From b9d231869d7e39decabdec12478e359c4dcb95ee Mon Sep 17 00:00:00 2001
From: zeeeeeb <5767468+zeeeeeb@users.noreply.github.com>
Date: Sat, 12 Feb 2022 14:00:02 -0500
Subject: Implement generic Double and related fixed types

Added :class:`.Double`, :class:`.DOUBLE`, :class:`.DOUBLE_PRECISION`
datatypes to the base ``sqlalchemy.`` module namespace, for explicit use of
double/double precision as well as generic "double" datatypes. Use
:class:`.Double` for generic support that will resolve to DOUBLE/DOUBLE
PRECISION/FLOAT as needed for different backends.

Implemented DDL and reflection support for ``FLOAT`` datatypes which
include an explicit "binary_precision" value. Using the Oracle-specific
:class:`_oracle.FLOAT` datatype, the new parameter
:paramref:`_oracle.FLOAT.binary_precision` may be specified which will
render Oracle's precision for floating point types directly. This value is
interpreted during reflection. Upon reflecting back a ``FLOAT`` datatype,
the datatype returned is one of :class:`_types.DOUBLE_PRECISION` for a
``FLOAT`` for a precision of 126 (this is also Oracle's default precision
for ``FLOAT``), :class:`_types.REAL` for a precision of 63, and
:class:`_oracle.FLOAT` for a custom precision, as per Oracle documentation.

As part of this change, the generic :paramref:`_sqltypes.Float.precision`
value is explicitly rejected when generating DDL for Oracle, as this
precision cannot be accurately converted to "binary precision"; instead, an
error message encourages the use of
:meth:`_sqltypes.TypeEngine.with_variant` so that Oracle's specific form of
precision may be chosen exactly. This is a backwards-incompatible change in
behavior, as the previous "precision" value was silently ignored for
Oracle.

Fixes: #5465
Closes: #7674
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/7674
Pull-request-sha: 5c68419e5aee2e27bf21a8ac9eb5950d196c77e5

Change-Id: I831f4af3ee3b23fde02e8f6393c83e23dd7cd34d
---
 lib/sqlalchemy/dialects/sqlite/base.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'lib/sqlalchemy/dialects/sqlite/base.py')

diff --git a/lib/sqlalchemy/dialects/sqlite/base.py b/lib/sqlalchemy/dialects/sqlite/base.py
index 385de373e..79068c75f 100644
--- a/lib/sqlalchemy/dialects/sqlite/base.py
+++ b/lib/sqlalchemy/dialects/sqlite/base.py
@@ -1179,7 +1179,7 @@ ischema_names = {
     "DATE_CHAR": sqltypes.DATE,
     "DATETIME": sqltypes.DATETIME,
     "DATETIME_CHAR": sqltypes.DATETIME,
-    "DOUBLE": sqltypes.FLOAT,
+    "DOUBLE": sqltypes.DOUBLE,
     "DECIMAL": sqltypes.DECIMAL,
     "FLOAT": sqltypes.FLOAT,
     "INT": sqltypes.INTEGER,
-- 
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