Fix yet another issue with step generation in partition pruning.

Commit 13838740f fixed some issues with step generation in partition
pruning, but there was yet another one: get_steps_using_prefix() assumes
that clauses in the passed-in prefix list are sorted in ascending order
of their partition key numbers, but the caller failed to ensure this for
range partitioning, which led to an assertion failure in debug builds.
Adjust the caller function to arrange the clauses in the prefix list in
the required order for range partitioning.

Back-patch to v11, like the previous commit.

Patch by me, reviewed by Amit Langote.

Discussion: https://postgr.es/m/CAPmGK16jkXiFG0YqMbU66wte-oJTfW6D1HaNvQf%3D%2B5o9%3Dm55wQ%40mail.gmail.com

diff --git a/src/backend/partitioning/partprune.c b/src/backend/partitioning/partprune.c
index 253c6906498249ae58ca5860612f8b36af1d71bf..6268623d56994a753e6fe6ce0354593d927e3a37 100644 (file)
--- a/src/backend/partitioning/partprune.c
+++ b/src/backend/partitioning/partprune.c
@@ -1362,7 +1362,6 @@ gen_prune_steps_from_opexps(GeneratePruningStepsContext *context,
                List       *eq_clauses = btree_clauses[BTEqualStrategyNumber];
                List       *le_clauses = btree_clauses[BTLessEqualStrategyNumber];
                List       *ge_clauses = btree_clauses[BTGreaterEqualStrategyNumber];
-               bool        pk_has_clauses[PARTITION_MAX_KEYS];
                int         strat;
 
                /*
@@ -1382,10 +1381,15 @@ gen_prune_steps_from_opexps(GeneratePruningStepsContext *context,
                    foreach(lc, btree_clauses[strat])
                    {
                        PartClauseInfo *pc = lfirst(lc);
+                       ListCell   *eq_start;
+                       ListCell   *le_start;
+                       ListCell   *ge_start;
                        ListCell   *lc1;
                        List       *prefix = NIL;
                        List       *pc_steps;
                        bool        prefix_valid = true;
+                       bool        pk_has_clauses;
+                       int         keyno;
 
                        /*
                         * If this is a clause for the first partition key,
@@ -1410,79 +1414,96 @@ gen_prune_steps_from_opexps(GeneratePruningStepsContext *context,
                            continue;
                        }
 
-                       /* (Re-)initialize the pk_has_clauses array */
-                       Assert(pc->keyno > 0);
-                       for (i = 0; i < pc->keyno; i++)
-                           pk_has_clauses[i] = false;
+                       eq_start = list_head(eq_clauses);
+                       le_start = list_head(le_clauses);
+                       ge_start = list_head(ge_clauses);
 
                        /*
-                        * Expressions from = clauses can always be in the
-                        * prefix, provided they're from an earlier key.
+                        * We arrange clauses into prefix in ascending order
+                        * of their partition key numbers.
                         */
-                       foreach(lc1, eq_clauses)
+                       for (keyno = 0; keyno < pc->keyno; keyno++)
                        {
-                           PartClauseInfo *eqpc = lfirst(lc1);
+                           pk_has_clauses = false;
 
-                           if (eqpc->keyno == pc->keyno)
-                               break;
-                           if (eqpc->keyno < pc->keyno)
+                           /*
+                            * Expressions from = clauses can always be in the
+                            * prefix, provided they're from an earlier key.
+                            */
+                           for_each_cell(lc1, eq_clauses, eq_start)
                            {
-                               prefix = lappend(prefix, eqpc);
-                               pk_has_clauses[eqpc->keyno] = true;
-                           }
-                       }
+                               PartClauseInfo *eqpc = lfirst(lc1);
 
-                       /*
-                        * If we're generating steps for </<= strategy, we can
-                        * add other <= clauses to the prefix, provided
-                        * they're from an earlier key.
-                        */
-                       if (strat == BTLessStrategyNumber ||
-                           strat == BTLessEqualStrategyNumber)
-                       {
-                           foreach(lc1, le_clauses)
-                           {
-                               PartClauseInfo *lepc = lfirst(lc1);
-
-                               if (lepc->keyno == pc->keyno)
+                               if (eqpc->keyno == keyno)
+                               {
+                                   prefix = lappend(prefix, eqpc);
+                                   pk_has_clauses = true;
+                               }
+                               else
+                               {
+                                   Assert(eqpc->keyno > keyno);
                                    break;
-                               if (lepc->keyno < pc->keyno)
+                               }
+                           }
+                           eq_start = lc1;
+
+                           /*
+                            * If we're generating steps for </<= strategy, we
+                            * can add other <= clauses to the prefix,
+                            * provided they're from an earlier key.
+                            */
+                           if (strat == BTLessStrategyNumber ||
+                               strat == BTLessEqualStrategyNumber)
+                           {
+                               for_each_cell(lc1, le_clauses, le_start)
                                {
-                                   prefix = lappend(prefix, lepc);
-                                   pk_has_clauses[lepc->keyno] = true;
+                                   PartClauseInfo *lepc = lfirst(lc1);
+
+                                   if (lepc->keyno == keyno)
+                                   {
+                                       prefix = lappend(prefix, lepc);
+                                       pk_has_clauses = true;
+                                   }
+                                   else
+                                   {
+                                       Assert(lepc->keyno > keyno);
+                                       break;
+                                   }
                                }
+                               le_start = lc1;
                            }
-                       }
 
