

0.2.7
- quoting facilities set up so that database-specific quoting can be
turned on for individual table, schema, and column identifiers when
used in all queries/creates/drops.  Enabled via "quote=True" in 
Table or Column, as well as "quote_schema=True" in Table.  Thanks to
Aaron Spike for his excellent efforts.
- assignmapper was setting is_primary=True, causing all sorts of mayhem
by not raising an error when redundant mappers were set up, fixed
- added allow_null_pks option to Mapper, allows rows where some
primary key columns are null (i.e. when mapping to outer joins etc)
- modifcation to unitofwork to not maintain ordering within the
"new" list or within the UOWTask "objects" list; instead, new objects
are tagged with an ordering identifier as they are registered as new
with the session, and the INSERT statements are then sorted within the 
mapper save_obj.  the INSERT ordering has basically been pushed all
the way to the end of the flush cycle. that way the various sorts and 
organizations occuring within UOWTask (particularly the circular task 
sort) dont have to worry about maintaining order (which they werent anyway)
- fixed reflection of foreign keys to autoload the referenced table
if it was not loaded already
- [ticket:256] - pass URL query string arguments to connect() function
- [ticket:257] - oracle boolean type
- custom primary/secondary join conditions in a relation *will* be propigated
to backrefs by default.  specifying a backref() will override this behavior.
- better check for ambiguous join conditions in sql.Join; propigates to a
better error message in PropertyLoader (i.e. relation()/backref()) for when
the join condition can't be reasonably determined.
- sqlite creates ForeignKeyConstraint objects properly upon table 
reflection.
- adjustments to pool stemming from changes made for [ticket:224]. 
overflow counter should only be decremented if the connection actually
succeeded.  added a test script to attempt testing this.
- fixed mysql reflection of default values to be PassiveDefault
- added reflected 'tinyint', 'mediumint' type to MS-SQL [ticket:263], 
[ticket:264]
- SingletonThreadPool has a size and does a cleanup pass, so that 
only a given number of thread-local connections stay around (needed
for sqlite applications that dispose of threads en masse)
- fixed small pickle bug(s) with lazy loaders [ticket:265] [ticket:267]
- fixed possible error in mysql reflection where certain versions
return an array instead of string for SHOW CREATE TABLE call
- fix to lazy loads when mapping to joins [changeset:1770]
- all create()/drop() calls have a keyword argument of "connectable".
"engine" is deprecated.
- fixed ms-sql connect() to work with adodbapi
- added "nowait" flag to Select()
- inheritance check uses issubclass() instead of direct __mro__ check
to make sure class A inherits from B, allowing mapper inheritance to more 
flexibly correspond to class inheritance [ticket:271]
- SelectResults will use a subselect, when calling an aggregate (i.e.
max, min, etc.) on a SelectResults that has an ORDER BY clause
[ticket:252]
- fixes to types so that database-specific types more easily used;
fixes to mysql text types to work with this methodology
[ticket:269] 
- some fixes to sqlite date type organization
- added MSTinyInteger to MS-SQL [ticket:263]

0.2.6
- big overhaul to schema to allow truly composite primary and foreign
key constraints, via new ForeignKeyConstraint and PrimaryKeyConstraint
objects.
Existing methods of primary/foreign key creation have not been changed
but use these new objects behind the scenes.  table creation
and reflection is now more table oriented rather than column oriented.
[ticket:76]
- overhaul to MapperExtension calling scheme, wasnt working very well 
previously
- tweaks to ActiveMapper, supports self-referential relationships
- slight rearrangement to objectstore (in activemapper/threadlocal)
so that the SessionContext is referenced by '.context' instead
of subclassed directly.
- activemapper will use threadlocal's objectstore if the mod is
activated when activemapper is imported
- small fix to URL regexp to allow filenames with '@' in them
- fixes to Session expunge/update/etc...needs more cleanup.
- select_table mappers *still* werent always compiling
- fixed up Boolean datatype
- added count()/count_by() to list of methods proxied by assignmapper;
this also adds them to activemapper
- connection exceptions wrapped in DBAPIError
- ActiveMapper now supports autoloading column definitions from the
database if you supply a __autoload__ = True attribute in your
mapping inner-class.  Currently this does not support reflecting 
any relationships.
- deferred column load could screw up the connection status in 
a flush() under some circumstances, this was fixed
- expunge() was not working with cascade, fixed.
- potential endless loop in cascading operations fixed.
- added "synonym()" function, applied to properties to have a 
propname the same as another, for the purposes of overriding props
and allowing the original propname to be accessible in select_by().
- fix to typing in clause construction which specifically helps
type issues with polymorphic_union (CAST/ColumnClause propigates
its type to proxy columns)
- mapper compilation work ongoing, someday it'll work....moved 
around the initialization of MapperProperty objects to be after
all mappers are created to better handle circular compilations.
do_init() method is called on all properties now which are more 
aware of their "inherited" status if so.
- eager loads explicitly disallowed on self-referential relationships, or
relationships to an inheriting mapper (which is also self-referential)
- reduced bind param size in query._get to appease the picky oracle 
[ticket:244]
- added 'checkfirst' argument to table.create()/table.drop(), as 
well as table.exists() [ticket:234]
- some other ongoing fixes to inheritance [ticket:245]
- attribute/backref/orphan/history-tracking tweaks as usual...

