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

diff --git a/src/backend/executor/execAmi.c b/src/backend/executor/execAmi.c
index f1636a5b883cf8947cf27cd044760d42f0f28164..1ab68f5cc91cb5565decb9fdab002f29e2cb4be0 100644 (file)
--- 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 646e577272eb57d3628a872fb58ab892e872abb5..0c75b39d2be7faad23edf49fb961c8fd7c577fec 100644 (file)
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -249,6 +249,8 @@ 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 f9b4067b1e767f7c3abffecb3ab52a9e8b4d147d..3c7436cf27e4be520a7b6bc1b0defb525c5316fe 100644 (file)
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -674,6 +674,7 @@ 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;