postgres.git / summary / log / commit / refs

commit    018e7d98dc157265efc4121e2b5971c0a2afcbe1
Author:   Andrew Gierth <rhodiumtoad@postgresql.org>
Date:     Tue Nov 24 20:58:32 2020 +0000
First released in: 14.0, 9.5.25, 9.6.21, 10.16, 11.11, 12.6, 13.2

    Properly check index mark/restore in ExecSupportsMarkRestore.
    
    Previously this code assumed that all IndexScan nodes supported
    mark/restore, which is not true since it depends on optional index AM
    support functions. This could lead to errors about missing support
    functions in rare edge cases of mergejoins with no sort keys, where an
    unordered non-btree index scan was placed on the inner path without a
    protecting Materialize node. (Normally, the fact that merge join
    requires ordered input would avoid this error.)
    
    Backpatch all the way since this bug is ancient.
    
    Per report from Eugen Konkov on irc.
    
    Discussion: https://postgr.es/m/87o8jn50be.fsf@news-spur.riddles.org.uk


 src/backend/executor/execAmi.c       | 5 +++++
 src/backend/optimizer/util/plancat.c | 2 ++
 src/include/nodes/relation.h         | 1 +
 3 files changed, 8 insertions(+)

diff --git a/src/backend/executor/execAmi.c b/src/backend/executor/execAmi.c
index 9e784219786..b01ef446734 100644
--- a/src/backend/executor/execAmi.c
+++ b/src/backend/executor/execAmi.c
@@ -413,6 +413,11 @@ ExecSupportsMarkRestore(Path *pathnode)
 	{
 		case T_IndexScan:
 		case T_IndexOnlyScan:
+			/*
+			 * Not all index types support mark/restore.
+			 */
+			return castNode(IndexPath, pathnode)->indexinfo->amcanmarkpos;
+
 		case T_Material:
 		case T_Sort:
 			return true;
diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index d99d1393fb4..c8bab50e89c 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -275,6 +275,8 @@ get_relation_info(PlannerInfo *root, Oid relationObjectId, bool inhparent,
 			info->amcanparallel = amroutine->amcanparallel;
 			info->amhasgettuple = (amroutine->amgettuple != NULL);
 			info->amhasgetbitmap = (amroutine->amgetbitmap != NULL);
+			info->amcanmarkpos = (amroutine->ammarkpos != NULL &&
+								  amroutine->amrestrpos != NULL);
 			info->amcostestimate = amroutine->amcostestimate;
 			Assert(info->amcostestimate != NULL);
 
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index ffeb3eb1fee..098116b0d8b 100644
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -809,6 +809,7 @@ typedef struct IndexOptInfo
 	bool		amhasgettuple;	/* does AM have amgettuple interface? */
 	bool		amhasgetbitmap; /* does AM have amgetbitmap interface? */
 	bool		amcanparallel;	/* does AM support parallel scan? */
+	bool		amcanmarkpos;	/* does AM support mark/restore? */
 	/* Rather than include amapi.h here, we declare amcostestimate like this */
 	void		(*amcostestimate) ();	/* AM's cost estimator */
 } IndexOptInfo;


[parent: 57b5d8484c8a]