From: Federico Caselli <cfederico87@gmail.com>
Date: Fri, 12 Jan 2024 18:17:30 +0000 (+0100)
Subject: Oracle default arraysize is now set by the driver
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=c8214ad4389284dc9508e49aeca701e5bf164454;p=thirdparty%2Fsqlalchemy%2Fsqlalchemy.git

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
---

diff --git a/doc/build/changelog/unreleased_20/10877.rst b/doc/build/changelog/unreleased_20/10877.rst
new file mode 100644
index 0000000000..8aaac983b4
--- /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/examples/performance/large_resultsets.py b/examples/performance/large_resultsets.py
index 9c0d9fc4e2..b93459150e 100644
--- a/examples/performance/large_resultsets.py
+++ b/examples/performance/large_resultsets.py
@@ -15,6 +15,7 @@ provide a huge amount of functionality.
 """
 from sqlalchemy import Column
 from sqlalchemy import create_engine
+from sqlalchemy import Identity
 from sqlalchemy import Integer
 from sqlalchemy import String
 from sqlalchemy.ext.declarative import declarative_base
@@ -29,7 +30,7 @@ engine = None
 
 class Customer(Base):
     __tablename__ = "customer"
-    id = Column(Integer, primary_key=True)
+    id = Column(Integer, Identity(), primary_key=True)
     name = Column(String(255))
     description = Column(String(255))
 
diff --git a/lib/sqlalchemy/dialects/oracle/cx_oracle.py b/lib/sqlalchemy/dialects/oracle/cx_oracle.py
index e8ed3ab5cb..69ee82bd23 100644
--- 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 78deecf4a2..de5be44d90 100644
--- a/lib/sqlalchemy/dialects/oracle/oracledb.py
+++ b/lib/sqlalchemy/dialects/oracle/oracledb.py
@@ -101,7 +101,7 @@ 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 1626c825f2..cb6ceeb265 100644
--- 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):