-                       /*
-                        * If we're generating steps for >/>= strategy, we can
-                        * add other >= clauses to the prefix, provided
-                        * they're from an earlier key.
-                        */
-                       if (strat == BTGreaterStrategyNumber ||
-                           strat == BTGreaterEqualStrategyNumber)
-                       {
-                           foreach(lc1, ge_clauses)
+                           /*
+                            * If we're generating steps for >/>= strategy, we
+                            * can add other >= clauses to the prefix,
+                            * provided they're from an earlier key.
+                            */
+                           if (strat == BTGreaterStrategyNumber ||
+                               strat == BTGreaterEqualStrategyNumber)
                            {
-                               PartClauseInfo *gepc = lfirst(lc1);
-
-                               if (gepc->keyno == pc->keyno)
-                                   break;
-                               if (gepc->keyno < pc->keyno)
+                               for_each_cell(lc1, ge_clauses, ge_start)
                                {
-                                   prefix = lappend(prefix, gepc);
-                                   pk_has_clauses[gepc->keyno] = true;
+                                   PartClauseInfo *gepc = lfirst(lc1);
+
+                                   if (gepc->keyno == keyno)
+                                   {
+                                       prefix = lappend(prefix, gepc);
+                                       pk_has_clauses = true;
+                                   }
+                                   else
+                                   {
+                                       Assert(gepc->keyno > keyno);
+                                       break;
+                                   }
                                }
+                               ge_start = lc1;
                            }
-                       }
 
-                       /*
-                        * Check whether every earlier partition key has at
-                        * least one clause.
-                        */
-                       for (i = 0; i < pc->keyno; i++)
-                       {
-                           if (!pk_has_clauses[i])
+                           /*
+                            * If this key has no clauses, prefix is not valid
+                            * anymore.
+                            */
+                           if (!pk_has_clauses)
                            {
                                prefix_valid = false;
                                break;
@@ -2241,6 +2262,9 @@ match_clause_to_partition_key(GeneratePruningStepsContext *context,
  * non-NULL, but they must ensure that prefix contains at least one clause
  * for each of the partition keys other than those specified in step_nullkeys
  * and step_lastkeyno.
+ *
+ * For both cases, callers must also ensure that clauses in prefix are sorted
+ * in ascending order of their partition key numbers.
  */
 static List *
 get_steps_using_prefix(GeneratePruningStepsContext *context,

diff --git a/src/test/regress/expected/partition_prune.out b/src/test/regress/expected/partition_prune.out
index 687cf8c5f41547d1e80a1c08318c5b38e6041351..50d2a7e4b9754f469bc85e079a0578cd929d4095 100644 (file)
--- a/src/test/regress/expected/partition_prune.out
+++ b/src/test/regress/expected/partition_prune.out
@@ -3711,6 +3711,16 @@ explain (costs off) select * from rp_prefix_test3 where a >= 1 and b >= 1 and b
    Filter: ((a >= 1) AND (b >= 1) AND (b >= 2) AND (c >= 2) AND (d >= 0))
 (2 rows)
 
+-- Test that get_steps_using_prefix() handles a prefix that contains multiple
+-- clauses for the partition key b (ie, b >= 1 and b = 2)  (This also tests
+-- that the caller arranges clauses in that prefix in the required order)
+explain (costs off) select * from rp_prefix_test3 where a >= 1 and b >= 1 and b = 2 and c = 2 and d >= 0;
+                               QUERY PLAN                               
+------------------------------------------------------------------------
+ Seq Scan on rp_prefix_test3_p2 rp_prefix_test3
+   Filter: ((a >= 1) AND (b >= 1) AND (d >= 0) AND (b = 2) AND (c = 2))
+(2 rows)
+
 create table hp_prefix_test (a int, b int, c int, d int) partition by hash (a part_test_int4_ops, b part_test_int4_ops, c part_test_int4_ops, d part_test_int4_ops);
 create table hp_prefix_test_p1 partition of hp_prefix_test for values with (modulus 2, remainder 0);
 create table hp_prefix_test_p2 partition of hp_prefix_test for values with (modulus 2, remainder 1);

diff --git a/src/test/regress/sql/partition_prune.sql b/src/test/regress/sql/partition_prune.sql
index 93ef9dc1f340767672bdbb82b8583e5169993322..1e904a8c5b7b3707982b3898415ab609148864f4 100644 (file)
--- a/src/test/regress/sql/partition_prune.sql
+++ b/src/test/regress/sql/partition_prune.sql
@@ -1080,6 +1080,11 @@ create table rp_prefix_test3_p2 partition of rp_prefix_test3 for values from (2,
 -- clauses for the partition key b (ie, b >= 1 and b >= 2)
 explain (costs off) select * from rp_prefix_test3 where a >= 1 and b >= 1 and b >= 2 and c >= 2 and d >= 0;
 
+-- Test that get_steps_using_prefix() handles a prefix that contains multiple
+-- clauses for the partition key b (ie, b >= 1 and b = 2)  (This also tests
+-- that the caller arranges clauses in that prefix in the required order)
+explain (costs off) select * from rp_prefix_test3 where a >= 1 and b >= 1 and b = 2 and c = 2 and d >= 0;
+
 create table hp_prefix_test (a int, b int, c int, d int) partition by hash (a part_test_int4_ops, b part_test_int4_ops, c part_test_int4_ops, d part_test_int4_ops);
 create table hp_prefix_test_p1 partition of hp_prefix_test for values with (modulus 2, remainder 0);
 create table hp_prefix_test_p2 partition of hp_prefix_test for values with (modulus 2, remainder 1);