Re: POC: postgres_fdw insert batching

Hi,
The assignment to resultRelInfo is done when junk_filter_needed is true:

        if (junk_filter_needed)
        {
            resultRelInfo = mtstate->resultRelInfo;

Should the code for determining batch size access mtstate->resultRelInfo
directly ?

diff --git a/src/backend/executor/nodeModifyTable.c
b/src/backend/executor/nodeModifyTable.c
index 9c36860704..a6a814454d 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2798,17 +2798,17 @@ ExecInitModifyTable(ModifyTable *node, EState
*estate, int eflags)
      * size (a FDW may support batching, but it may be disabled for the
      * server/table).
      */
-    if (!resultRelInfo->ri_usesFdwDirectModify &&
+    if (!mtstate->resultRelInfo->ri_usesFdwDirectModify &&
         operation == CMD_INSERT &&
-        resultRelInfo->ri_FdwRoutine != NULL &&
-        resultRelInfo->ri_FdwRoutine->GetForeignModifyBatchSize &&
-        resultRelInfo->ri_FdwRoutine->ExecForeignBatchInsert)
-        resultRelInfo->ri_BatchSize =
-
 resultRelInfo->ri_FdwRoutine->GetForeignModifyBatchSize(resultRelInfo);
+        mtstate->resultRelInfo->ri_FdwRoutine != NULL &&
+        mtstate->resultRelInfo->ri_FdwRoutine->GetForeignModifyBatchSize &&
+        mtstate->resultRelInfo->ri_FdwRoutine->ExecForeignBatchInsert)
+        mtstate->resultRelInfo->ri_BatchSize =
+
 mtstate->resultRelInfo->ri_FdwRoutine->GetForeignModifyBatchSize(mtstate->resultRelInfo);
     else
-        resultRelInfo->ri_BatchSize = 1;
+        mtstate->resultRelInfo->ri_BatchSize = 1;

-    Assert(resultRelInfo->ri_BatchSize >= 1);
+    Assert(mtstate->resultRelInfo->ri_BatchSize >= 1);

     /*
      * Lastly, if this is not the primary (canSetTag) ModifyTable node,
add it

Cheers

On Wed, Jan 20, 2021 at 3:52 PM Tomas Vondra <tomas.vondra@enterprisedb.com>
wrote:

> Hmm, seems that florican doesn't like this :-(
>
>
> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=florican&dt=2021-01-20%2023%3A08%3A15
>
> It's a i386 machine running FreeBSD, so not sure what exactly it's picky
> about. But when I tried running this under valgrind, I get some strange
> failures in the new chunk in ExecInitModifyTable:
>
>    /*
>     * Determine if the FDW supports batch insert and determine the batch
>     * size (a FDW may support batching, but it may be disabled for the
>     * server/table).
>     */
>    if (!resultRelInfo->ri_usesFdwDirectModify &&
>        operation == CMD_INSERT &&
>        resultRelInfo->ri_FdwRoutine != NULL &&
>        resultRelInfo->ri_FdwRoutine->GetForeignModifyBatchSize &&
>        resultRelInfo->ri_FdwRoutine->ExecForeignBatchInsert)
>        resultRelInfo->ri_BatchSize =
>
> resultRelInfo->ri_FdwRoutine->GetForeignModifyBatchSize(resultRelInfo);
>    else
>        resultRelInfo->ri_BatchSize = 1;
>
>    Assert(resultRelInfo->ri_BatchSize >= 1);
>
> It seems as if the resultRelInfo is not initialized, or something like
> that. I wouldn't be surprised if the 32-bit machine was pickier and
> failing because of that.
>
> A sample of the valgrind log is attached. It's pretty much just
> repetitions of these three reports.
>
> regards
>
> --
> Tomas Vondra
> EnterpriseDB: http://www.enterprisedb.com
> The Enterprise PostgreSQL Company
>