Assertion failed: virtual bool drizzled::Item_in_subselect::exec(): Assertion `exec_method != MATERIALIZATION || (exec_method == MATERIALIZATION && engine->engine_type() == subselect_engine::HASH_SJ_ENGINE)'

I made an attempt to port the patch over. Also the tests (also attached).

However... not sure if this is anything:

--- /home/stewart/drizzle/working/tests/r/bug588408.result 2010-06-02 06:50:31.242011816 +0300
+++ /home/stewart/drizzle/working/tests/r/bug588408.reject 2010-06-02 06:59:48.430702393 +0300
@@ -118,7 +118,7 @@
 id select_type table type possible_keys key key_len ref rows Extra
 1 PRIMARY <derived2> system NULL NULL NULL NULL 0 const row not found
 3 SUBQUERY t2 ALL NULL NULL NULL NULL 2
-2 DERIVED NULL NULL NULL NULL NULL NULL NULL no matching row in const table
+2 DERIVED empty1 ALL NULL NULL NULL NULL 1

 #
 # 5) Test that subquery materialization is setup for query with
@@ -142,8 +142,9 @@
 SELECT v
 FROM t2);
 id select_type table type possible_keys key key_len ref rows Extra
-1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE noticed after reading const tables
+1 PRIMARY t1 index NULL PRIMARY 4 NULL 2 Using where; Using index
 3 SUBQUERY t2 ALL NULL NULL NULL NULL 2
+2 SUBQUERY t3 index PRIMARY PRIMARY 4 NULL 1 Using where; Using index
 #
 # Cleanup for BUG#46680
 #

I took a look at this as well and it appears that we arrive at the same result sets even if we don't hit the same query plans.

It is my understanding that differences in EXPLAIN plans can be acceptable as the code changes and it might be that we don't need these parts of the test.

The crash is corrected and we produce the same results. However, I'll beat up on the patch with a couple of additional optimizer grammars and post an update on how things went.

On Wed, 02 Jun 2010 15:18:47 -0000, Patrick Crews <email address hidden> wrote:
> The crash is corrected and we produce the same results. However, I'll
> beat up on the patch with a couple of additional optimizer grammars and
> post an update on how things went.

Great.

Perhaps this is one for a comparitive run... maybe involving
explain.... I'm still no optimiser expert :)
--
Stewart Smith

I ran through all of the optimizer/drizzle grammars + a couple of additional ones. No differences were reported, no crashes related to this patch were detected (if we saw a crash, both servers died).

I'm feeling comfortable with this despite the change in EXPLAIN output.../me has some negative thoughts on the labyrinthine optimizer code though.

If anyone wants additional testing, I can do an ExecutionTimeComparator run (checks execution time of two servers and reports if the diff is > user_set_threshold. We can also hack our grammars to see how much EXPLAIN output differs, but we're still getting the correct results for a fairly large range of queries.