Add wait events for checkpoint delay mechanism.

When MyProc->delayChkptFlags is set to temporarily block phase
transitions in a concurrent checkpoint, the checkpointer enters a
sleep-poll loop to wait for the flag to be cleared.  We should show that
as a wait event in the pg_stat_activity view.

Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/CA%2BhUKGL7Whi8iwKbzkbn_1fixH3Yy8aAPz7mfq6Hpj7FeJrKMg%40mail.gmail.com

doc/src/sgml/config.sgml

@@ -5271,13 +5271,14 @@ ANY <replaceable class="parameter">num_sync</replaceable> ( <replaceable class="
       <listitem>
        <para>
         Enables or disables the query planner's use of partitionwise grouping
-        or aggregation, which allows grouping or aggregation on a partitioned
+        or aggregation, which allows grouping or aggregation on partitioned
-        tables performed separately for each partition.  If the <literal>GROUP
+        tables to be performed separately for each partition.  If the
-        BY</literal> clause does not include the partition keys, only partial
+        <literal>GROUP BY</literal> clause does not include the partition
-        aggregation can be performed on a per-partition basis, and
+        keys, only partial aggregation can be performed on a per-partition
-        finalization must be performed later.  Because partitionwise grouping
+        basis, and finalization must be performed later.  Because
-        or aggregation can use significantly more CPU time and memory during
+        partitionwise grouping or aggregation can use significantly more CPU
-        planning, the default is <literal>off</literal>.
+        time and memory during planning, the default is
+        <literal>off</literal>.
        </para>
       </listitem>
      </varlistentry>

doc/src/sgml/func.sgml

@@ -10738,6 +10738,13 @@ SELECT TIMESTAMP '2001-02-16 20:38:40' AT TIME ZONE 'Asia/Tokyo' AT TIME ZONE 'A
     <literal><replaceable>timestamp</replaceable> AT TIME ZONE
     <replaceable>zone</replaceable></literal>.
    </para>
+
+   <para>
+    The function <literal><function>timezone</function>(<replaceable>zone</replaceable>,
+    <replaceable>time</replaceable>)</literal> is equivalent to the SQL-conforming construct
+    <literal><replaceable>time</replaceable> AT TIME ZONE
+    <replaceable>zone</replaceable></literal>.
+   </para>
   </sect2>
 
   <sect2 id="functions-datetime-current">

src/backend/access/transam/xlog.c

@@ -792,59 +792,74 @@ XLogInsertRecord(XLogRecData *rdata,
 	 *----------
 	 */
 	START_CRIT_SECTION();
-	if (isLogSwitch)
+
-		WALInsertLockAcquireExclusive();
+	if (likely(!isLogSwitch))
-	else
+	{
 		WALInsertLockAcquire();
 
-	/*
-	 * Check to see if my copy of RedoRecPtr is out of date. If so, may have
-	 * to go back and have the caller recompute everything. This can only
-	 * happen just after a checkpoint, so it's better to be slow in this case
-	 * and fast otherwise.
-	 *
-	 * Also check to see if fullPageWrites was just turned on or there's a
-	 * running backup (which forces full-page writes); if we weren't already
-	 * doing full-page writes then go back and recompute.
-	 *
-	 * If we aren't doing full-page writes then RedoRecPtr doesn't actually
-	 * affect the contents of the XLOG record, so we'll update our local copy
-	 * but not force a recomputation.  (If doPageWrites was just turned off,
-	 * we could recompute the record without full pages, but we choose not to
-	 * bother.)
-	 */
-	if (RedoRecPtr != Insert->RedoRecPtr)
-	{
-		Assert(RedoRecPtr < Insert->RedoRecPtr);
-		RedoRecPtr = Insert->RedoRecPtr;
-	}
-	doPageWrites = (Insert->fullPageWrites || Insert->runningBackups > 0);
-
-	if (doPageWrites &&
-		(!prevDoPageWrites ||
-		 (fpw_lsn != InvalidXLogRecPtr && fpw_lsn <= RedoRecPtr)))
-	{
 		/*
-		 * Oops, some buffer now needs to be backed up that the caller didn't
+		 * Check to see if my copy of RedoRecPtr is out of date. If so, may
-		 * back up.  Start over.
+		 * have to go back and have the caller recompute everything. This can
+		 * only happen just after a checkpoint, so it's better to be slow in
+		 * this case and fast otherwise.
+		 *
+		 * Also check to see if fullPageWrites was just turned on or there's a
+		 * running backup (which forces full-page writes); if we weren't
+		 * already doing full-page writes then go back and recompute.
+		 *
+		 * If we aren't doing full-page writes then RedoRecPtr doesn't
+		 * actually affect the contents of the XLOG record, so we'll update
+		 * our local copy but not force a recomputation.  (If doPageWrites was
+		 * just turned off, we could recompute the record without full pages,
+		 * but we choose not to bother.)
 		 */
-		WALInsertLockRelease();
+		if (RedoRecPtr != Insert->RedoRecPtr)
-		END_CRIT_SECTION();
+		{
-		return InvalidXLogRecPtr;
+			Assert(RedoRecPtr < Insert->RedoRecPtr);
-	}
+			RedoRecPtr = Insert->RedoRecPtr;
+		}
+		doPageWrites = (Insert->fullPageWrites || Insert->runningBackups > 0);
 
