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 (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/examples/performance/large_resultsets.py b/examples/performance/large_resultsets.py
index 9c0d9fc4e2155cc976a55c50d6bb5671e6c0985d..b93459150e5719f0f353d48286e33d0ac7b75795 100644 (file)
--- 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 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 78deecf4a24b5bb8d8332855b3d3c510ed702c80..de5be44d90477a6cce36091e462f5cb79d1a4063 100644 (file)
--- 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 1626c825f24020dc9ba2d360f3ca6b41ec31f971..cb6ceeb2652bb72152221f6bffcd6c49469d2196 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):