CAST Oracle table_name, owner, others to VARCHAR(128)

Added a CAST(VARCHAR2(128)) to the "table name", "owner", and other
DDL-name parameters as used in reflection queries against Oracle system
views such as ALL_TABLES, ALL_TAB_CONSTRAINTS, etc to better enable
indexing to take place against these columns, as they previously would be
implicitly handled as NVARCHAR2 due to Python's use of Unicode for strings;
these columns are documented in all Oracle versions as being VARCHAR2 with
lengths varying from 30 to 128 characters depending on server version.
Additionally, test support has been enabled for Unicode-named DDL
structures against Oracle databases.

Fixes: #4486
Change-Id: I2787e3f8de1f656318692bd535d6a7f1cef1a841

diff --git a/doc/build/changelog/unreleased_14/4486.rst b/doc/build/changelog/unreleased_14/4486.rst
new file mode 100644 (file)
index 0000000..45007a2
--- /dev/null
+++ b/doc/build/changelog/unreleased_14/4486.rst
@@ -0,0 +1,13 @@
+.. change::
+    :tags: bug, oracle, performance
+    :tickets: 4486
+
+    Added a CAST(VARCHAR2(128)) to the "table name", "owner", and other
+    DDL-name parameters as used in reflection queries against Oracle system
+    views such as ALL_TABLES, ALL_TAB_CONSTRAINTS, etc to better enable
+    indexing to take place against these columns, as they previously would be
+    implicitly handled as NVARCHAR2 due to Python's use of Unicode for strings;
+    these columns are documented in all Oracle versions as being VARCHAR2 with
+    lengths varying from 30 to 128 characters depending on server version.
+    Additionally, test support has been enabled for Unicode-named DDL
+    structures against Oracle databases.

diff --git a/lib/sqlalchemy/dialects/oracle/base.py b/lib/sqlalchemy/dialects/oracle/base.py
index b1d7bc440e486324171d95b1f650e6d4e1653b66..8b790c70c694f092af5bfd890081594cb2409b75 100644 (file)
--- a/lib/sqlalchemy/dialects/oracle/base.py
+++ b/lib/sqlalchemy/dialects/oracle/base.py
@@ -1608,10 +1608,12 @@ class OracleDialect(default.DefaultDialect):
 
         if not schema:
             schema = self.default_schema_name
+
         cursor = connection.execute(
             sql.text(
                 "SELECT table_name FROM all_tables "
-                "WHERE table_name = :name AND owner = :schema_name"
+                "WHERE table_name = CAST(:name AS VARCHAR2(128)) "
+                "AND owner = CAST(:schema_name AS VARCHAR2(128))"
             ),
             dict(
                 name=self.denormalize_name(table_name),
@@ -1665,13 +1667,15 @@ class OracleDialect(default.DefaultDialect):
         clauses = []
         params = {}
         if desired_synonym:
-            clauses.append("synonym_name = :synonym_name")
+            clauses.append(
+                "synonym_name = CAST(:synonym_name AS VARCHAR2(128))"
+            )
             params["synonym_name"] = desired_synonym
         if desired_owner:
-            clauses.append("owner = :desired_owner")
+            clauses.append("owner = CAST(:desired_owner AS VARCHAR2(128))")
             params["desired_owner"] = desired_owner
         if desired_table:
-            clauses.append("table_name = :tname")
+            clauses.append("table_name = CAST(:tname AS VARCHAR2(128))")
             params["tname"] = desired_table
 
         q += " AND ".join(clauses)
@@ -1846,12 +1850,12 @@ class OracleDialect(default.DefaultDialect):
         text = (
             "SELECT %(columns)s "
             "FROM ALL_TABLES%(dblink)s "
-            "WHERE table_name = :table_name"
+            "WHERE table_name = CAST(:table_name AS VARCHAR(128))"
         )
 
         if schema is not None:
             params["owner"] = schema
-            text += " AND owner = :owner "
+            text += " AND owner = CAST(:owner AS VARCHAR(128)) "
         text = text % {"dblink": dblink, "columns": ", ".join(columns)}
 
         result = connection.execute(sql.text(text), params)
@@ -1916,6 +1920,7 @@ class OracleDialect(default.DefaultDialect):
             identity_cols = "NULL as default_on_null, NULL as identity_options"
 
         params = {"table_name": table_name}
+
         text = """
             SELECT
                 col.column_name,
@@ -1933,7 +1938,7 @@ class OracleDialect(default.DefaultDialect):
             ON col.table_name = com.table_name
             AND col.column_name = com.column_name
             AND col.owner = com.owner
-            WHERE col.table_name = :table_name
+            WHERE col.table_name = CAST(:table_name AS VARCHAR2(128))
             AND col.hidden_column = 'NO'
         """
         if schema is not None:
@@ -2076,7 +2081,8 @@ class OracleDialect(default.DefaultDialect):
         COMMENT_SQL = """
             SELECT comments
             FROM all_tab_comments
-            WHERE table_name = :table_name AND owner = :schema_name
+            WHERE table_name = CAST(:table_name AS VARCHAR(128))
+            AND owner = CAST(:schema_name AS VARCHAR(128))
         """
 
         c = connection.execute(
@@ -2117,7 +2123,7 @@ class OracleDialect(default.DefaultDialect):
             "\na.index_name = b.index_name "
             "\nAND a.table_owner = b.table_owner "
             "\nAND a.table_name = b.table_name "
-            "\nAND a.table_name = :table_name "
+            "\nAND a.table_name = CAST(:table_name AS VARCHAR(128))"
         )
 
         if schema is not None:
@@ -2209,13 +2215,13 @@ class OracleDialect(default.DefaultDialect):
             "\nFROM all_constraints%(dblink)s ac,"
             "\nall_cons_columns%(dblink)s loc,"
             "\nall_cons_columns%(dblink)s rem"
-            "\nWHERE ac.table_name = :table_name"
+            "\nWHERE ac.table_name = CAST(:table_name AS VARCHAR2(128))"
             "\nAND ac.constraint_type IN ('R','P', 'U', 'C')"
         )
 
         if schema is not None:
             params["owner"] = schema
-            text += "\nAND ac.owner = :owner"
+            text += "\nAND ac.owner = CAST(:owner AS VARCHAR2(128))"
 
         text += (
             "\nAND ac.owner = loc.owner"

diff --git a/test/requirements.py b/test/requirements.py
index 6786c8dafcd9b44953950beda9e642552f5e9618..644c01f758ee9526440b1c334e0feba9fe93e5db 100644 (file)
--- a/test/requirements.py
+++ b/test/requirements.py
@@ -900,7 +900,6 @@ class DefaultRequirements(SuiteRequirements):
 
         return skip_if(
             [
-                no_support("oracle", "FIXME: no support in database?"),
                 no_support("sybase", "FIXME: guessing, needs confirmation"),
                 no_support("mssql+pymssql", "no FreeTDS support"),
             ]