Fix runtime partition pruning for HASH partitioned tables

This could only affect HASH partitioned tables with at least 2 partition
key columns.

If partition pruning was delayed until execution and the query contained
an IS NULL qual on one of the partitioned keys, and some subsequent
partitioned key was being compared to a non-Const, then this could result
in a crash due to the incorrect keyno being used to calculate the
stateidx for the expression evaluation code.

Here we fix this by properly skipping partitioned keys which have a
nullkey set.  Effectively, this must be the same as what's going on
inside perform_pruning_base_step().

Sergei Glukhov also provided a patch, but that's not what's being used
here.

Reported-by: Sergei Glukhov
Reviewed-by: tender wang, Sergei Glukhov
Discussion: https://postgr.es/m/d05b26fa-af54-27e1-f693-6c31590802fa@postgrespro.ru
Backpatch-through: 11, where runtime partition pruning was added.

diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index 73bc5bb95858c823ea945e6aaeef2024b439032e..ba5a58d027c9233c751a1b681934d1eb5fcdc6b8 100644 (file)
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -1956,7 +1956,7 @@ InitPartitionPruneContext(PartitionPruneContext *context,
    foreach(lc, pruning_steps)
    {
        PartitionPruneStepOp *step = (PartitionPruneStepOp *) lfirst(lc);
-       ListCell   *lc2;
+       ListCell   *lc2 = list_head(step->exprs);
        int         keyno;
 
        /* not needed for other step kinds */
@@ -1965,34 +1965,39 @@ InitPartitionPruneContext(PartitionPruneContext *context,
 
        Assert(list_length(step->exprs) <= partnatts);
 
-       keyno = 0;
-       foreach(lc2, step->exprs)
+       for (keyno = 0; keyno < partnatts; keyno++)
        {
-           Expr       *expr = (Expr *) lfirst(lc2);
+           if (bms_is_member(keyno, step->nullkeys))
+               continue;
 
-           /* not needed for Consts */
-           if (!IsA(expr, Const))
+           if (lc2 != NULL)
            {
-               int         stateidx = PruneCxtStateIdx(partnatts,
-                                                       step->step.step_id,
-                                                       keyno);
+               Expr       *expr = lfirst(lc2);
 
-               /*
-                * When planstate is NULL, pruning_steps is known not to
-                * contain any expressions that depend on the parent plan.
-                * Information of any available EXTERN parameters must be
-                * passed explicitly in that case, which the caller must have
-                * made available via econtext.
-                */
-               if (planstate == NULL)
-                   context->exprstates[stateidx] =
-                       ExecInitExprWithParams(expr,
-                                              econtext->ecxt_param_list_info);
-               else
-                   context->exprstates[stateidx] =
-                       ExecInitExpr(expr, context->planstate);
+               /* not needed for Consts */
+               if (!IsA(expr, Const))
+               {
+                   int         stateidx = PruneCxtStateIdx(partnatts,
+                                                           step->step.step_id,
+                                                           keyno);
+
+                   /*
+                    * When planstate is NULL, pruning_steps is known not to
+                    * contain any expressions that depend on the parent plan.
+                    * Information of any available EXTERN parameters must be
+                    * passed explicitly in that case, which the caller must
+                    * have made available via econtext.
+                    */
+                   if (planstate == NULL)
+                       context->exprstates[stateidx] =
+                           ExecInitExprWithParams(expr,
+                                                  econtext->ecxt_param_list_info);
+                   else
+                       context->exprstates[stateidx] =
+                           ExecInitExpr(expr, context->planstate);
+               }
+               lc2 = lnext(step->exprs, lc2);
            }
-           keyno++;
        }
    }
 }

diff --git a/src/test/regress/expected/partition_prune.out b/src/test/regress/expected/partition_prune.out
index c90c841e061514a6ddfdda01cbd636fe38be270a..c5bc6c33f59ba559bd918fe1ec0326727e6cf4a8 100644 (file)
--- a/src/test/regress/expected/partition_prune.out
+++ b/src/test/regress/expected/partition_prune.out
@@ -1948,7 +1948,6 @@ explain (costs off) select * from hp where a = 1 and b = 'abcde' and
    One-Time Filter: false
 (2 rows)
 
-drop table hp;
 --
 -- Test runtime partition pruning
 --
@@ -2070,6 +2069,27 @@ explain (analyze, costs off, summary off, timing off) execute ab_q3 (2, 2);
          Filter: ((b >= $1) AND (b <= $2) AND (a < $0))
 (10 rows)
 
+--
+-- Test runtime pruning with hash partitioned tables
+--
+-- recreate partitions dropped above
+create table hp1 partition of hp for values with (modulus 4, remainder 1);
+create table hp2 partition of hp for values with (modulus 4, remainder 2);
+create table hp3 partition of hp for values with (modulus 4, remainder 3);
+-- Ensure we correctly prune unneeded partitions when there is an IS NULL qual
+prepare hp_q1 (text) as
+select * from hp where a is null and b = $1;
+explain (costs off) execute hp_q1('xxx');
+                 QUERY PLAN                 
+--------------------------------------------
+ Append
+   Subplans Removed: 3
+   ->  Seq Scan on hp2 hp_1
+         Filter: ((a IS NULL) AND (b = $1))
+(4 rows)
+
+deallocate hp_q1;
+drop table hp;
 -- Test a backwards Append scan
 create table list_part (a int) partition by list (a);
 create table list_part1 partition of list_part for values in (1);

diff --git a/src/test/regress/sql/partition_prune.sql b/src/test/regress/sql/partition_prune.sql
index 02dc472c101c8506435a549238f0caca6e951389..ff7e535a6675aa4aaac87a4730222fc26f3f6165 100644 (file)
--- a/src/test/regress/sql/partition_prune.sql
+++ b/src/test/regress/sql/partition_prune.sql
@@ -384,8 +384,6 @@ drop table hp2;
 explain (costs off) select * from hp where a = 1 and b = 'abcde' and
   (c = 2 or c = 3);
 
-drop table hp;
-
 --
 -- Test runtime partition pruning
 --
@@ -436,6 +434,25 @@ select a from ab where b between $1 and $2 and a < (select 3);
 
 explain (analyze, costs off, summary off, timing off) execute ab_q3 (2, 2);
 
+--
+-- Test runtime pruning with hash partitioned tables
+--
+
+-- recreate partitions dropped above
+create table hp1 partition of hp for values with (modulus 4, remainder 1);
+create table hp2 partition of hp for values with (modulus 4, remainder 2);
+create table hp3 partition of hp for values with (modulus 4, remainder 3);
+
+-- Ensure we correctly prune unneeded partitions when there is an IS NULL qual
+prepare hp_q1 (text) as
+select * from hp where a is null and b = $1;
+
+explain (costs off) execute hp_q1('xxx');
+
+deallocate hp_q1;
+
+drop table hp;
+
 -- Test a backwards Append scan
 create table list_part (a int) partition by list (a);
 create table list_part1 partition of list_part for values in (1);