On Tue, Sep 14, 2021 at 10:44 AM Tom Lane <t...@sss.pgh.pa.us> wrote:
> Rajkumar Raghuwanshi <rajkumar.raghuwan...@enterprisedb.com> writes: > > I am getting "ERROR: subplan "SubPlan 1" was not initialized" error with > > below test case. > > > CREATE TABLE tbl ( c1 int, c2 int, c3 int ) PARTITION BY LIST (c1); > > create table tbl_null PARTITION OF tbl FOR VALUES IN (null); > > create table tbl_def PARTITION OF tbl DEFAULT; > > insert into tbl values (8800,0,0); > > insert into tbl values (1891,1,1); > > insert into tbl values (3420,2,0); > > insert into tbl values (9850,3,0); > > insert into tbl values (7164,4,4); > > analyze tbl; > > explain (costs off) select count(*) from tbl t1 where (exists(select 1 > from > > tbl t2 where t2.c1 = t1.c2) or c3 < 0); > > > postgres=# explain (costs off) select count(*) from tbl t1 where > > (exists(select 1 from tbl t2 where t2.c1 = t1.c2) or c3 < 0); > > ERROR: subplan "SubPlan 1" was not initialized > > Nice example. This is failing since 41efb8340. It happens because > we copy the AlternativeSubPlan for the EXISTS into the scan clauses > for each of t1's partitions. At setrefs.c time, when > fix_alternative_subplan() looks at the first of these > AlternativeSubPlans, it decides it likes the first subplan better, > so it deletes SubPlan 2 from the root->glob->subplans list. But when > it comes to the next copy (which is attached to a partition with a > different number of rows), it likes the second subplan better, so it > deletes SubPlan 1 from the root->glob->subplans list. Now we have > SubPlan nodes in the tree with no referents in the global list of > subplans, so kaboom. > > The easiest fix would just be to not try to delete unreferenced > subplans. The error goes away if I remove the "lfirst(lc2) = NULL" > statements from fix_alternative_subplan(). However, this is a bit > annoying since then we will still pay the cost of initializing > subplans that (in most cases) will never be used. I'm going to > look into how painful it is to have setrefs.c remove unused subplans > only at the end, after it's seen all the AlternativeSubPlans. > > regards, tom lane > > > Hi, In the fix, isUsedSubplan is used to tell whether any given subplan is used. Since only one subplan is used, I wonder if the array can be replaced by specifying the subplan is used. Cheers
