Fix EXPLAIN for compressed DML

EXPLAIN ANALYZE for compressed DML would error out with `bogus varno` error because we would modify the original expressions of the plan that were still referenced in nodes instead of adjusting copies and using those copies in our internal scans.
timescale · Oct 18, 2023 · 8f3bb0b · 8f3bb0b
1 parent 5f5f519
commit 8f3bb0b
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Showing 4 changed files with 70 additions and 4 deletions.
diff --git a/.unreleased/pr_6210 b/.unreleased/pr_6210
@@ -0,0 +1 @@
+Fixes: #6210 Fix EXPLAIN ANALYZE for compressed DML
diff --git a/tsl/src/compression/compression.c b/tsl/src/compression/compression.c
@@ -2756,9 +2756,7 @@ fill_predicate_context(Chunk *ch, List *predicates, List **filters, List **index
 	ListCell *lc;
 	foreach (lc, predicates)
 	{
-		Node *node = lfirst(lc);
-		if (node == NULL)
-			continue;
+		Node *node = copyObject(lfirst(lc));
 
 		Var *var;
 		char *column_name;
@@ -3367,7 +3365,6 @@ decompress_chunk_walker(PlanState *ps, struct decompress_chunk_context *ctx)
 		case T_TidScanState:
 		case T_TidRangeScanState:
 		{
-			/* We copy so we can always just free the predicates */
 			predicates = list_copy(ps->plan->qual);
 			needs_decompression = true;
 			break;

diff --git a/tsl/test/shared/expected/decompress_tracking.out b/tsl/test/shared/expected/decompress_tracking.out
@@ -45,6 +45,22 @@ QUERY PLAN
                      ->  Seq Scan on _hyper_X_X_chunk decompress_tracking_2 (actual rows=20 loops=1)
 (10 rows)
 
+BEGIN; :EXPLAIN_ANALYZE UPDATE decompress_tracking SET value = value + 3 WHERE device = 'd2'; ROLLBACK;
+QUERY PLAN
+ Custom Scan (HypertableModify) (actual rows=0 loops=1)
+   Batches decompressed: 2
+   Tuples decompressed: 20
+   ->  Update on decompress_tracking (actual rows=0 loops=1)
+         Update on _hyper_X_X_chunk decompress_tracking_1
+         Update on _hyper_X_X_chunk decompress_tracking_2
+         ->  Result (actual rows=20 loops=1)
+               ->  Append (actual rows=20 loops=1)
+                     ->  Seq Scan on _hyper_X_X_chunk decompress_tracking_1 (actual rows=15 loops=1)
+                           Filter: (device = 'd2'::text)
+                     ->  Seq Scan on _hyper_X_X_chunk decompress_tracking_2 (actual rows=5 loops=1)
+                           Filter: (device = 'd2'::text)
+(12 rows)
+
 BEGIN; :EXPLAIN_ANALYZE DELETE FROM decompress_tracking; ROLLBACK;
 QUERY PLAN
  Custom Scan (HypertableModify) (actual rows=0 loops=1)
@@ -58,6 +74,21 @@ QUERY PLAN
                ->  Seq Scan on _hyper_X_X_chunk decompress_tracking_2 (actual rows=20 loops=1)
 (9 rows)
 
+BEGIN; :EXPLAIN_ANALYZE DELETE FROM decompress_tracking WHERE device = 'd3'; ROLLBACK;
+QUERY PLAN
+ Custom Scan (HypertableModify) (actual rows=0 loops=1)
+   Batches decompressed: 2
+   Tuples decompressed: 30
+   ->  Delete on decompress_tracking (actual rows=0 loops=1)
+         Delete on _hyper_X_X_chunk decompress_tracking_1
+         Delete on _hyper_X_X_chunk decompress_tracking_2
+         ->  Append (actual rows=30 loops=1)
+               ->  Seq Scan on _hyper_X_X_chunk decompress_tracking_1 (actual rows=15 loops=1)
+                     Filter: (device = 'd3'::text)
+               ->  Seq Scan on _hyper_X_X_chunk decompress_tracking_2 (actual rows=15 loops=1)
+                     Filter: (device = 'd3'::text)
+(11 rows)
+
 BEGIN; :EXPLAIN_ANALYZE INSERT INTO decompress_tracking SELECT '2020-01-01 1:30','d1',random(); ROLLBACK;
 QUERY PLAN
  Custom Scan (HypertableModify) (actual rows=0 loops=1)
@@ -97,4 +128,34 @@ QUERY PLAN
                ->  Values Scan on "*VALUES*" (actual rows=2 loops=1)
 (6 rows)
 