-	/*
+		if (doPageWrites &&
-	 * Reserve space for the record in the WAL. This also sets the xl_prev
+			(!prevDoPageWrites ||
-	 * pointer.
+			 (fpw_lsn != InvalidXLogRecPtr && fpw_lsn <= RedoRecPtr)))
-	 */
+		{
-	if (isLogSwitch)
+			/*
-		inserted = ReserveXLogSwitch(&StartPos, &EndPos, &rechdr->xl_prev);
+			 * Oops, some buffer now needs to be backed up that the caller
-	else
+			 * didn't back up.  Start over.
-	{
+			 */
+			WALInsertLockRelease();
+			END_CRIT_SECTION();
+			return InvalidXLogRecPtr;
+		}
+
+		/*
+		 * Reserve space for the record in the WAL. This also sets the xl_prev
+		 * pointer.
+		 */
 		ReserveXLogInsertLocation(rechdr->xl_tot_len, &StartPos, &EndPos,
 								  &rechdr->xl_prev);
+
+		/* Normal records are always inserted. */
 		inserted = true;
 	}
+	else
+	{
+		/*
+		 * In order to insert an XLOG_SWITCH record, we need to hold all of
+		 * the WAL insertion locks, not just one, so that no one else can
+		 * begin inserting a record until we've figured out how much space
+		 * remains in the current WAL segment and claimed all of it.
+		 *
+		 * Nonetheless, this case is simpler than the normal cases handled
+		 * above, which must check for changes in doPageWrites and RedoRecPtr.
+		 * Those checks are only needed for records that can contain
+		 * full-pages images, and an XLOG_SWITCH record never does.
+		 */
+		Assert(fpw_lsn == InvalidXLogRecPtr);
+		WALInsertLockAcquireExclusive();
+		inserted = ReserveXLogSwitch(&StartPos, &EndPos, &rechdr->xl_prev);
+	}
 
 	if (inserted)
 	{
@@ -6722,7 +6737,9 @@ CreateCheckPoint(int flags)
 	{
 		do
 		{
+			pgstat_report_wait_start(WAIT_EVENT_CHECKPOINT_DELAY_START);
 			pg_usleep(10000L);	/* wait for 10 msec */
+			pgstat_report_wait_end();
 		} while (HaveVirtualXIDsDelayingChkpt(vxids, nvxids,
 											  DELAY_CHKPT_START));
 	}
@@ -6735,7 +6752,9 @@ CreateCheckPoint(int flags)
 	{
 		do
 		{
+			pgstat_report_wait_start(WAIT_EVENT_CHECKPOINT_DELAY_COMPLETE);
 			pg_usleep(10000L);	/* wait for 10 msec */
+			pgstat_report_wait_end();
 		} while (HaveVirtualXIDsDelayingChkpt(vxids, nvxids,
 											  DELAY_CHKPT_COMPLETE));
 	}

src/backend/executor/execPartition.c

@@ -2108,7 +2108,7 @@ 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 */
@@ -2117,34 +2117,39 @@ InitPartitionPruneContext(PartitionPruneContext *context,
 
 		Assert(list_length(step->exprs) <= partnatts);
 
-		keyno = 0;
+		for (keyno = 0; keyno < partnatts; keyno++)
-		foreach(lc2, step->exprs)
 		{
-			Expr	   *expr = (Expr *) lfirst(lc2);
+			if (bms_is_member(keyno, step->nullkeys))
+				continue;
 
-			/* not needed for Consts */
+			if (lc2 != NULL)
-			if (!IsA(expr, Const))
 			{
-				int			stateidx = PruneCxtStateIdx(partnatts,
+				Expr	   *expr = lfirst(lc2);
-														step->step.step_id,
-														keyno);
 
-				/*
+				/* not needed for Consts */
-				 * When planstate is NULL, pruning_steps is known not to
+				if (!IsA(expr, Const))
-				 * contain any expressions that depend on the parent plan.
+				{
-				 * Information of any available EXTERN parameters must be
+					int			stateidx = PruneCxtStateIdx(partnatts,
-				 * passed explicitly in that case, which the caller must have
+															step->step.step_id,
-				 * made available via econtext.
+															keyno);
-				 */
+
-				if (planstate == NULL)
+					/*
-					context->exprstates[stateidx] =
+					 * When planstate is NULL, pruning_steps is known not to
-						ExecInitExprWithParams(expr,
+					 * contain any expressions that depend on the parent plan.
-											   econtext->ecxt_param_list_info);
+					 * Information of any available EXTERN parameters must be
-				else
+					 * passed explicitly in that case, which the caller must
-					context->exprstates[stateidx] =
+					 * have made available via econtext.
-						ExecInitExpr(expr, context->planstate);
+					 */
+					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++;
 		}
 	}
 }

