diff options
Diffstat (limited to 'lib/sqlalchemy/dialects/mssql/base.py')
| -rw-r--r-- | lib/sqlalchemy/dialects/mssql/base.py | 104 |
1 files changed, 37 insertions, 67 deletions
diff --git a/lib/sqlalchemy/dialects/mssql/base.py b/lib/sqlalchemy/dialects/mssql/base.py index 6670a28bd..e4f9ac3de 100644 --- a/lib/sqlalchemy/dialects/mssql/base.py +++ b/lib/sqlalchemy/dialects/mssql/base.py @@ -166,56 +166,6 @@ how SQLAlchemy handles this: This is an auxilliary use case suitable for testing and bulk insert scenarios. -.. _legacy_schema_rendering: - -Rendering of SQL statements that include schema qualifiers ---------------------------------------------------------- - -When using :class:`.Table` metadata that includes a "schema" qualifier, -such as:: - - account_table = Table( - 'account', metadata, - Column('id', Integer, primary_key=True), - Column('info', String(100)), - schema="customer_schema" - ) - -The SQL Server dialect has a long-standing behavior that it will attempt -to turn a schema-qualified table name into an alias, such as:: - - >>> eng = create_engine("mssql+pymssql://mydsn") - >>> print(account_table.select().compile(eng)) - SELECT account_1.id, account_1.info - FROM customer_schema.account AS account_1 - -This behavior is legacy, does not function correctly for many forms -of SQL statements, and will be disabled by default in the 1.1 series -of SQLAlchemy. As of 1.0.5, the above statement will produce the following -warning:: - - SAWarning: legacy_schema_aliasing flag is defaulted to True; - some schema-qualified queries may not function correctly. - Consider setting this flag to False for modern SQL Server versions; - this flag will default to False in version 1.1 - -This warning encourages the :class:`.Engine` to be created as follows:: - - >>> eng = create_engine("mssql+pymssql://mydsn", legacy_schema_aliasing=False) - -Where the above SELECT statement will produce:: - - >>> print(account_table.select().compile(eng)) - SELECT customer_schema.account.id, customer_schema.account.info - FROM customer_schema.account - -The warning will not emit if the ``legacy_schema_aliasing`` flag is set -to either True or False. - -.. versionadded:: 1.0.5 - Added the ``legacy_schema_aliasing`` flag to disable - the SQL Server dialect's legacy behavior with schema-qualified table - names. This flag will default to False in version 1.1. - Collation Support ----------------- @@ -322,6 +272,41 @@ behavior of this flag is as follows: .. versionadded:: 1.0.0 +.. _legacy_schema_rendering: + +Legacy Schema Mode +------------------ + +Very old versions of the MSSQL dialect introduced the behavior such that a +schema-qualified table would be auto-aliased when used in a +SELECT statement; given a table:: + + account_table = Table( + 'account', metadata, + Column('id', Integer, primary_key=True), + Column('info', String(100)), + schema="customer_schema" + ) + +this legacy mode of rendering would assume that "customer_schema.account" +would not be accepted by all parts of the SQL statement, as illustrated +below:: + + >>> eng = create_engine("mssql+pymssql://mydsn", legacy_schema_aliasing=True) + >>> print(account_table.select().compile(eng)) + SELECT account_1.id, account_1.info + FROM customer_schema.account AS account_1 + +This mode of behavior is now off by default, as it appears to have served +no purpose; however in the case that legacy applications rely upon it, +it is available using the ``legacy_schema_aliasing`` argument to +:func:`.create_engine` as illustrated above. + +.. versionchanged:: 1.1 the ``legacy_schema_aliasing`` flag introduced + in version 1.0.5 to allow disabling of legacy mode for schemas now + defaults to False. + + .. _mssql_indexes: Clustered Index Support @@ -1156,15 +1141,6 @@ class MSSQLCompiler(compiler.SQLCompiler): def _schema_aliased_table(self, table): if getattr(table, 'schema', None) is not None: - if self.dialect._warn_schema_aliasing and \ - table.schema.lower() != 'information_schema': - util.warn( - "legacy_schema_aliasing flag is defaulted to True; " - "some schema-qualified queries may not function " - "correctly. Consider setting this flag to False for " - "modern SQL Server versions; this flag will default to " - "False in version 1.1") - if table not in self.tablealiases: self.tablealiases[table] = table.alias() return self.tablealiases[table] @@ -1530,7 +1506,7 @@ class MSDialect(default.DefaultDialect): max_identifier_length=None, schema_name="dbo", deprecate_large_types=None, - legacy_schema_aliasing=None, **opts): + legacy_schema_aliasing=False, **opts): self.query_timeout = int(query_timeout or 0) self.schema_name = schema_name @@ -1538,13 +1514,7 @@ class MSDialect(default.DefaultDialect): self.max_identifier_length = int(max_identifier_length or 0) or \ self.max_identifier_length self.deprecate_large_types = deprecate_large_types - - if legacy_schema_aliasing is None: - self.legacy_schema_aliasing = True - self._warn_schema_aliasing = True - else: - self.legacy_schema_aliasing = legacy_schema_aliasing - self._warn_schema_aliasing = False + self.legacy_schema_aliasing = legacy_schema_aliasing super(MSDialect, self).__init__(**opts) |