Convert schema_translate to a post compile

Revised the :paramref:`.Connection.execution_options.schema_translate_map`
feature such that the processing of the SQL statement to receive a specific
schema name occurs within the execution phase of the statement, rather than
at the compile phase.   This is to support the statement being efficiently
cached.   Previously, the current schema being rendered into the statement
for a particular run would be considered as part of the cache key itself,
meaning that for a run against hundreds of schemas, there would be hundreds
of cache keys, rendering the cache much less performant.  The new behavior
is that the rendering is done in a similar  manner as the "post compile"
rendering added in 1.4 as part of :ticket:`4645`, :ticket:`4808`.

Fixes: #5004
Change-Id: Ia5c89eb27cc8dc2c5b8e76d6c07c46290a7901b6

2 files changed, 47 insertions, 5 deletions

diff --git a/test/sql/test_compiler.py b/test/sql/test_compiler.py
index 033da10a3..ef3e5d26e 100644
--- a/test/sql/test_compiler.py
+++ b/test/sql/test_compiler.py
@@ -3960,21 +3960,40 @@ class DDLTest(fixtures.TestBase, AssertsCompiledSQL):
 
         self.assert_compile(
             schema.CreateTable(t1),
+            "CREATE TABLE [SCHEMA__none].t1 (q INTEGER)",
+            schema_translate_map=schema_translate_map,
+        )
+        self.assert_compile(
+            schema.CreateTable(t1),
             "CREATE TABLE z.t1 (q INTEGER)",
             schema_translate_map=schema_translate_map,
+            render_schema_translate=True,
         )
 
         self.assert_compile(
             schema.CreateTable(t2),
+            "CREATE TABLE [SCHEMA_foo].t2 (q INTEGER)",
+            schema_translate_map=schema_translate_map,
+        )
+        self.assert_compile(
+            schema.CreateTable(t2),
             "CREATE TABLE bat.t2 (q INTEGER)",
             schema_translate_map=schema_translate_map,
+            render_schema_translate=True,
         )
 
         self.assert_compile(
             schema.CreateTable(t3),
-            "CREATE TABLE t3 (q INTEGER)",
+            "CREATE TABLE [SCHEMA_bar].t3 (q INTEGER)",
             schema_translate_map=schema_translate_map,
         )
+        self.assert_compile(
+            schema.CreateTable(t3),
+            "CREATE TABLE main.t3 (q INTEGER)",
+            schema_translate_map=schema_translate_map,
+            render_schema_translate=True,
+            default_schema_name="main",
+        )
 
     def test_schema_translate_map_sequence(self):
         s1 = schema.Sequence("s1")
@@ -3985,19 +4004,19 @@ class DDLTest(fixtures.TestBase, AssertsCompiledSQL):
 
         self.assert_compile(
             schema.CreateSequence(s1),
-            "CREATE SEQUENCE z.s1",
+            "CREATE SEQUENCE [SCHEMA__none].s1",
             schema_translate_map=schema_translate_map,
         )
 
         self.assert_compile(
             schema.CreateSequence(s2),
-            "CREATE SEQUENCE bat.s2",
+            "CREATE SEQUENCE [SCHEMA_foo].s2",
             schema_translate_map=schema_translate_map,
         )
 
         self.assert_compile(
             schema.CreateSequence(s3),
-            "CREATE SEQUENCE s3",
+            "CREATE SEQUENCE [SCHEMA_bar].s3",
             schema_translate_map=schema_translate_map,
         )
 
@@ -4135,6 +4154,7 @@ class SchemaTest(fixtures.TestBase, AssertsCompiledSQL):
             "bar.mytable.description FROM bar.mytable "
             "WHERE bar.mytable.name = :name_1",
             schema_translate_map=schema_translate_map,
+            render_schema_translate=True,
         )
 
         self.assert_compile(
@@ -4143,6 +4163,7 @@ class SchemaTest(fixtures.TestBase, AssertsCompiledSQL):
             "foob.remotetable.value FROM foob.remotetable "
             "WHERE foob.remotetable.value = :value_1",
             schema_translate_map=schema_translate_map,
+            render_schema_translate=True,
         )
 
