implement batched INSERT..VALUES () () for executemany

the feature is enabled for all built in backends
when RETURNING is used,
except for Oracle that doesn't need it,  and on
psycopg2 and mssql+pyodbc it is used for all INSERT statements,
not just those that use RETURNING.

third party dialects would need to opt in to the new feature
by setting use_insertmanyvalues to True.

Also adds dialect-level guards against using returning
with executemany where we dont have an implementation to
suit it.   execute single w/ returning still defers to the
server without us checking.

Fixes: #6047
Fixes: #7907
Change-Id: I3936d3c00003f02e322f2e43fb949d0e6e568304

1 files changed, 17 insertions, 0 deletions

diff --git a/lib/sqlalchemy/dialects/mysql/provision.py b/lib/sqlalchemy/dialects/mysql/provision.py
index c73875fec..36a5e9f54 100644
--- a/lib/sqlalchemy/dialects/mysql/provision.py
+++ b/lib/sqlalchemy/dialects/mysql/provision.py
@@ -6,6 +6,7 @@ from ...testing.provision import create_db
 from ...testing.provision import drop_db
 from ...testing.provision import generate_driver_url
 from ...testing.provision import temp_table_keyword_args
+from ...testing.provision import upsert
 
 
 @generate_driver_url.for_db("mysql", "mariadb")
@@ -78,3 +79,19 @@ def _mysql_drop_db(cfg, eng, ident):
 @temp_table_keyword_args.for_db("mysql", "mariadb")
 def _mysql_temp_table_keyword_args(cfg, eng):
     return {"prefixes": ["TEMPORARY"]}
+
+
+@upsert.for_db("mariadb")
+def _upsert(cfg, table, returning, set_lambda=None):
+    from sqlalchemy.dialects.mysql import insert
+
+    stmt = insert(table)
+
+    if set_lambda:
+        stmt = stmt.on_duplicate_key_update(**set_lambda(stmt.inserted))
+    else:
+        pk1 = table.primary_key.c[0]
+        stmt = stmt.on_duplicate_key_update({pk1.key: pk1})
+
+    stmt = stmt.returning(*returning)
+    return stmt