src/backend/partitioning/partprune.c

@@ -167,7 +167,6 @@ static List *get_steps_using_prefix(GeneratePruningStepsContext *context,
 									bool step_op_is_ne,
 									Expr *step_lastexpr,
 									Oid step_lastcmpfn,
-									int step_lastkeyno,
 									Bitmapset *step_nullkeys,
 									List *prefix);
 static List *get_steps_using_prefix_recurse(GeneratePruningStepsContext *context,
@@ -175,7 +174,6 @@ static List *get_steps_using_prefix_recurse(GeneratePruningStepsContext *context
 											bool step_op_is_ne,
 											Expr *step_lastexpr,
 											Oid step_lastcmpfn,
-											int step_lastkeyno,
 											Bitmapset *step_nullkeys,
 											List *prefix,
 											ListCell *start,
@@ -1531,7 +1529,6 @@ gen_prune_steps_from_opexps(GeneratePruningStepsContext *context,
 															  pc->op_is_ne,
 															  pc->expr,
 															  pc->cmpfn,
-															  0,
 															  NULL,
 															  NIL);
 							opsteps = list_concat(opsteps, pc_steps);
@@ -1657,7 +1654,6 @@ gen_prune_steps_from_opexps(GeneratePruningStepsContext *context,
 															  pc->op_is_ne,
 															  pc->expr,
 															  pc->cmpfn,
-															  pc->keyno,
 															  NULL,
 															  prefix);
 							opsteps = list_concat(opsteps, pc_steps);
@@ -1731,7 +1727,6 @@ gen_prune_steps_from_opexps(GeneratePruningStepsContext *context,
 												   false,
 												   pc->expr,
 												   pc->cmpfn,
-												   pc->keyno,
 												   nullkeys,
 												   prefix);
 						opsteps = list_concat(opsteps, pc_steps);
@@ -2350,25 +2345,31 @@ match_clause_to_partition_key(GeneratePruningStepsContext *context,
 
 /*
  * get_steps_using_prefix
- *		Generate list of PartitionPruneStepOp steps each consisting of given
+ *		Generate a list of PartitionPruneStepOps based on the given input.
- *		opstrategy
  *
- * To generate steps, step_lastexpr and step_lastcmpfn are appended to
+ * 'step_lastexpr' and 'step_lastcmpfn' are the Expr and comparison function
- * expressions and cmpfns, respectively, extracted from the clauses in
+ * belonging to the final partition key that we have a clause for.  'prefix'
- * 'prefix'.  Actually, since 'prefix' may contain multiple clauses for the
+ * is a list of PartClauseInfos for partition key numbers prior to the given
- * same partition key column, we must generate steps for various combinations
+ * 'step_lastexpr' and 'step_lastcmpfn'.  'prefix' may contain multiple
- * of the clauses of different keys.
+ * PartClauseInfos belonging to a single partition key.  We will generate a
+ * PartitionPruneStepOp for each combination of the given PartClauseInfos
+ * using, at most, one PartClauseInfo per partition key.
  *
- * For list/range partitioning, callers must ensure that step_nullkeys is
+ * For LIST and RANGE partitioned tables, callers must ensure that
- * NULL, and that prefix contains at least one clause for each of the
+ * step_nullkeys is NULL, and that prefix contains at least one clause for
- * partition keys earlier than one specified in step_lastkeyno if it's
+ * each of the partition keys prior to the key that 'step_lastexpr' and
- * greater than zero.  For hash partitioning, step_nullkeys is allowed to be
+ * 'step_lastcmpfn'belong to.
- * 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
+ * For HASH partitioned tables, callers must ensure that 'prefix' contains at
- * in ascending order of their partition key numbers.
+ * least one clause for each of the partition keys apart from the final key
+ * (the expr and comparison function for the final key are in 'step_lastexpr'
+ * and 'step_lastcmpfn').  A bit set in step_nullkeys can substitute clauses
+ * in the 'prefix' list for any given key.  If a bit is set in 'step_nullkeys'
+ * for a given key, then there must be no PartClauseInfo for that key in the
+ * 'prefix' list.
+ *
+ * For each of the above cases, callers must ensure that PartClauseInfos in
+ * 'prefix' are sorted in ascending order of keyno.
  */
 static List *
 get_steps_using_prefix(GeneratePruningStepsContext *context,
@@ -2376,14 +2377,17 @@ get_steps_using_prefix(GeneratePruningStepsContext *context,
 					   bool step_op_is_ne,
 					   Expr *step_lastexpr,
 					   Oid step_lastcmpfn,
-					   int step_lastkeyno,
 					   Bitmapset *step_nullkeys,
 					   List *prefix)
 {
+	/* step_nullkeys must be empty for RANGE and LIST partitioned tables */
 	Assert(step_nullkeys == NULL ||
 		   context->rel->part_scheme->strategy == PARTITION_STRATEGY_HASH);
 
