Re: mark/restore failures on unsorted merge joins - Mailing list pgsql-hackers

>>>>> "Tom" == Tom Lane <tgl@sss.pgh.pa.us> writes:

 Tom> Oh, sorry, I misread your comment to be that you wanted to add a
 Tom> field to IndexAmRoutine. You're right, the real issue here is that
 Tom> ExecSupportsMarkRestore lacks any convenient access to the needed
 Tom> info, and we need to add a bool to IndexOptInfo to fix that.

 Tom> I don't see any compelling reason why you couldn't add the field
 Tom> at the end in the back branches; that's what we usually do to
 Tom> avoid ABI breaks. Although actually (counts fields...) it looks
 Tom> like there's at least one pad byte after amcanparallel, so you
 Tom> could add a bool there without any ABI consequence, resulting in a
 Tom> reasonably natural field order in all branches.

I guess that's close enough; this should suffice then.

-- 
Andrew (irc:RhodiumToad)

diff --git a/src/backend/executor/execAmi.c b/src/backend/executor/execAmi.c
index e2154ba86a..0c10f1d35c 100644
--- a/src/backend/executor/execAmi.c
+++ b/src/backend/executor/execAmi.c
@@ -417,6 +417,11 @@ 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 52c01eb86b..3e94256d34 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -284,6 +284,8 @@ get_relation_info(PlannerInfo *root, Oid relationObjectId, bool inhparent,
             info->amhasgettuple = (amroutine->amgettuple != NULL);
             info->amhasgetbitmap = amroutine->amgetbitmap != NULL &&
                 relation->rd_tableam->scan_bitmap_next_block != NULL;
+            info->amcanmarkpos = (amroutine->ammarkpos != NULL &&
+                                  amroutine->amrestrpos != NULL);
             info->amcostestimate = amroutine->amcostestimate;
             Assert(info->amcostestimate != NULL);
 
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index abe6f570e3..5a10c1855d 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -864,6 +864,7 @@ 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 */
 };