Oracle default arraysize is now set by the driver

Changed the default arraysize of the Oracle dialects so that the value set
by the driver is used, that is 100 at the time of writing for both
cx_oracle and oracledb. Previously the value was set to 50 by default.

Fixes: #10877
Change-Id: Ie4c53f42437d3d7dbbad36398d7883472577f367
(cherry picked from commit c8214ad4389284dc9508e49aeca701e5bf164454)

diff --git a/doc/build/changelog/unreleased_20/10877.rst b/doc/build/changelog/unreleased_20/10877.rst
new file mode 100644 (file)
index 0000000..8aaac98
--- /dev/null
+++ b/doc/build/changelog/unreleased_20/10877.rst
@@ -0,0 +1,7 @@
+.. change::
+    :tags: oracle
+    :tickets: 10877
+
+    Changed the default arraysize of the Oracle dialects so that the value set
+    by the driver is used, that is 100 at the time of writing for both
+    cx_oracle and oracledb. Previously the value was set to 50 by default.

diff --git a/lib/sqlalchemy/dialects/oracle/cx_oracle.py b/lib/sqlalchemy/dialects/oracle/cx_oracle.py
index e8ed3ab5cb2c23da340d60fac1a1c8d7d087ea3d..69ee82bd2345027506a5e13f72ceb1569d1a4fe8 100644 (file)
--- a/lib/sqlalchemy/dialects/oracle/cx_oracle.py
+++ b/lib/sqlalchemy/dialects/oracle/cx_oracle.py
@@ -126,10 +126,15 @@ itself.  These options are always passed directly to :func:`_sa.create_engine`
 
 The parameters accepted by the cx_oracle dialect are as follows:
 
-* ``arraysize`` - set the cx_oracle.arraysize value on cursors, defaulted
-  to 50.  This setting is significant with cx_Oracle as the contents of LOB
-  objects are only readable within a "live" row (e.g. within a batch of
-  50 rows).
+* ``arraysize`` - set the cx_oracle.arraysize value on cursors; defaults
+  to ``None``, indicating that the driver default should be used (typically
+  the value is 100).  This setting controls how many rows are buffered when
+  fetching rows, and can have a significant effect on performance when
+  modified.   The setting is used for both ``cx_Oracle`` as well as
+  ``oracledb``.
+
+  .. versionchanged:: 2.0.26 - changed the default value from 50 to None,
+    to use the default value of the driver itself.
 
 * ``auto_convert_lobs`` - defaults to True; See :ref:`cx_oracle_lob`.
 
@@ -1033,7 +1038,7 @@ class OracleDialect_cx_oracle(OracleDialect):
         self,
         auto_convert_lobs=True,
         coerce_to_decimal=True,
-        arraysize=50,
+        arraysize=None,
         encoding_errors=None,
         threaded=None,
         **kwargs,

diff --git a/lib/sqlalchemy/dialects/oracle/oracledb.py b/lib/sqlalchemy/dialects/oracle/oracledb.py
index 1229573ad1e8245ff54c04b510f56edd1beb4d88..9cdec3b55aef3a46a48a30599b462b6b985ba78f 100644 (file)
--- a/lib/sqlalchemy/dialects/oracle/oracledb.py
+++ b/lib/sqlalchemy/dialects/oracle/oracledb.py
@@ -105,7 +105,7 @@ class OracleDialect_oracledb(_OracleDialect_cx_oracle):
         self,
         auto_convert_lobs=True,
         coerce_to_decimal=True,
-        arraysize=50,
+        arraysize=None,
         encoding_errors=None,
         thick_mode=None,
         **kwargs,

diff --git a/test/requirements.py b/test/requirements.py
index 4a0b365c2b546bd5bf5d699a3ef9de278dd092a7..a5a389441dd12273861c60e929bdec306a82d332 100644 (file)
--- a/test/requirements.py
+++ b/test/requirements.py
@@ -784,7 +784,7 @@ class DefaultRequirements(SuiteRequirements):
         #8221.
 
         """
-        return fails_if(["mssql", "oracle>=12"])
+        return fails_if(["mssql", "oracle < 23"])
 
     @property
     def parens_in_union_contained_select_w_limit_offset(self):