-	/* Quick exit if there are no values to prefix with. */
+	/*
+	 * No recursive processing is required when 'prefix' is an empty list.
+	 * This occurs when there is only 1 partition key column.
+	 */
 	if (prefix == NIL)
 	{
 		PartitionPruneStep *step;
@@ -2397,13 +2401,12 @@ get_steps_using_prefix(GeneratePruningStepsContext *context,
 		return list_make1(step);
 	}
 
-	/* Recurse to generate steps for various combinations. */
+	/* Recurse to generate steps for every combination of clauses. */
 	return get_steps_using_prefix_recurse(context,
 										  step_opstrategy,
 										  step_op_is_ne,
 										  step_lastexpr,
 										  step_lastcmpfn,
-										  step_lastkeyno,
 										  step_nullkeys,
 										  prefix,
 										  list_head(prefix),
@@ -2412,13 +2415,17 @@ get_steps_using_prefix(GeneratePruningStepsContext *context,
 
 /*
  * get_steps_using_prefix_recurse
- *		Recursively generate combinations of clauses for different partition
+ *		Generate and return a list of PartitionPruneStepOps using the 'prefix'
- *		keys and start generating steps upon reaching clauses for the greatest
+ *		list of PartClauseInfos starting at the 'start' cell.
- *		column that is less than the one for which we're currently generating
- *		steps (that is, step_lastkeyno)
  *
- * 'prefix' is the list of PartClauseInfos.
+ * When 'prefix' contains multiple PartClauseInfos for a single partition key
- * 'start' is where we should start iterating for the current invocation.
+ * we create a PartitionPruneStepOp for each combination of duplicated
+ * PartClauseInfos.  The returned list will contain a PartitionPruneStepOp
+ * for each unique combination of input PartClauseInfos containing at most one
+ * PartClauseInfo per partition key.
+ *
+ * 'prefix' is the input list of PartClauseInfos sorted by keyno.
+ * 'start' marks the cell that searching the 'prefix' list should start from.
  * 'step_exprs' and 'step_cmpfns' each contains the expressions and cmpfns
  * we've generated so far from the clauses for the previous part keys.
  */
@@ -2428,7 +2435,6 @@ get_steps_using_prefix_recurse(GeneratePruningStepsContext *context,
 							   bool step_op_is_ne,
 							   Expr *step_lastexpr,
 							   Oid step_lastcmpfn,
-							   int step_lastkeyno,
 							   Bitmapset *step_nullkeys,
 							   List *prefix,
 							   ListCell *start,
@@ -2438,23 +2444,25 @@ get_steps_using_prefix_recurse(GeneratePruningStepsContext *context,
 	List	   *result = NIL;
 	ListCell   *lc;
 	int			cur_keyno;
+	int			final_keyno;
 
 	/* Actually, recursion would be limited by PARTITION_MAX_KEYS. */
 	check_stack_depth();
 
-	/* Check if we need to recurse. */
 	Assert(start != NULL);
 	cur_keyno = ((PartClauseInfo *) lfirst(start))->keyno;
-	if (cur_keyno < step_lastkeyno - 1)
+	final_keyno = ((PartClauseInfo *) llast(prefix))->keyno;
+
+	/* Check if we need to recurse. */
+	if (cur_keyno < final_keyno)
 	{
 		PartClauseInfo *pc;
 		ListCell   *next_start;
 
 		/*
-		 * For each clause with cur_keyno, add its expr and cmpfn to
+		 * Find the first PartClauseInfo belonging to the next partition key,
-		 * step_exprs and step_cmpfns, respectively, and recurse after setting
+		 * the next recursive call must start iteration of the prefix list
-		 * next_start to the ListCell of the first clause for the next
+		 * from that point.
-		 * partition key.
 		 */
 		for_each_cell(lc, prefix, start)
 		{
@@ -2463,8 +2471,15 @@ get_steps_using_prefix_recurse(GeneratePruningStepsContext *context,
 			if (pc->keyno > cur_keyno)
 				break;
 		}
+
+		/* record where to start iterating in the next recursive call */
 		next_start = lc;
 
+		/*
+		 * For each PartClauseInfo with keyno set to cur_keyno, add its expr
+		 * and cmpfn to step_exprs and step_cmpfns, respectively, and recurse
+		 * using 'next_start' as the starting point in the 'prefix' list.
+		 */
 		for_each_cell(lc, prefix, start)
 		{
 			List	   *moresteps;
@@ -2484,6 +2499,7 @@ get_steps_using_prefix_recurse(GeneratePruningStepsContext *context,
 			}
 			else
 			{
+				/* check the 'prefix' list is sorted correctly */
 				Assert(pc->keyno > cur_keyno);
 				break;
 			}
@@ -2493,7 +2509,6 @@ get_steps_using_prefix_recurse(GeneratePruningStepsContext *context,
 													   step_op_is_ne,
 													   step_lastexpr,
 													   step_lastcmpfn,
-													   step_lastkeyno,
 													   step_nullkeys,
 													   prefix,
 													   next_start,
@@ -2512,8 +2527,8 @@ get_steps_using_prefix_recurse(GeneratePruningStepsContext *context,
 		 * each clause with cur_keyno, which is all clauses from here onward
 		 * till the end of the list.  Note that for hash partitioning,
 		 * step_nullkeys is allowed to be non-empty, in which case step_exprs
-		 * would only contain expressions for the earlier partition keys that
+		 * would only contain expressions for the partition keys that are not
-		 * are not specified in step_nullkeys.
+		 * specified in step_nullkeys.
 		 */
 		Assert(list_length(step_exprs) == cur_keyno ||
 			   !bms_is_empty(step_nullkeys));