0.2.5
- fixed endless loop bug in select_by(), if the traversal hit
two mappers that referenced each other
- upgraded all unittests to insert './lib/' into sys.path, 
working around new setuptools PYTHONPATH-killing behavior
- further fixes with attributes/dependencies/etc....
- improved error handling for when DynamicMetaData is not connected
- MS-SQL support largely working (tested with pymssql)
- ordering of UPDATE and DELETE statements within groups is now 
in order of primary key values, for more deterministic ordering
- after_insert/delete/update mapper extensions now called per object,
not per-object-per-table
- further fixes/refactorings to mapper compilation 

0.2.4
- try/except when the mapper sets init.__name__ on a mapped class,
supports python 2.3
- fixed bug where threadlocal engine would still autocommit
despite a transaction in progress
- lazy load and deferred load operations require the parent object
to be in a Session to do the operation; whereas before the operation
would just return a blank list or None, it now raises an exception.
- Session.update() is slightly more lenient if the session to which
the given object was formerly attached to was garbage collected;
otherwise still requires you explicitly remove the instance from 
the previous Session.
- fixes to mapper compilation, checking for more error conditions
- small fix to eager loading combined with ordering/limit/offset
- utterly remarkable:  added a single space between 'CREATE TABLE'
and '(<the rest of it>' since *thats how MySQL indicates a non-
reserved word tablename.....* [ticket:206]
- more fixes to inheritance, related to many-to-many relations
properly saving
- fixed bug when specifying explicit module to mysql dialect
- when QueuePool times out it raises a TimeoutError instead of
erroneously making another connection
- Queue.Queue usage in pool has been replaced with a locally
modified version (works in py2.3/2.4!) that uses a threading.RLock 
for a mutex.  this is to fix a reported case where a ConnectionFairy's 
__del__() method got called within the Queue's get() method, which 
then returns its connection to the Queue via the the put() method, 
causing a reentrant hang unless threading.RLock is used.
- postgres will not place SERIAL keyword on a primary key column
if it has a foreign key constraint
- cursor() method on ConnectionFairy allows db-specific extension
arguments to be propigated [ticket:221]
- lazy load bind params properly propigate column type [ticket:225]
- new MySQL types: MSEnum, MSTinyText, MSMediumText, MSLongText, etc.
more support for MS-specific length/precision params in numeric types
patch courtesy Mike Bernson
- some fixes to connection pool invalidate() [ticket:224]

