Don't use_physical_tlist for an IOS with non-returnable columns.

createplan.c tries to save a runtime projection step by specifying
a scan plan node's output as being exactly the table's columns, or
index's columns in the case of an index-only scan, if there is not a
reason to do otherwise.  This logic did not previously pay attention
to whether an index's columns are returnable.  That worked, sort of
accidentally, until commit 9a3ddeb51 taught setrefs.c to reject plans
that try to read a non-returnable column.  I have no desire to loosen
setrefs.c's new check, so instead adjust use_physical_tlist() to not
try to optimize this way when there are non-returnable column(s).

Per report from Ryan Kelly.  Like the previous patch, back-patch
to all supported branches.

Discussion: https://postgr.es/m/CAHUie24ddN+pDNw7fkhNrjrwAX=fXXfGZZEHhRuofV_N_ftaSg@mail.gmail.com

diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 29e5f99193c79a7a395fc6818bef4281a7352d59..5e6259f6a855bf7d78a2d00eee79e0267f931cb4 100644 (file)
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -833,6 +833,22 @@ use_physical_tlist(PlannerInfo *root, Path *path, int flags)
            return false;
    }
 
+   /*
+    * For an index-only scan, the "physical tlist" is the index's indextlist.
+    * We can only return that without a projection if all the index's columns
+    * are returnable.
+    */
+   if (path->pathtype == T_IndexOnlyScan)
+   {
+       IndexOptInfo *indexinfo = ((IndexPath *) path)->indexinfo;
+
+       for (i = 0; i < indexinfo->ncolumns; i++)
+       {
+           if (!indexinfo->canreturn[i])
+               return false;
+       }
+   }
+
    /*
     * Also, can't do it if CP_LABEL_TLIST is specified and path is requested
     * to emit any sort/group columns that are not simple Vars.  (If they are

diff --git a/src/test/regress/expected/gist.out b/src/test/regress/expected/gist.out
index 374873b6836a0f1b9443e748c9491a6dd6496a3f..d0260a0481d0a2b5a8538ad0db544577439aec1d 100644 (file)
--- a/src/test/regress/expected/gist.out
+++ b/src/test/regress/expected/gist.out
@@ -265,6 +265,22 @@ select p from gist_tbl where circle(p,1) @> circle(point(0,0),0.95);
  (0,0)
 (1 row)
 
+-- Also check that use_physical_tlist doesn't trigger in such cases.
+explain (verbose, costs off)
+select count(*) from gist_tbl;
+                             QUERY PLAN                              
+---------------------------------------------------------------------
+ Aggregate
+   Output: count(*)
+   ->  Index Only Scan using gist_tbl_multi_index on public.gist_tbl
+(3 rows)
+
+select count(*) from gist_tbl;
+ count 
+-------
+ 10001
+(1 row)
+
 -- This case isn't supported, but it should at least EXPLAIN correctly.
 explain (verbose, costs off)
 select p from gist_tbl order by circle(p,1) <-> point(0,0) limit 1;

diff --git a/src/test/regress/sql/gist.sql b/src/test/regress/sql/gist.sql
index 487791bc812b078d7715ac280e0d71bcc16c5fc6..011f15bca0156aec51cd0d9f0f803eb8d7b77ca2 100644 (file)
--- a/src/test/regress/sql/gist.sql
+++ b/src/test/regress/sql/gist.sql
@@ -131,6 +131,11 @@ explain (verbose, costs off)
 select p from gist_tbl where circle(p,1) @> circle(point(0,0),0.95);
 select p from gist_tbl where circle(p,1) @> circle(point(0,0),0.95);
 
+-- Also check that use_physical_tlist doesn't trigger in such cases.
+explain (verbose, costs off)
+select count(*) from gist_tbl;
+select count(*) from gist_tbl;
+
 -- This case isn't supported, but it should at least EXPLAIN correctly.
 explain (verbose, costs off)
 select p from gist_tbl order by circle(p,1) <-> point(0,0) limit 1;