src/backend/utils/activity/wait_event_names.txt

@@ -97,6 +97,8 @@ BGWORKER_SHUTDOWN	"Waiting for background worker to shut down."
 BGWORKER_STARTUP	"Waiting for background worker to start up."
 BTREE_PAGE	"Waiting for the page number needed to continue a parallel B-tree scan to become available."
 BUFFER_IO	"Waiting for buffer I/O to complete."
+CHECKPOINT_DELAY_COMPLETE	"Waiting for a backend that blocks a checkpoint from completing."
+CHECKPOINT_DELAY_START	"Waiting for a backend that blocks a checkpoint from starting."
 CHECKPOINT_DONE	"Waiting for a checkpoint to complete."
 CHECKPOINT_START	"Waiting for a checkpoint to start."
 EXECUTE_GATHER	"Waiting for activity from a child process while executing a <literal>Gather</literal> plan node."

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);
@@ -4011,20 +4031,217 @@ explain (costs off) select * from rp_prefix_test3 where a >= 1 and b >= 1 and b
    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);
--- Test that get_steps_using_prefix() handles non-NULL step_nullkeys
-explain (costs off) select * from hp_prefix_test where a = 1 and b is null and c = 1 and d = 1;
-                         QUERY PLAN                          
--------------------------------------------------------------
- Seq Scan on hp_prefix_test_p1 hp_prefix_test
-   Filter: ((b IS NULL) AND (a = 1) AND (c = 1) AND (d = 1))
-(2 rows)
-
 drop table rp_prefix_test1;
 drop table rp_prefix_test2;
 drop table rp_prefix_test3;
+--
+-- Test that get_steps_using_prefix() handles IS NULL clauses correctly
+--
+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 8 partitions
+select 'create table hp_prefix_test_p' || x::text || ' partition of hp_prefix_test for values with (modulus 8, remainder ' || x::text || ');'
+from generate_Series(0,7) x;
+                                               ?column?                                               
+------------------------------------------------------------------------------------------------------
+ create table hp_prefix_test_p0 partition of hp_prefix_test for values with (modulus 8, remainder 0);
+ create table hp_prefix_test_p1 partition of hp_prefix_test for values with (modulus 8, remainder 1);
+ create table hp_prefix_test_p2 partition of hp_prefix_test for values with (modulus 8, remainder 2);
+ create table hp_prefix_test_p3 partition of hp_prefix_test for values with (modulus 8, remainder 3);
+ create table hp_prefix_test_p4 partition of hp_prefix_test for values with (modulus 8, remainder 4);
+ create table hp_prefix_test_p5 partition of hp_prefix_test for values with (modulus 8, remainder 5);
+ create table hp_prefix_test_p6 partition of hp_prefix_test for values with (modulus 8, remainder 6);
+ create table hp_prefix_test_p7 partition of hp_prefix_test for values with (modulus 8, remainder 7);
+(8 rows)
+
+\gexec
+create table hp_prefix_test_p0 partition of hp_prefix_test for values with (modulus 8, remainder 0);
+create table hp_prefix_test_p1 partition of hp_prefix_test for values with (modulus 8, remainder 1);
+create table hp_prefix_test_p2 partition of hp_prefix_test for values with (modulus 8, remainder 2);
+create table hp_prefix_test_p3 partition of hp_prefix_test for values with (modulus 8, remainder 3);
+create table hp_prefix_test_p4 partition of hp_prefix_test for values with (modulus 8, remainder 4);
+create table hp_prefix_test_p5 partition of hp_prefix_test for values with (modulus 8, remainder 5);
+create table hp_prefix_test_p6 partition of hp_prefix_test for values with (modulus 8, remainder 6);
+create table hp_prefix_test_p7 partition of hp_prefix_test for values with (modulus 8, remainder 7);
+-- insert 16 rows, one row for each test to perform.
+insert into hp_prefix_test
+select
+  case a when 0 then null else 1 end,
+  case b when 0 then null else 2 end,
+  case c when 0 then null else 3 end,
+  case d when 0 then null else 4 end
+from
+  generate_series(0,1) a,
+  generate_series(0,1) b,
+  generate_Series(0,1) c,
+  generate_Series(0,1) d;
+-- Ensure partition pruning works correctly for each combination of IS NULL
+-- and equality quals.  This may seem a little excessive, but there have been
+-- a number of bugs in this area over the years.  We make use of row only
+-- output to reduce the size of the expected results.
+\t on
+select
+  'explain (costs off) select tableoid::regclass,* from hp_prefix_test where ' ||
+  string_agg(c.colname || case when g.s & (1 << c.colpos) = 0 then ' is null' else ' = ' || (colpos+1)::text end, ' and ' order by c.colpos)
+from (values('a',0),('b',1),('c',2),('d',3)) c(colname, colpos), generate_Series(0,15) g(s)
+group by g.s
+order by g.s;
+ explain (costs off) select tableoid::regclass,* from hp_prefix_test where a is null and b is null and c is null and d is null
+ explain (costs off) select tableoid::regclass,* from hp_prefix_test where a = 1 and b is null and c is null and d is null
