Re: BUG #15032: Segmentation fault when running a particular query

Guo Xiang Tan <gxtan1990@gmail.com> writes:
>> Unsurprisingly, the given info is not enough to reproduce the crash.

> We could only reproduce this on our production PostgreSQL cluster.

Since the problem occurs during EvalPlanQual, it'd only manifest when
the update touched a concurrently-updated row, which is why it's hard
to reproduce if you aren't deliberately trying to trigger it.  But
I've been able to reproduce a crash at the same spot, and have made
a test case using the isolationtester infrastructure (attached).

I'll look into an actual fix tomorrow.

            regards, tom lane

diff --git a/src/test/isolation/specs/eval-plan-qual.spec b/src/test/isolation/specs/eval-plan-qual.spec
index 7ff6f6b..53a32e6 100644
*** a/src/test/isolation/specs/eval-plan-qual.spec
--- b/src/test/isolation/specs/eval-plan-qual.spec
*************** setup
*** 21,33 ****
   CREATE TABLE table_b (id integer, value text);
   INSERT INTO table_a VALUES (1, 'tableAValue');
   INSERT INTO table_b VALUES (1, 'tableBValue');
  }

  teardown
  {
   DROP TABLE accounts;
   DROP TABLE p CASCADE;
!  DROP TABLE table_a, table_b;
  }

  session "s1"
--- 21,36 ----
   CREATE TABLE table_b (id integer, value text);
   INSERT INTO table_a VALUES (1, 'tableAValue');
   INSERT INTO table_b VALUES (1, 'tableBValue');
+
+  CREATE TABLE jointest AS SELECT generate_series(1,10) AS id, 0 AS data;
+  CREATE INDEX ON jointest(id);
  }

  teardown
  {
   DROP TABLE accounts;
   DROP TABLE p CASCADE;
!  DROP TABLE table_a, table_b, jointest;
  }

  session "s1"
*************** step "updateforss"    {
*** 78,83 ****
--- 81,96 ----
      UPDATE table_b SET value = 'newTableBValue' WHERE id = 1;
  }

+ # these tests exercise mark/restore during EPQ recheck, cf bug #15032
+
+ step "selectjoinforupdate"    {
+     set enable_hashjoin to 0;
+     set enable_seqscan to 0;
+     explain (costs off)
+     select * from jointest a join jointest b on a.id=b.id for update;
+     select * from jointest a join jointest b on a.id=b.id for update;
+ }
+

  session "s2"
  setup        { BEGIN ISOLATION LEVEL READ COMMITTED; }
*************** step "readforss"    {
*** 104,109 ****
--- 117,123 ----
      WHERE ta.id = 1 FOR UPDATE OF ta;
  }
  step "wrtwcte"    { UPDATE table_a SET value = 'tableAValue2' WHERE id = 1; }
+ step "wrjt"    { UPDATE jointest SET data = 42 WHERE id = 7; }
  step "c2"    { COMMIT; }

  session "s3"
*************** permutation "wx2" "partiallock" "c2" "c1
*** 135,137 ****
--- 149,152 ----
  permutation "wx2" "lockwithvalues" "c2" "c1" "read"
  permutation "updateforss" "readforss" "c1" "c2"
  permutation "wrtwcte" "readwcte" "c1" "c2"
+ permutation "wrjt" "selectjoinforupdate" "c2" "c1"