4 files changed, 56 insertions, 0 deletions

diff --git a/src/backend/access/gist/gistget.c b/src/backend/access/gist/gistget.c
index 122dc38db56..5a4dea89ac5 100644
--- a/src/backend/access/gist/gistget.c
+++ b/src/backend/access/gist/gistget.c
@@ -375,6 +375,7 @@ gistScanPage(IndexScanDesc scan, GISTSearchItem *pageItem, double *myDistances,
 	}
 
 	so->nPageData = so->curPageData = 0;
+	scan->xs_hitup = NULL;		/* might point into pageDataCxt */
 	if (so->pageDataCxt)
 		MemoryContextReset(so->pageDataCxt);
 
@@ -642,6 +643,7 @@ gistgettuple(IndexScanDesc scan, ScanDirection dir)
 
 		so->firstCall = false;
 		so->curPageData = so->nPageData = 0;
+		scan->xs_hitup = NULL;
 		if (so->pageDataCxt)
 			MemoryContextReset(so->pageDataCxt);
 
@@ -766,6 +768,7 @@ gistgetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
 
 	/* Begin the scan by processing the root page */
 	so->curPageData = so->nPageData = 0;
+	scan->xs_hitup = NULL;
 	if (so->pageDataCxt)
 		MemoryContextReset(so->pageDataCxt);
 
diff --git a/src/backend/access/gist/gistscan.c b/src/backend/access/gist/gistscan.c
index 81ff8fc8b6e..058544e2ae2 100644
--- a/src/backend/access/gist/gistscan.c
+++ b/src/backend/access/gist/gistscan.c
@@ -313,6 +313,9 @@ gistrescan(IndexScanDesc scan, ScanKey key, int nkeys,
 		if (!first_time)
 			pfree(fn_extras);
 	}
+
+	/* any previous xs_hitup will have been pfree'd in context resets above */
+	scan->xs_hitup = NULL;
 }
 
 void
diff --git a/src/test/regress/expected/gist.out b/src/test/regress/expected/gist.out
index c7181b0397e..91f99981409 100644
--- a/src/test/regress/expected/gist.out
+++ b/src/test/regress/expected/gist.out
@@ -114,6 +114,40 @@ order by point(0.101, 0.101) <-> p;
  (0.5,0.5)
 (11 rows)
 
+-- Check case with multiple rescans (bug #14641)
+explain (costs off)
+select p from
+  (values (box(point(0,0), point(0.5,0.5))),
+          (box(point(0.5,0.5), point(0.75,0.75))),
+          (box(point(0.8,0.8), point(1.0,1.0)))) as v(bb)
+cross join lateral
+  (select p from gist_tbl where p <@ bb order by p <-> bb[0] limit 2) ss;
+                             QUERY PLAN                             
+--------------------------------------------------------------------
+ Nested Loop
+   ->  Values Scan on "*VALUES*"
+   ->  Limit
+         ->  Index Only Scan using gist_tbl_point_index on gist_tbl
+               Index Cond: (p <@ "*VALUES*".column1)
+               Order By: (p <-> ("*VALUES*".column1)[0])
+(6 rows)
+
+select p from
+  (values (box(point(0,0), point(0.5,0.5))),
+          (box(point(0.5,0.5), point(0.75,0.75))),
+          (box(point(0.8,0.8), point(1.0,1.0)))) as v(bb)
+cross join lateral
+  (select p from gist_tbl where p <@ bb order by p <-> bb[0] limit 2) ss;
+      p      
+-------------
+ (0.5,0.5)
+ (0.45,0.45)
+ (0.75,0.75)
+ (0.7,0.7)
+ (1,1)
+ (0.95,0.95)
+(6 rows)
+
 drop index gist_tbl_point_index;
 -- Test index-only scan with box opclass
 create index gist_tbl_box_index on gist_tbl using gist (b);
diff --git a/src/test/regress/sql/gist.sql b/src/test/regress/sql/gist.sql
index 9d4ff1e97e9..49126fd466d 100644
--- a/src/test/regress/sql/gist.sql
+++ b/src/test/regress/sql/gist.sql
@@ -69,6 +69,22 @@ order by point(0.101, 0.101) <-> p;
 select p from gist_tbl where p <@ box(point(0,0), point(0.5, 0.5))
 order by point(0.101, 0.101) <-> p;
 
+-- Check case with multiple rescans (bug #14641)
+explain (costs off)
+select p from
+  (values (box(point(0,0), point(0.5,0.5))),
+          (box(point(0.5,0.5), point(0.75,0.75))),
+          (box(point(0.8,0.8), point(1.0,1.0)))) as v(bb)
+cross join lateral
+  (select p from gist_tbl where p <@ bb order by p <-> bb[0] limit 2) ss;
+
+select p from
+  (values (box(point(0,0), point(0.5,0.5))),
+          (box(point(0.5,0.5), point(0.75,0.75))),
+          (box(point(0.8,0.8), point(1.0,1.0)))) as v(bb)
+cross join lateral
+  (select p from gist_tbl where p <@ bb order by p <-> bb[0] limit 2) ss;
+
 drop index gist_tbl_point_index;
 
 -- Test index-only scan with box opclass