+ explain (costs off) select tableoid::regclass,* from hp_prefix_test where a is null and b = 2 and c is null and d is null
+ explain (costs off) select tableoid::regclass,* from hp_prefix_test where a = 1 and b = 2 and c is null and d is null
+ explain (costs off) select tableoid::regclass,* from hp_prefix_test where a is null and b is null and c = 3 and d is null
+ explain (costs off) select tableoid::regclass,* from hp_prefix_test where a = 1 and b is null and c = 3 and d is null
+ explain (costs off) select tableoid::regclass,* from hp_prefix_test where a is null and b = 2 and c = 3 and d is null
+ explain (costs off) select tableoid::regclass,* from hp_prefix_test where a = 1 and b = 2 and c = 3 and d is null
+ explain (costs off) select tableoid::regclass,* from hp_prefix_test where a is null and b is null and c is null and d = 4
+ explain (costs off) select tableoid::regclass,* from hp_prefix_test where a = 1 and b is null and c is null and d = 4
+ explain (costs off) select tableoid::regclass,* from hp_prefix_test where a is null and b = 2 and c is null and d = 4
+ explain (costs off) select tableoid::regclass,* from hp_prefix_test where a = 1 and b = 2 and c is null and d = 4
+ explain (costs off) select tableoid::regclass,* from hp_prefix_test where a is null and b is null and c = 3 and d = 4
+ explain (costs off) select tableoid::regclass,* from hp_prefix_test where a = 1 and b is null and c = 3 and d = 4
+ explain (costs off) select tableoid::regclass,* from hp_prefix_test where a is null and b = 2 and c = 3 and d = 4
+ explain (costs off) select tableoid::regclass,* from hp_prefix_test where a = 1 and b = 2 and c = 3 and d = 4
+
+\gexec
+explain (costs off) select tableoid::regclass,* from hp_prefix_test where a is null and b is null and c is null and d is null
+ Seq Scan on hp_prefix_test_p0 hp_prefix_test
+   Filter: ((a IS NULL) AND (b IS NULL) AND (c IS NULL) AND (d IS NULL))
+
+explain (costs off) select tableoid::regclass,* from hp_prefix_test where a = 1 and b is null and c is null and d is null
+ Seq Scan on hp_prefix_test_p1 hp_prefix_test
+   Filter: ((b IS NULL) AND (c IS NULL) AND (d IS NULL) AND (a = 1))
+
+explain (costs off) select tableoid::regclass,* from hp_prefix_test where a is null and b = 2 and c is null and d is null
+ Seq Scan on hp_prefix_test_p2 hp_prefix_test
+   Filter: ((a IS NULL) AND (c IS NULL) AND (d IS NULL) AND (b = 2))
+
+explain (costs off) select tableoid::regclass,* from hp_prefix_test where a = 1 and b = 2 and c is null and d is null
+ Seq Scan on hp_prefix_test_p4 hp_prefix_test
+   Filter: ((c IS NULL) AND (d IS NULL) AND (a = 1) AND (b = 2))
+
+explain (costs off) select tableoid::regclass,* from hp_prefix_test where a is null and b is null and c = 3 and d is null
+ Seq Scan on hp_prefix_test_p3 hp_prefix_test
+   Filter: ((a IS NULL) AND (b IS NULL) AND (d IS NULL) AND (c = 3))
+
+explain (costs off) select tableoid::regclass,* from hp_prefix_test where a = 1 and b is null and c = 3 and d is null
+ Seq Scan on hp_prefix_test_p7 hp_prefix_test
+   Filter: ((b IS NULL) AND (d IS NULL) AND (a = 1) AND (c = 3))
+
+explain (costs off) select tableoid::regclass,* from hp_prefix_test where a is null and b = 2 and c = 3 and d is null
+ Seq Scan on hp_prefix_test_p4 hp_prefix_test
+   Filter: ((a IS NULL) AND (d IS NULL) AND (b = 2) AND (c = 3))
+
+explain (costs off) select tableoid::regclass,* from hp_prefix_test where a = 1 and b = 2 and c = 3 and d is null
+ Seq Scan on hp_prefix_test_p5 hp_prefix_test
+   Filter: ((d IS NULL) AND (a = 1) AND (b = 2) AND (c = 3))
+
+explain (costs off) select tableoid::regclass,* from hp_prefix_test where a is null and b is null and c is null and d = 4
+ Seq Scan on hp_prefix_test_p4 hp_prefix_test
+   Filter: ((a IS NULL) AND (b IS NULL) AND (c IS NULL) AND (d = 4))
+
+explain (costs off) select tableoid::regclass,* from hp_prefix_test where a = 1 and b is null and c is null and d = 4
+ Seq Scan on hp_prefix_test_p6 hp_prefix_test
+   Filter: ((b IS NULL) AND (c IS NULL) AND (a = 1) AND (d = 4))
+
+explain (costs off) select tableoid::regclass,* from hp_prefix_test where a is null and b = 2 and c is null and d = 4
+ Seq Scan on hp_prefix_test_p5 hp_prefix_test
+   Filter: ((a IS NULL) AND (c IS NULL) AND (b = 2) AND (d = 4))
+
+explain (costs off) select tableoid::regclass,* from hp_prefix_test where a = 1 and b = 2 and c is null and d = 4
+ Seq Scan on hp_prefix_test_p6 hp_prefix_test
+   Filter: ((c IS NULL) AND (a = 1) AND (b = 2) AND (d = 4))
+
+explain (costs off) select tableoid::regclass,* from hp_prefix_test where a is null and b is null and c = 3 and d = 4
+ Seq Scan on hp_prefix_test_p4 hp_prefix_test
+   Filter: ((a IS NULL) AND (b IS NULL) AND (c = 3) AND (d = 4))
+
+explain (costs off) select tableoid::regclass,* from hp_prefix_test where a = 1 and b is null and c = 3 and d = 4
