Fix parallel sort, broken by the balanced merge patch.

The code for initializing the tapes on each merge iteration was skipped
in a parallel worker. I put the !WORKER(state) check in wrong place while
rebasing the patch.

That caused failures in the index build in 'multiple-row-versions'
isolation test, in multiple buildfarm members. On my laptop it was easier
to reproduce by building an index on a larger table, so that you got a
parallel sort more reliably.

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 0c5c574cbd3d1e4ef6379befc3d28c4c89151cd7..9e93908c6576d8698a614e46b6a0a880580093a1 100644 (file)
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -2923,7 +2923,7 @@ mergeruns(Tuplesortstate *state)
         * Rewind all the output tapes, and make them inputs for the next
         * pass.
         */
-       if (state->nInputRuns == 0 && !WORKER(state))
+       if (state->nInputRuns == 0)
        {
            int64       input_buffer_size;
 
@@ -2975,7 +2975,8 @@ mergeruns(Tuplesortstate *state)
             * sorted tape, we can stop at this point and do the final merge
             * on-the-fly.
             */
-           if (!state->randomAccess && state->nInputRuns <= state->nInputTapes)
+           if (!state->randomAccess && state->nInputRuns <= state->nInputTapes
+               && !WORKER(state))
            {
                /* Tell logtape.c we won't be writing anymore */
                LogicalTapeSetForgetFreeSpace(state->tapeset);