0.2.3
- overhaul to mapper compilation to be deferred.  this allows mappers
to be constructed in any order, and their relationships to each
other are compiled when the mappers are first used.
- fixed a pretty big speed bottleneck in cascading behavior particularly
when backrefs were in use
- the attribute instrumentation module has been completely rewritten; its
now a large degree simpler and clearer, slightly faster.  the "history"
of an attribute is no longer micromanaged with each change and is
instead part of a "CommittedState" object created when the 
instance is first loaded.  HistoryArraySet is gone, the behavior of
list attributes is now more open ended (i.e. theyre not sets anymore).
- py2.4 "set" construct used internally, falls back to sets.Set when
"set" not available/ordering is needed.
- fix to transaction control, so that repeated rollback() calls 
dont fail (was failing pretty badly when flush() would raise 
an exception in a larger try/except transaction block)
- "foreignkey" argument to relation() can also be a list.  fixed
auto-foreignkey detection [ticket:151]
- fixed bug where tables with schema names werent getting indexed in
the MetaData object properly
- fixed bug where Column with redefined "key" property wasnt getting
type conversion happening in the ResultProxy [ticket:207]
- fixed 'port' attribute of URL to be an integer if present
- fixed old bug where if a many-to-many table mapped as "secondary"
had extra columns, delete operations didnt work
- bugfixes for mapping against UNION queries
- fixed incorrect exception class thrown when no DB driver present
- added NonExistentTable exception thrown when reflecting a table
that doesnt exist [ticket:138]
- small fix to ActiveMapper regarding one-to-one backrefs, other
refactorings
- overridden constructor in mapped classes gets __name__ and
__doc__ from the original class
- fixed small bug in selectresult.py regarding mapper extension
[ticket:200]
- small tweak to cascade_mappers, not very strongly supported 
function at the moment
- some fixes to between(), column.between() to propigate typing
information better [ticket:202]
- if an object fails to be constructed, is not added to the 
session [ticket:203]
- CAST function has been made into its own clause object with
its own compilation function in ansicompiler; allows MySQL
to silently ignore most CAST calls since MySQL
seems to only support the standard CAST syntax with Date types.  
MySQL-compatible CAST support for strings, ints, etc. a TODO

0.2.2
- big improvements to polymorphic inheritance behavior, enabling it
to work with adjacency list table structures [ticket:190]
- major fixes and refactorings to inheritance relationships overall,
more unit tests
- fixed "echo_pool" flag on create_engine()
- fix to docs, removed incorrect info that close() is unsafe to use
with threadlocal strategy (its totally safe !)
- create_engine() can take URLs as string or unicode [ticket:188]
- firebird support partially completed; 
thanks to James Ralston and Brad Clements for their efforts.
- Oracle url translation was broken, fixed, will feed host/port/sid
into cx_oracle makedsn() if 'database' field is present, else uses 
straight TNS name from the 'host' field
- fix to using unicode criterion for query.get()/query.load()
- count() function on selectables now uses table primary key or 
first column instead of "1" for criterion, also uses label "rowcount"
instead of "count".  
- got rudimental "mapping to multiple tables" functionality cleaned up, 
more correctly documented
- restored global_connect() function, attaches to a DynamicMetaData
instance called "default_metadata".  leaving MetaData arg to Table
out will use the default metadata.
- fixes to session cascade behavior, entity_name propigation
- reorganized unittests into subdirectories
- more fixes to threadlocal connection nesting patterns

0.2.1
- "pool" argument to create_engine() properly propigates
- fixes to URL, raises exception if not parsed, does not pass blank
fields along to the DB connect string (a string such as 
user:host@/db was breaking on postgres)
- small fixes to Mapper when it inserts and tries to get
new primary key values back
- rewrote half of TLEngine, the ComposedSQLEngine used with 
'strategy="threadlocal"'.  it now properly implements engine.begin()/
engine.commit(), which nest fully with connection.begin()/trans.commit().
added about six unittests.
- major "duh" in pool.Pool, forgot to put back the WeakValueDictionary.
unittest which was supposed to check for this was also silently missing
it.  fixed unittest to ensure that ConnectionFairy properly falls out
of scope.
- placeholder dispose() method added to SingletonThreadPool, doesnt 
do anything yet
- rollback() is automatically called when an exception is raised,
but only if theres no transaction in process (i.e. works more like
autocommit).
- fixed exception raise in sqlite if no sqlite module present
- added extra example detail for association object doc
- Connection adds checks for already being closed