+ Seq Scan on hp_prefix_test_p5 hp_prefix_test
+   Filter: ((b IS NULL) AND (a = 1) AND (c = 3) AND (d = 4))
+
+explain (costs off) select tableoid::regclass,* from hp_prefix_test where a is null and b = 2 and c = 3 and d = 4
+ Seq Scan on hp_prefix_test_p6 hp_prefix_test
+   Filter: ((a IS NULL) AND (b = 2) AND (c = 3) AND (d = 4))
+
+explain (costs off) select tableoid::regclass,* from hp_prefix_test where a = 1 and b = 2 and c = 3 and d = 4
+ Seq Scan on hp_prefix_test_p4 hp_prefix_test
+   Filter: ((a = 1) AND (b = 2) AND (c = 3) AND (d = 4))
+
+-- And ensure we get exactly 1 row from each. Again, all 16 possible combinations.
+select
+  'select tableoid::regclass,* from hp_prefix_test where ' ||
+  string_agg(c.colname || case when g.s & (1 << c.colpos) = 0 then ' is null' else ' = ' || (colpos+1)::text end, ' and ' order by c.colpos)
+from (values('a',0),('b',1),('c',2),('d',3)) c(colname, colpos), generate_Series(0,15) g(s)
+group by g.s
+order by g.s;
+ select tableoid::regclass,* from hp_prefix_test where a is null and b is null and c is null and d is null
+ select tableoid::regclass,* from hp_prefix_test where a = 1 and b is null and c is null and d is null
+ select tableoid::regclass,* from hp_prefix_test where a is null and b = 2 and c is null and d is null
+ select tableoid::regclass,* from hp_prefix_test where a = 1 and b = 2 and c is null and d is null
+ select tableoid::regclass,* from hp_prefix_test where a is null and b is null and c = 3 and d is null
+ select tableoid::regclass,* from hp_prefix_test where a = 1 and b is null and c = 3 and d is null
+ select tableoid::regclass,* from hp_prefix_test where a is null and b = 2 and c = 3 and d is null
+ select tableoid::regclass,* from hp_prefix_test where a = 1 and b = 2 and c = 3 and d is null
+ select tableoid::regclass,* from hp_prefix_test where a is null and b is null and c is null and d = 4
+ select tableoid::regclass,* from hp_prefix_test where a = 1 and b is null and c is null and d = 4
+ select tableoid::regclass,* from hp_prefix_test where a is null and b = 2 and c is null and d = 4
+ select tableoid::regclass,* from hp_prefix_test where a = 1 and b = 2 and c is null and d = 4
+ select tableoid::regclass,* from hp_prefix_test where a is null and b is null and c = 3 and d = 4
+ select tableoid::regclass,* from hp_prefix_test where a = 1 and b is null and c = 3 and d = 4
+ select tableoid::regclass,* from hp_prefix_test where a is null and b = 2 and c = 3 and d = 4
+ select tableoid::regclass,* from hp_prefix_test where a = 1 and b = 2 and c = 3 and d = 4
+
+\gexec
+select tableoid::regclass,* from hp_prefix_test where a is null and b is null and c is null and d is null
+ hp_prefix_test_p0 |   |   |   |  
+
+select tableoid::regclass,* from hp_prefix_test where a = 1 and b is null and c is null and d is null
+ hp_prefix_test_p1 | 1 |   |   |  
+
+select tableoid::regclass,* from hp_prefix_test where a is null and b = 2 and c is null and d is null
+ hp_prefix_test_p2 |   | 2 |   |  
+
+select tableoid::regclass,* from hp_prefix_test where a = 1 and b = 2 and c is null and d is null
+ hp_prefix_test_p4 | 1 | 2 |   |  
+
+select tableoid::regclass,* from hp_prefix_test where a is null and b is null and c = 3 and d is null
+ hp_prefix_test_p3 |   |   | 3 |  
+
+select tableoid::regclass,* from hp_prefix_test where a = 1 and b is null and c = 3 and d is null
+ hp_prefix_test_p7 | 1 |   | 3 |  
+
+select tableoid::regclass,* from hp_prefix_test where a is null and b = 2 and c = 3 and d is null
+ hp_prefix_test_p4 |   | 2 | 3 |  
+
+select tableoid::regclass,* from hp_prefix_test where a = 1 and b = 2 and c = 3 and d is null
+ hp_prefix_test_p5 | 1 | 2 | 3 |  
+
+select tableoid::regclass,* from hp_prefix_test where a is null and b is null and c is null and d = 4
+ hp_prefix_test_p4 |   |   |   | 4
+
+select tableoid::regclass,* from hp_prefix_test where a = 1 and b is null and c is null and d = 4
+ hp_prefix_test_p6 | 1 |   |   | 4
+
+select tableoid::regclass,* from hp_prefix_test where a is null and b = 2 and c is null and d = 4
+ hp_prefix_test_p5 |   | 2 |   | 4
+
+select tableoid::regclass,* from hp_prefix_test where a = 1 and b = 2 and c is null and d = 4
+ hp_prefix_test_p6 | 1 | 2 |   | 4
+
+select tableoid::regclass,* from hp_prefix_test where a is null and b is null and c = 3 and d = 4
+ hp_prefix_test_p4 |   |   | 3 | 4
+
+select tableoid::regclass,* from hp_prefix_test where a = 1 and b is null and c = 3 and d = 4
+ hp_prefix_test_p5 | 1 |   | 3 | 4
+
+select tableoid::regclass,* from hp_prefix_test where a is null and b = 2 and c = 3 and d = 4
+ hp_prefix_test_p6 |   | 2 | 3 | 4
+
+select tableoid::regclass,* from hp_prefix_test where a = 1 and b = 2 and c = 3 and d = 4
+ hp_prefix_test_p4 | 1 | 2 | 3 | 4
+
+\t off
 drop table hp_prefix_test;
 --
 -- Check that gen_partprune_steps() detects self-contradiction from clauses

