Default psycopg2 executemany mode to "values_only"

The psycopg2 dialect now defaults to using the very performant
``execute_values()`` psycopg2 extension for compiled INSERT statements,
and also impements RETURNING support when this extension is used.  This
allows INSERT statements that even include an autoincremented SERIAL
or IDENTITY value to run very fast while still being able to return the
newly generated primary key values.   The ORM will then integrate this
new feature in a separate change.

Implements RETURNING for insert with executemany

Adds support to return_defaults() mode and inserted_primary_key
to support mutiple INSERTed rows, via return_defauls_rows
and inserted_primary_key_rows accessors.

within default execution context, new cached compiler
getters are used to fetch primary keys from rows

inserted_primary_key now returns a plain tuple. this
is not yet a row-like object however this can be
added.

Adds distinct "values_only" and "batch" modes, as
"values" has a lot of benefits but "batch" breaks
cursor.rowcount

psycopg2 minimum version 2.7 so we can remove the
large number of checks for very old versions of
psycopg2

simplify tests to no longer distinguish between
native and non-native json

Fixes: #5401
Change-Id: Ic08fd3423d4c5d16ca50994460c0c234868bd61c

5 files changed, 23 insertions, 10 deletions

diff --git a/lib/sqlalchemy/testing/assertions.py b/lib/sqlalchemy/testing/assertions.py
index 54da06a3d..1ea366dac 100644
--- a/lib/sqlalchemy/testing/assertions.py
+++ b/lib/sqlalchemy/testing/assertions.py
@@ -355,7 +355,6 @@ class AssertsCompiledSQL(object):
         schema_translate_map=None,
         render_schema_translate=False,
         default_schema_name=None,
-        inline_flag=None,
     ):
         if use_default_dialect:
             dialect = default.DefaultDialect()
@@ -451,8 +450,6 @@ class AssertsCompiledSQL(object):
                 },
                 check_post_param,
             )
-        if inline_flag is not None:
-            eq_(c.inline, inline_flag)
 
 
 class ComparesTables(object):
diff --git a/lib/sqlalchemy/testing/assertsql.py b/lib/sqlalchemy/testing/assertsql.py
index 48cbb4694..ef324635e 100644
--- a/lib/sqlalchemy/testing/assertsql.py
+++ b/lib/sqlalchemy/testing/assertsql.py
@@ -106,7 +106,7 @@ class CompiledSQL(SQLMatchRule):
             compiled = execute_observed.clauseelement.compile(
                 dialect=compare_dialect,
                 column_keys=context.compiled.column_keys,
-                inline=context.compiled.inline,
+                for_executemany=context.compiled.for_executemany,
                 schema_translate_map=map_,
             )
         _received_statement = re.sub(r"[\n\t]", "", util.text_type(compiled))
diff --git a/lib/sqlalchemy/testing/requirements.py b/lib/sqlalchemy/testing/requirements.py
index 163276ca9..3e20f8681 100644
--- a/lib/sqlalchemy/testing/requirements.py
+++ b/lib/sqlalchemy/testing/requirements.py
@@ -324,6 +324,20 @@ class SuiteRequirements(Requirements):
         )
 
     @property
+    def insert_executemany_returning(self):
+        """target platform supports RETURNING when INSERT is used with
+        executemany(), e.g. multiple parameter sets, indicating
+        as many rows come back as do parameter sets were passed.
+
+        """
+
+        return exclusions.only_if(
+            lambda config: config.db.dialect.insert_executemany_returning,
+            "%(database)s %(does_support)s 'RETURNING of "
+            "multiple rows with INSERT executemany'",
+        )
+
+    @property
     def returning(self):
         """target platform supports RETURNING for at least one row.
 
diff --git a/lib/sqlalchemy/testing/suite/test_insert.py b/lib/sqlalchemy/testing/suite/test_insert.py
index 65741941f..5b8c343c4 100644
--- a/lib/sqlalchemy/testing/suite/test_insert.py
+++ b/lib/sqlalchemy/testing/suite/test_insert.py
@@ -56,7 +56,7 @@ class LastrowidTest(fixtures.TablesTest):
             self.tables.autoinc_pk.insert(), data="some data"
         )
         pk = connection.scalar(select([self.tables.autoinc_pk.c.id]))
-        eq_(r.inserted_primary_key, [pk])
+        eq_(r.inserted_primary_key, (pk,))
 
     @requirements.dbapi_lastrowid
     def test_native_lastrowid_autoinc(self, connection):
@@ -184,7 +184,7 @@ class InsertBehaviorTest(fixtures.TablesTest):
             )
         )
 
-        eq_(result.inserted_primary_key, [None])
+        eq_(result.inserted_primary_key, (None,))
 
         result = connection.execute(
             select([dest_table.c.data]).order_by(dest_table.c.data)
@@ -204,7 +204,7 @@ class InsertBehaviorTest(fixtures.TablesTest):
                 ),
             )
         )
-        eq_(result.inserted_primary_key, [None])
+        eq_(result.inserted_primary_key, (None,))
 
         result = connection.execute(
             select([dest_table.c.data]).order_by(dest_table.c.data)
@@ -329,7 +329,7 @@ class ReturningTest(fixtures.TablesTest):
             self.tables.autoinc_pk.insert(), data="some data"
         )
         pk = connection.scalar(select([self.tables.autoinc_pk.c.id]))
-        eq_(r.inserted_primary_key, [pk])
+        eq_(r.inserted_primary_key, (pk,))
 
 
 __all__ = ("LastrowidTest", "InsertBehaviorTest", "ReturningTest")
diff --git a/lib/sqlalchemy/testing/suite/test_sequence.py b/lib/sqlalchemy/testing/suite/test_sequence.py
index 55e8e8406..5a1876bc5 100644
--- a/lib/sqlalchemy/testing/suite/test_sequence.py
+++ b/lib/sqlalchemy/testing/suite/test_sequence.py
@@ -46,7 +46,9 @@ class SequenceTest(fixtures.TablesTest):
 
     def test_insert_lastrowid(self, connection):
         r = connection.execute(self.tables.seq_pk.insert(), data="some data")
-        eq_(r.inserted_primary_key, [testing.db.dialect.default_sequence_base])
+        eq_(
+            r.inserted_primary_key, (testing.db.dialect.default_sequence_base,)
+        )
 
     def test_nextval_direct(self, connection):
         r = connection.execute(self.tables.seq_pk.c.id.default)
@@ -57,7 +59,7 @@ class SequenceTest(fixtures.TablesTest):
         r = connection.execute(
             self.tables.seq_opt_pk.insert(), data="some data"
         )
-        eq_(r.inserted_primary_key, [1])
+        eq_(r.inserted_primary_key, (1,))
 
     def _assert_round_trip(self, table, conn):
         row = conn.execute(table.select()).first()