0.2.0
- overhaul to Engine system so that what was formerly the SQLEngine
is now a ComposedSQLEngine which consists of a variety of components,
including a Dialect, ConnectionProvider, etc. This impacted all the
db modules as well as Session and Mapper.
- create_engine now takes only RFC-1738-style strings:
driver://user:password@host:port/database
- total rewrite of connection-scoping methodology, Connection objects
can now execute clause elements directly, added explicit "close" as
well as support throughout Engine/ORM to handle closing properly,
no longer relying upon __del__ internally to return connections 
to the pool [ticket:152].
- overhaul to Session interface and scoping.  uses hibernate-style
methods, including query(class), save(), save_or_update(), etc.
no threadlocal scope is installed by default.  Provides a binding
interface to specific Engines and/or Connections so that underlying
Schema objects do not need to be bound to an Engine.  Added a basic
SessionTransaction object that can simplistically aggregate transactions 
across multiple engines.
- overhaul to mapper's dependency and "cascade" behavior; dependency logic
factored out of properties.py into a separate module "dependency.py".
"cascade" behavior is now explicitly controllable, proper implementation 
of "delete", "delete-orphan", etc.  dependency system can now determine at 
flush time if a child object has a parent or not so that it makes better 
decisions on how that child should be updated in the DB with regards to deletes.
- overhaul to Schema to build upon MetaData object instead of an Engine.
Entire SQL/Schema system can be used with no Engines whatsoever, executed
solely by an explicit Connection object.  the "bound" methodlogy exists via the 
BoundMetaData for schema objects.  ProxyEngine is generally not needed
anymore and is replaced by DynamicMetaData.
- true polymorphic behavior implemented, fixes [ticket:167]
- "oid" system has been totally moved into compile-time behavior; 
if they are used in an order_by where they are not available, the order_by
doesnt get compiled, fixes [ticket:147]
- overhaul to packaging; "mapping" is now "orm", "objectstore" is now
"session", the old "objectstore" namespace gets loaded in via the
"threadlocal" mod if used
- mods now called in via "import <modname>".  extensions favored over
mods as mods are globally-monkeypatching
- fix to add_property so that it propigates properties to inheriting 
mappers [ticket:154]
- backrefs create themselves against primary mapper of its originating
property, priamry/secondary join arguments can be specified to override.
helps their usage with polymorphic mappers
- "table exists" function has been implemented [ticket:31]
- "create_all/drop_all" added to MetaData object [ticket:98]
- improvements and fixes to topological sort algorithm, as well as more
unit tests
- tutorial page added to docs which also can be run with a custom doctest
runner to ensure its properly working.  docs generally overhauled to 
deal with new code patterns
- many more fixes, refactorings.
- migration guide is available on the Wiki at 
http://www.sqlalchemy.org/trac/wiki/02Migration

0.1.7
- some fixes to topological sort algorithm
- added DISTINCT ON support to Postgres (just supply distinct=[col1,col2..])
- added __mod__ (% operator) to sql expressions
- "order_by" mapper property inherited from inheriting mapper
- fix to column type used when mapper UPDATES/DELETEs
- with convert_unicode=True, reflection was failing, has been fixed
- types types types!  still werent working....have to use TypeDecorator again :(
- mysql binary type converts array output to buffer, fixes PickleType
- fixed the attributes.py memory leak once and for all
- unittests are qualified based on the databases that support each one
- fixed bug where column defaults would clobber VALUES clause of insert objects
- fixed bug where table def w/ schema name would force engine connection
- fix for parenthesis to work correctly with subqueries in INSERT/UPDATE
- HistoryArraySet gets extend() method
- fixed lazyload support for other comparison operators besides =
- lazyload fix where two comparisons in the join condition point to the 
samem column
- added "construct_new" flag to mapper, will use __new__ to create instances
instead of __init__ (standard in 0.2)
- added selectresults.py to SVN, missed it last time
- tweak to allow a many-to-many relationship from a table to itself via
an association table
- small fix to "translate_row" function used by polymorphic example
- create_engine uses cgi.parse_qsl to read query string (out the window in 0.2)
- tweaks to CAST operator
- fixed function names LOCAL_TIME/LOCAL_TIMESTAMP -> LOCALTIME/LOCALTIMESTAMP
- fixed order of ORDER BY/HAVING in compile