+-- test prepared statements EXPLAIN still works after execution
+SET plan_cache_mode TO force_generic_plan;
+PREPARE p1 AS UPDATE decompress_tracking SET value = value + 3 WHERE device = 'd1';
+BEGIN; EXPLAIN EXECUTE p1; EXECUTE p1; EXPLAIN EXECUTE p1; ROLLBACK;
+QUERY PLAN
+ Custom Scan (HypertableModify)  (cost=0.00..70.83 rows=433 width=18)
+   ->  Update on decompress_tracking  (cost=0.00..70.83 rows=433 width=18)
+         Update on _hyper_X_X_chunk decompress_tracking_1
+         Update on _hyper_X_X_chunk decompress_tracking_2
+         ->  Result  (cost=0.00..70.83 rows=433 width=18)
+               ->  Append  (cost=0.00..65.42 rows=433 width=18)
+                     ->  Seq Scan on _hyper_X_X_chunk decompress_tracking_1  (cost=0.00..31.62 rows=432 width=18)
+                           Filter: (device = 'd1'::text)
+                     ->  Seq Scan on _hyper_X_X_chunk decompress_tracking_2  (cost=0.00..31.62 rows=1 width=18)
+                           Filter: (device = 'd1'::text)
+(10 rows)
+
+QUERY PLAN
+ Custom Scan (HypertableModify)  (cost=0.00..70.83 rows=433 width=18)
+   ->  Update on decompress_tracking  (cost=0.00..70.83 rows=433 width=18)
+         Update on _hyper_X_X_chunk decompress_tracking_1
+         Update on _hyper_X_X_chunk decompress_tracking_2
+         ->  Result  (cost=0.00..70.83 rows=433 width=18)
+               ->  Append  (cost=0.00..65.42 rows=433 width=18)
+                     ->  Seq Scan on _hyper_X_X_chunk decompress_tracking_1  (cost=0.00..31.62 rows=432 width=18)
+                           Filter: (device = 'd1'::text)
+                     ->  Seq Scan on _hyper_X_X_chunk decompress_tracking_2  (cost=0.00..31.62 rows=1 width=18)
+                           Filter: (device = 'd1'::text)
+(10 rows)
+
 DROP TABLE decompress_tracking;
diff --git a/tsl/test/shared/sql/decompress_tracking.sql b/tsl/test/shared/sql/decompress_tracking.sql
@@ -19,10 +19,17 @@ SELECT count(compress_chunk(ch)) FROM show_chunks('decompress_tracking') ch;
 :EXPLAIN UPDATE decompress_tracking SET value = value + 3;
 
 BEGIN; :EXPLAIN_ANALYZE UPDATE decompress_tracking SET value = value + 3; ROLLBACK;
+BEGIN; :EXPLAIN_ANALYZE UPDATE decompress_tracking SET value = value + 3 WHERE device = 'd2'; ROLLBACK;
 BEGIN; :EXPLAIN_ANALYZE DELETE FROM decompress_tracking; ROLLBACK;
+BEGIN; :EXPLAIN_ANALYZE DELETE FROM decompress_tracking WHERE device = 'd3'; ROLLBACK;
 BEGIN; :EXPLAIN_ANALYZE INSERT INTO decompress_tracking SELECT '2020-01-01 1:30','d1',random(); ROLLBACK;
 BEGIN; :EXPLAIN_ANALYZE INSERT INTO decompress_tracking SELECT '2020-01-01','d2',random(); ROLLBACK;
 BEGIN; :EXPLAIN_ANALYZE INSERT INTO decompress_tracking SELECT '2020-01-01','d4',random(); ROLLBACK;
 BEGIN; :EXPLAIN_ANALYZE INSERT INTO decompress_tracking (VALUES ('2020-01-01 1:30','d1',random()),('2020-01-01 1:30','d2',random())); ROLLBACK;
 
+-- test prepared statements EXPLAIN still works after execution
+SET plan_cache_mode TO force_generic_plan;
+PREPARE p1 AS UPDATE decompress_tracking SET value = value + 3 WHERE device = 'd1';
+BEGIN; EXPLAIN EXECUTE p1; EXECUTE p1; EXPLAIN EXECUTE p1; ROLLBACK;
+
 DROP TABLE decompress_tracking;
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		Fixes: #6210 Fix EXPLAIN ANALYZE for compressed DML