- generalized the "freetds" / "unicode statements" behavior of MS-SQL/pyodbc
into the base Pyodbc connector, as this seems to apply to Sybase as well.
- generalized the python-sybase "use autocommit for DDL" into the pyodbc
connector. With pyodbc, the "autocommit" flag on connection is used,
as Pyodbc seems to have more database conversation than python-sybase that
can't otherwise be suppressed.
- Some platforms will now interpret certain literal values
as non-bind parameters, rendered literally into the SQL
statement. This to support strict SQL-92 rules that are
enforced by some platforms including MS-SQL and Sybase.
In this model, bind parameters aren't allowed in the
columns clause of a SELECT, nor are certain ambiguous
expressions like "?=?". When this mode is enabled, the base
compiler will render the binds as inline literals, but only across
strings and numeric values. Other types such as dates
will raise an error, unless the dialect subclass defines
a literal rendering function for those. The bind parameter
must have an embedded literal value already or an error
is raised (i.e. won't work with straight bindparam('x')).
Dialects can also expand upon the areas where binds are not
accepted, such as within argument lists of functions
(which don't work on MS-SQL when native SQL binding is used).
changes to Enum/SchemaType to re-support adaptation of string types.
This approach can be adapted by "conditional" unicode returning dialects
(i.e. pyodbc and possibly mxodbc) to remove the overhead
of isinstance(value, unicode) calls when the dialect returned type is
of dbapi.UNICODE, dbapi.NVARCHAR, etc.
info from the cursor before commit() is called on the
DBAPI connection in an "autocommit" scenario. This helps
mxodbc with rowcount and is probably a good idea overall.
- cx_oracle wants list(), not tuple(), for empty execute.
- cleaned up plain SQL param handling
upon close() - fixed that.
- Transaction object doesn't rollback or commit if it isn't
"active", allows more accurate nesting of begin/rollback/commit.
- Added basic support for mxODBC [ticket:1710].
- Python unicode objects as binds result in the Unicode type,
not string, thus eliminating a certain class of unicode errors
on drivers that don't support unicode binds.
a warning in all cases where it is asked to encode a non-unicode
Python string, and will do nothing for DBAPIs that already
accept Python unicode objects.
cx_oracle. An error will be raised if no cx_oracle
type can be found.
- Column() requires a type if it has no foreign keys (this is
not new). An error is now raised if a Column() has no type
and no foreign keys. [ticket:1705]
Behaves like the 'errors' keyword argument to
the standard library's string.decode() functions. This flag
requires that `convert_unicode` is set to `"force"` - otherwise,
SQLAlchemy is not guaranteed to handle the task of unicode
conversion. Note that this flag adds significant performance
overhead to row-fetching operations for backends that already
return unicode objects natively (which most DBAPIs do). This
flag should only be used as an absolute last resort for reading
strings from a column with varied or corrupted encodings,
which only applies to databases that accept invalid encodings
in the first place (i.e. MySQL. *not* PG, Sqlite, etc.)
- SchemaType and subclasses Boolean, Enum are now serializable,
including their ddl listener and other event callables.
[ticket:1694] [ticket:1698]
- AddConstraint/DropConstraint use the wrapper for _create_rule
- added test coverage for AddConstraint override of _create_rule
defined bind parameter name that directly conflicts with
a column-named bind generated directly from the SET or
VALUES clause of an update/insert generates a compile error.
This reduces call counts and eliminates some cases where
undesirable name conflicts could still occur.
reimplementing the highest impact functions.
The actual speedups will depend heavily on your DBAPI and
the mix of datatypes used in your tables, and can vary from
a 50% improvement to more than 200%. It also provides a modest
(~20%) indirect improvement to ORM speed for large queries.
Note that it is *not* built/installed by default.
See README for installation instructions.
- The most common result processors conversion function were
moved to the new "processors" module. Dialect authors are
encouraged to use those functions whenever they correspond
to their needs instead of implementing custom ones.
API, used for any expression construct that can be sent to
execute(). FunctionElement now inherits Executable so that
it gains execution_options(), which are also propagated
to the select() that's generated within execute().
Executable in turn subclasses _Generative which marks
any ClauseElement that supports the @_generative
decorator - these may also become "public" for the benefit
of the compiler extension at some point.
of determining the return type from an expression
as well as the adaptation of the Python operator into
a SQL operator, based on the full left/right/operator
of the given expression. In particular
the date/time/interval system created for Postgresql
EXTRACT in [ticket:1647] has now been generalized into
the type system. The previous behavior which often
occured of an expression "column + literal" forcing
the type of "literal" to be the same as that of "column"
will now usually not occur - the type of
"literal" is first derived from the Python type of the
literal, assuming standard native Python types + date
types, before falling back to that of the known type
on the other side of the expression. Also part
of [ticket:1683].
same way any func.foo() construct is, with automatic
SELECT being applied when passed to execute().
- The "type" and "bind" keyword arguments of a func.foo()
construct are now local to "func." constructs and are
not part of the FunctionElement base class, allowing
a "type" to be handled in a custom constructor or
class-level variable.
Mike Bayer