0.1.6
- support for MS-SQL added courtesy Rick Morrison, Runar Petursson
- the latest SQLSoup from J. Ellis
- ActiveMapper has preliminary support for inheritance (Jeff Watkins)
- added a "mods" system which allows pluggable modules that modify/augment
core functionality, using the function "install_mods(*modnames)".
- added the first "mod", SelectResults, which modifies mapper selects to
return generators that turn ranges into LIMIT/OFFSET queries (Jonas Borgstr?- factored out querying capabilities of Mapper into a separate Query object
which is Session-centric.  this improves the performance of mapper.using(session)
and makes other things possible.
- objectstore/Session refactored, the official way to save objects is now 
via the flush() method.  The begin/commit functionality of Session is factored
into LegacySession which is still established as the default behavior, until
the 0.2 series.
- types system is bound to an engine at query compile time, not schema
construction time.  this simplifies the types system as well as the ProxyEngine.
- added 'version_id' keyword argument to mapper. this keyword should reference a
Column object with type Integer, preferably non-nullable, which will be used on
the mapped table to track version numbers. this number is incremented on each
save operation and is specifed in the UPDATE/DELETE conditions so that it
factors into the returned row count, which results in a ConcurrencyError if the
value received is not the expected count.
- added 'entity_name' keyword argument to mapper. a mapper is now associated
with a class via the class object as well as an optional entity_name parameter,
which is a string defaulting to None. any number of primary mappers can be
created for a class, qualified by the entity name. instances of those classes
will issue all of their load and save operations through their
entity_name-qualified mapper, and maintain separate a identity in the identity
map for an otherwise equilvalent object.
- overhaul to the attributes system. code has been clarified, and also fixed to
support proper polymorphic behavior on object attributes.
- added "for_update" flag to Select objects
- some fixes for backrefs
- fix for postgres1 DateTime type
- documentation pages mostly switched over to Markdown syntax

0.1.5
- added SQLSession concept to SQLEngine. this object keeps track of retrieving a
connection from the connection pool as well as an in-progress transaction.
methods push_session() and pop_session() added to SQLEngine which push/pop a new
SQLSession onto the engine, allowing operation upon a second connection "nested"
within the previous one, allowing nested transactions. Other tricks are sure to
come later regarding SQLSession.
- added nest_on argument to objectstore.Session. This is a single SQLEngine or
list of engines for which push_session()/pop_session() will be called each time
this Session becomes the active session (via objectstore.push_session() or
equivalent). This allows a unit of work Session to take advantage of the nested
transaction feature without explicitly calling push_session/pop_session on the
engine.
- factored apart objectstore/unitofwork to separate "Session scoping" from
"uow commit heavy lifting"
- added populate_instance() method to MapperExtension. allows an extension to
modify the population of object attributes. this method can call the
populate_instance() method on another mapper to proxy the attribute population
from one mapper to another; some row translation logic is also built in to help
with this.
- fixed Oracle8-compatibility "use_ansi" flag which converts JOINs to 
comparisons with the = and (+) operators, passes basic unittests
- tweaks to Oracle LIMIT/OFFSET support
- Oracle reflection uses ALL_** views instead of USER_** to get larger
list of stuff to reflect from
- fixes to Oracle foreign key reflection [ticket:105]
- objectstore.commit(obj1, obj2,...) adds an extra step to seek out private
relations on properties and delete child objects, even though its not a global
commit
- lots and lots of fixes to mappers which use inheritance, strengthened the 
concept of relations on a mapper being made towards the "local" table for that
mapper, not the tables it inherits.  allows more complex compositional patterns
to work with lazy/eager loading.
- added support for mappers to inherit from others based on the same table, 
just specify the same table as that of both parent/child mapper.
- some minor speed improvements to the attributes system with regards to 
instantiating and populating new objects. 
- fixed MySQL binary unit test
- INSERTs can receive clause elements as VALUES arguments, not just literal
values
- support for calling multi-tokened functions, i.e. schema.mypkg.func()
- added J. Ellis' SQLSoup module to extensions package
- added "polymorphic" examples illustrating methods to load multiple object types
from one mapper, the second of which uses the new populate_instance() method.
small improvements to mapper, UNION construct to help the examples along
- improvements/fixes to session.refresh()/session.expire() (which may have
been called "invalidate" earlier..)
- added session.expunge() which totally removes an object from the current
session
- added *args, **kwargs pass-thru to engine.transaction(func) allowing easier
creation of transactionalizing decorator functions
- added iterator interface to ResultProxy:  "for row in result:..."
- added assertion to tx = session.begin(); tx.rollback(); tx.begin(), i.e. cant
use it after a rollback()
- added date conversion on bind parameter fix to SQLite enabling dates to
work with pysqlite1
- improvements to subqueries to more intelligently construct their FROM
clauses [ticket:116]
- added PickleType to types.
- fixed two bugs with column labels with regards to bind parameters: bind param
keynames they are now generated from a column "label" in all relevant cases to
take advantage of excess-name-length rules, and checks for a peculiar collision
against a column named the same as "tablename_colname" added
- major overhaul to unit of work documentation, other documentation sections.
- fixed attributes bug where if an object is committed, its lazy-loaded list got 
blown away if it hadnt been loaded
- added unique_connection() method to engine, connection pool to return a
connection that is not part of the thread-local context or any current
transaction
- added invalidate() function to pooled connection.  will remove the connection
from the pool.  still need work for engines to auto-reconnect to a stale DB
though.
- added distinct() function to column elements so you can do
func.count(mycol.distinct())
- added "always_refresh" flag to Mapper, creates a mapper that will always
refresh the attributes of objects it gets/selects from the DB, overwriting any
changes made.