         schema_translate_map = {"remote_owner": "foob"}
@@ -4155,6 +4176,7 @@ class SchemaTest(fixtures.TestBase, AssertsCompiledSQL):
             "foob.remotetable.value FROM mytable JOIN foob.remotetable "
             "ON mytable.myid = foob.remotetable.rem_id",
             schema_translate_map=schema_translate_map,
+            render_schema_translate=True,
         )
 
     def test_schema_translate_aliases(self):
@@ -4185,12 +4207,25 @@ class SchemaTest(fixtures.TestBase, AssertsCompiledSQL):
 
         self.assert_compile(
             stmt,
+            "SELECT [SCHEMA__none].myothertable.otherid, "
+            "[SCHEMA__none].myothertable.othername, "
+            "mytable_1.myid, mytable_1.name, mytable_1.description "
+            "FROM [SCHEMA__none].myothertable JOIN "
+            "[SCHEMA__none].mytable AS mytable_1 "
+            "ON [SCHEMA__none].myothertable.otherid = mytable_1.myid "
+            "WHERE mytable_1.name = :name_1",
+            schema_translate_map=schema_translate_map,
+        )
+
+        self.assert_compile(
+            stmt,
             "SELECT bar.myothertable.otherid, bar.myothertable.othername, "
             "mytable_1.myid, mytable_1.name, mytable_1.description "
             "FROM bar.myothertable JOIN bar.mytable AS mytable_1 "
             "ON bar.myothertable.otherid = mytable_1.myid "
             "WHERE mytable_1.name = :name_1",
             schema_translate_map=schema_translate_map,
+            render_schema_translate=True,
         )
 
     def test_schema_translate_crud(self):
@@ -4209,6 +4244,7 @@ class SchemaTest(fixtures.TestBase, AssertsCompiledSQL):
             table1.insert().values(description="foo"),
             "INSERT INTO bar.mytable (description) VALUES (:description)",
             schema_translate_map=schema_translate_map,
+            render_schema_translate=True,
         )
 
         self.assert_compile(
@@ -4218,17 +4254,20 @@ class SchemaTest(fixtures.TestBase, AssertsCompiledSQL):
             "UPDATE bar.mytable SET description=:description "
             "WHERE bar.mytable.name = :name_1",
             schema_translate_map=schema_translate_map,
+            render_schema_translate=True,
         )
         self.assert_compile(
             table1.delete().where(table1.c.name == "hi"),
             "DELETE FROM bar.mytable WHERE bar.mytable.name = :name_1",
             schema_translate_map=schema_translate_map,
+            render_schema_translate=True,
         )
 
         self.assert_compile(
             table4.insert().values(value="there"),
             "INSERT INTO foob.remotetable (value) VALUES (:value)",
             schema_translate_map=schema_translate_map,
+            render_schema_translate=True,
         )
 
         self.assert_compile(
@@ -4238,6 +4277,7 @@ class SchemaTest(fixtures.TestBase, AssertsCompiledSQL):
             "UPDATE foob.remotetable SET value=:value "
             "WHERE foob.remotetable.value = :value_1",
             schema_translate_map=schema_translate_map,
+            render_schema_translate=True,
         )
 
         self.assert_compile(
@@ -4245,6 +4285,7 @@ class SchemaTest(fixtures.TestBase, AssertsCompiledSQL):
             "DELETE FROM foob.remotetable WHERE "
             "foob.remotetable.value = :value_1",
             schema_translate_map=schema_translate_map,
+            render_schema_translate=True,
         )
 
     def test_alias(self):
diff --git a/test/sql/test_ddlemit.py b/test/sql/test_ddlemit.py
index 13300f0b5..667891236 100644
--- a/test/sql/test_ddlemit.py
+++ b/test/sql/test_ddlemit.py
@@ -28,7 +28,8 @@ class EmitDDLTest(fixtures.TestBase):
                 has_index=Mock(side_effect=has_index),
                 supports_comments=True,
                 inline_comments=False,
-            )
+            ),
+            _schema_translate_map=None,
         )
 
     def _mock_create_fixture(