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);
@@ -1182,16 +1199,57 @@ explain (costs off) select * from rp_prefix_test3 where a >= 1 and b >= 1 and b
 -- 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);
-
--- Test that get_steps_using_prefix() handles non-NULL step_nullkeys
-explain (costs off) select * from hp_prefix_test where a = 1 and b is null and c = 1 and d = 1;
-
 drop table rp_prefix_test1;
 drop table rp_prefix_test2;
 drop table rp_prefix_test3;
+
+--
+-- Test that get_steps_using_prefix() handles IS NULL clauses correctly
+--
+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 8 partitions
+select 'create table hp_prefix_test_p' || x::text || ' partition of hp_prefix_test for values with (modulus 8, remainder ' || x::text || ');'
+from generate_Series(0,7) x;
+\gexec
+
+-- insert 16 rows, one row for each test to perform.
+insert into hp_prefix_test
+select
+  case a when 0 then null else 1 end,
+  case b when 0 then null else 2 end,
+  case c when 0 then null else 3 end,
+  case d when 0 then null else 4 end
+from
+  generate_series(0,1) a,
+  generate_series(0,1) b,
+  generate_Series(0,1) c,
+  generate_Series(0,1) d;
+
+-- Ensure partition pruning works correctly for each combination of IS NULL
+-- and equality quals.  This may seem a little excessive, but there have been
+-- a number of bugs in this area over the years.  We make use of row only
+-- output to reduce the size of the expected results.
+\t on
+select
+  'explain (costs off) select tableoid::regclass,* from hp_prefix_test where ' ||
+  string_agg(c.colname || case when g.s & (1 << c.colpos) = 0 then ' is null' else ' = ' || (colpos+1)::text end, ' and ' order by c.colpos)
+from (values('a',0),('b',1),('c',2),('d',3)) c(colname, colpos), generate_Series(0,15) g(s)
+group by g.s
+order by g.s;
+\gexec
+
+-- And ensure we get exactly 1 row from each. Again, all 16 possible combinations.
+select
+  'select tableoid::regclass,* from hp_prefix_test where ' ||
+  string_agg(c.colname || case when g.s & (1 << c.colpos) = 0 then ' is null' else ' = ' || (colpos+1)::text end, ' and ' order by c.colpos)
+from (values('a',0),('b',1),('c',2),('d',3)) c(colname, colpos), generate_Series(0,15) g(s)
+group by g.s
+order by g.s;
+\gexec
+\t off
+
 drop table hp_prefix_test;
 
 --