0.1.4
- create_engine() now uses genericized parameters; host/hostname,
db/dbname/database, password/passwd, etc. for all engine connections. makes
 engine URIs much more "universal"
- added support for SELECT statements embedded into a column clause, using the
flag "scalar=True"
- another overhaul to EagerLoading when used in conjunction with mappers that
inherit; improvements to eager loads figuring out their aliased queries
correctly, also relations set up against a mapper with inherited mappers will
create joins against the table that is specific to the mapper itself (i.e. and
not any tables that are inherited/are further down the inheritance chain),
this can be overridden by using custom primary/secondary joins.
- added J.Ellis patch to mapper.py so that selectone() throws an exception 
if query returns more than one object row, selectfirst() to not throw the 
exception. also adds selectfirst_by (synonymous with get_by) and selectone_by
- added onupdate parameter to Column, will exec SQL/python upon an update
statement.Also adds "for_update=True" to all DefaultGenerator subclasses
- added support for Oracle table reflection contributed by Andrija Zaric; 
still some bugs to work out regarding composite primary keys/dictionary selection
- checked in an initial Firebird module, awaiting testing.
- added sql.ClauseParameters dictionary object as the result for 
compiled.get_params(), does late-typeprocessing of bind parameters so 
that the original values are easier to access
- more docs for indexes, column defaults, connection pooling, engine construction
- overhaul to the construction of the types system. uses a simpler inheritance
pattern so that any of the generic types can be easily subclassed, with no need
for TypeDecorator.
- added "convert_unicode=False" parameter to SQLEngine, will cause all String
types to perform unicode encoding/decoding (makes Strings act like Unicodes)
- added 'encoding="utf8"' parameter to engine.  the given encoding will be 
used for all encode/decode calls within Unicode types as well as Strings 
when convert_unicode=True.
- improved support for mapping against UNIONs, added polymorph.py example
to illustrate multi-class mapping against a UNION
- fix to SQLite LIMIT/OFFSET syntax
- fix to Oracle LIMIT syntax
- added backref() function, allows backreferences to have keyword arguments
that will be passed to the backref.
- Sequences and ColumnDefault objects can do execute()/scalar() standalone
- SQL functions (i.e. func.foo()) can do execute()/scalar() standalone
- fix to SQL functions so that the ANSI-standard functions, i.e. current_timestamp
etc., do not specify parenthesis.  all other functions do.
- added settattr_clean and append_clean to SmartProperty, which set 
attributes without triggering a "dirty" event or any history. used as:
myclass.prop1.setattr_clean(myobject, 'hi')
- improved support to column defaults when used by mappers; mappers will pull
pre-executed defaults from statement's executed bind parameters
(pre-conversion) to populate them into a saved object's attributes; if any
PassiveDefaults have fired off, will instead post-fetch the row from the DB to
populate the object.
- added 'get_session().invalidate(*obj)' method to objectstore, instances will
refresh() themselves upon the next attribute access.
- improvements to SQL func calls including an "engine" keyword argument so
they can be execute()d or scalar()ed standalone, also added func accessor to
SQLEngine
- fix to MySQL4 custom table engines, i.e. TYPE instead of ENGINE
- slightly enhanced logging, includes timestamps and a somewhat configurable
formatting system, in lieu of a full-blown logging system
- improvements to the ActiveMapper class from the TG gang, including
many-to-many relationships
- added Double and TinyInt support to mysql

0.1.3
- completed "post_update" feature, will add a second update statement before
inserts and after deletes in order to reconcile a relationship without any
dependencies being created; used when persisting two rows that are dependent
on each other
- completed mapper.using(session) function, localized per-object Session
functionality; objects can be declared and manipulated as local to any
user-defined Session
- fix to Oracle "row_number over" clause with multiple tables
- mapper.get() was not selecting multiple-keyed objects if the mapper's table was a join,
such as in an inheritance relationship, this is fixed.
- overhaul to sql/schema packages so that the sql package can run all on its own,
producing selects, inserts, etc. without any engine dependencies.  builds upon
new TableClause/ColumnClause lexical objects.  Schema's Table/Column objects
are the "physical" subclasses of them.  simplifies schema/sql relationship,
extensions (like proxyengine), and speeds overall performance by a large margin. 
removes the entire getattr() behavior that plagued 0.1.1.
- refactoring of how the mapper "synchronizes" data between two objects into a
separate module, works better with properties attached to a mapper that has an 
additional inheritance relationship to one of the related tables, also the same
methodology used to synchronize parent/child objects now used by mapper to
synchronize between inherited and inheriting mappers.
- made objectstore "check for out-of-identitymap" more aggressive, will perform the
check when object attributes are modified or the object is deleted
- Index object fully implemented, can be constructed standalone, or via
"index" and "unique" arguments on Columns.
- added "convert_unicode" flag to SQLEngine, will treat all String/CHAR types
as Unicode types, with raw-byte/utf-8 translation on the bind parameter and 
result set side.
- postgres maintains a list of ANSI functions that must have no parenthesis so
function calls with no arguments work consistently
- tables can be created with no engine specified.  this will default their engine
to a module-scoped "default engine" which is a ProxyEngine.  this engine can 
be connected via the function "global_connect".
- added "refresh(*obj)" method to objectstore / Session to reload the attributes of
any set of objects from the database unconditionally

0.1.2
- fixed a recursive call in schema that was somehow running 994 times then returning
normally.  broke nothing, slowed down everything.  thanks to jpellerin for finding this.

0.1.1
- small fix to Function class so that expressions with a func.foo() use the type of the
Function object (i.e. the left side) as the type of the boolean expression, not the 
other side which is more of a moving target (changeset 1020).
- creating self-referring mappers with backrefs slightly easier (but still not that easy -
changeset 1019)
- fixes to one-to-one mappings (changeset 1015)
- psycopg1 date/time issue with None fixed (changeset 1005)
- two issues related to postgres, which doesnt want to give you the "lastrowid"
since oids are deprecated:
   * postgres database-side defaults that are on primary key cols *do* execute 
explicitly beforehand, even though thats not the idea of a PassiveDefault.  this is
because sequences on columns get reflected as PassiveDefaults, but need to be explicitly
executed on a primary key col so we know what we just inserted.  
   * if you did add a row that has a bunch of database-side defaults on it, 
and the PassiveDefault thing was working the old way, i.e. they just execute on 
the DB side, the "cant get the row back without an OID" exception that occurred
also will not happen unless someone (usually the ORM) explicitly asks for it.
- fixed a glitch with engine.execute_compiled where it was making a second 
ResultProxy that just got thrown away.
- began to implement newer logic in object properities.  you can now say
myclass.attr.property, which will give you the PropertyLoader corresponding to that
attribute, i.e. myclass.mapper.props['attr']
- eager loading has been internally overhauled to use aliases at all times.  more 
complicated chains of eager loads can now be created without any need for explicit
"use aliases"-type instructions.  EagerLoader code is also much simpler now.
- a new somewhat experimental flag "use_update" added to relations, indicates that 
this relationship should be handled by a second UPDATE statement, either after a 
primary INSERT or before a primary DELETE.  handles circular row dependencies.
- added exceptions module, all raised exceptions (except for some 
KeyError/AttributeError exceptions) descend from these classes.
- fix to date types with MySQL, returned timedelta converted to datetime.time
- two-phase objectstore.commit operations (i.e. begin/commit) now return a 
transactional object (SessionTrans), to more clearly indicate transaction boundaries.
- Index object with create/drop support added to schema
- fix to postgres, where it will explicitly pre-execute a PassiveDefault on a table
if it is a primary key column, pursuant to the ongoing "we cant get inserted rows 
back from postgres" issue
- change to information_schema query that gets back postgres table defs, now
uses explicit JOIN keyword, since one user had faster performance with 8.1
- fix to engine.process_defaults so it works correctly with a table that has 
different column name/column keys (changset 982)
- a column can only be attached to one table - this is now asserted
- postgres time types descend from Time type
- fix to alltests so that it runs types test (now named testtypes)
- fix to Join object so that it correctly exports its foreign keys (cs 973)
- creating relationships against mappers that use inheritance fixed (cs 973)

0.1.0
initial release
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