Fix "force_parallel_mode = regress" to work with ANALYZE + VERBOSE.

force_parallel_mode = regress is supposed to force use of a Gather
node without having any impact on EXPLAIN output.  But it failed to
accomplish that if both ANALYZE and VERBOSE are given, because that
enables per-worker output data that you wouldn't see if the Gather
hadn't been inserted.  Improve the logic so that we suppress the
per-worker data too.

This allows putting the new test case added by commit 5935917ce
back into the originally intended form (cf. 776a2c887, 22864f6e0).
We can also get rid of a kluge in subselect.sql, which previously
had to clean up after force_parallel_mode's failure to do what it
said on the tin.

Discussion: https://postgr.es/m/18445.1576177309@sss.pgh.pa.us

diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 7ae5a42e455c3bb285d35a80d07d4a7c215be40f..949fefa23ae7235fb79aa8833a3a5a1cb1e331ca 100644 (file)
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -695,13 +695,19 @@ ExplainPrintPlan(ExplainState *es, QueryDesc *queryDesc)
 
    /*
     * Sometimes we mark a Gather node as "invisible", which means that it's
-    * not displayed in EXPLAIN output.  The purpose of this is to allow
+    * not to be displayed in EXPLAIN output.  The purpose of this is to allow
     * running regression tests with force_parallel_mode=regress to get the
     * same results as running the same tests with force_parallel_mode=off.
+    * Such marking is currently only supported on a Gather at the top of the
+    * plan.  We skip that node, and we must also hide per-worker detail data
+    * further down in the plan tree.
     */
    ps = queryDesc->planstate;
    if (IsA(ps, GatherState) &&((Gather *) ps->plan)->invisible)
+   {
        ps = outerPlanState(ps);
+       es->hide_workers = true;
+   }
    ExplainNode(ps, NIL, NULL, NULL, es);
 
    /*
@@ -806,6 +812,10 @@ ExplainPrintJIT(ExplainState *es, int jit_flags,
    if (!ji || ji->created_functions == 0)
        return;
 
+   /* don't print per-worker info if we're supposed to hide that */
+   if (for_workers && es->hide_workers)
+       return;
+
    /* calculate total time */
    INSTR_TIME_SET_ZERO(total_time);
    INSTR_TIME_ADD(total_time, ji->generation_counter);
@@ -1877,7 +1887,8 @@ ExplainNode(PlanState *planstate, List *ancestors,
        show_buffer_usage(es, &planstate->instrument->bufusage);
 
    /* Show worker detail */
-   if (es->analyze && es->verbose && planstate->worker_instrument)
+   if (es->analyze && es->verbose && !es->hide_workers &&
+       planstate->worker_instrument)
    {
        WorkerInstrumentation *w = planstate->worker_instrument;
        bool        opened_group = false;
@@ -2574,6 +2585,12 @@ show_sort_info(SortState *sortstate, ExplainState *es)
        }
    }
 
+   /*
+    * You might think we should just skip this stanza entirely when
+    * es->hide_workers is true, but then we'd get no sort-method output at
+    * all.  We have to make it look like worker 0's data is top-level data.
+    * Currently, we only bother with that for text-format output.
+    */
    if (sortstate->shared_info != NULL)
    {
        int         n;
@@ -2596,9 +2613,11 @@ show_sort_info(SortState *sortstate, ExplainState *es)
            if (es->format == EXPLAIN_FORMAT_TEXT)
            {
                appendStringInfoSpaces(es->str, es->indent * 2);
+               if (n > 0 || !es->hide_workers)
+                   appendStringInfo(es->str, "Worker %d:  ", n);
                appendStringInfo(es->str,
-                                "Worker %d:  Sort Method: %s  %s: %ldkB\n",
-                                n, sortMethod, spaceType, spaceUsed);
+                                "Sort Method: %s  %s: %ldkB\n",
+                                sortMethod, spaceType, spaceUsed);
            }
            else
            {

diff --git a/src/include/commands/explain.h b/src/include/commands/explain.h
index 8639891c1643fff047584b5bda5251c81b40dd9c..e4f4b704dfa7b05dc90f39e4a155988a09a4a951 100644 (file)
--- a/src/include/commands/explain.h
+++ b/src/include/commands/explain.h
@@ -46,6 +46,7 @@ typedef struct ExplainState
    List       *rtable_names;   /* alias names for RTEs */
    List       *deparse_cxt;    /* context list for deparsing expressions */
    Bitmapset  *printed_subplans;   /* ids of SubPlans we've printed */
+   bool        hide_workers;   /* set if we find an invisible Gather */
 } ExplainState;
 
 /* Hook for plugins to get control in ExplainOneQuery() */

diff --git a/src/test/regress/expected/partition_prune.out b/src/test/regress/expected/partition_prune.out
index 8219abc813eaf1d4c01c8c5695203e837cd7e0b3..424d51d5216d54cce4a0f73c780bc49eee42ea31 100644 (file)
--- a/src/test/regress/expected/partition_prune.out
+++ b/src/test/regress/expected/partition_prune.out
@@ -3163,12 +3163,12 @@ execute mt_q1(35);
 deallocate mt_q1;
 prepare mt_q2 (int) as select * from ma_test where a >= $1 order by b limit 1;
 -- Ensure output list looks sane when the MergeAppend has no subplans.
-explain (verbose, costs off) execute mt_q2 (35);
-           QUERY PLAN           
---------------------------------
- Limit
+explain (analyze, verbose, costs off, summary off, timing off) execute mt_q2 (35);
+                 QUERY PLAN                 
+--------------------------------------------
+ Limit (actual rows=0 loops=1)
    Output: ma_test.a, ma_test.b
-   ->  Merge Append
+   ->  Merge Append (actual rows=0 loops=1)
          Sort Key: ma_test.b
          Subplans Removed: 3
 (5 rows)

diff --git a/src/test/regress/expected/subselect.out b/src/test/regress/expected/subselect.out
index ee9c5db0d5123e7c53c5c21dc92366fa71485ede..547686166a6523d967db2d6c15a01af0c03c36f0 100644 (file)
--- a/src/test/regress/expected/subselect.out
+++ b/src/test/regress/expected/subselect.out
@@ -1166,8 +1166,6 @@ begin
         select * from (select pk,c2 from sq_limit order by c1,pk) as x limit 3
     loop
         ln := regexp_replace(ln, 'Memory: \S*',  'Memory: xxx');
-        -- this case might occur if force_parallel_mode is on:
-        ln := regexp_replace(ln, 'Worker 0:  Sort Method',  'Sort Method');
         return next ln;
     end loop;
 end;

diff --git a/src/test/regress/sql/partition_prune.sql b/src/test/regress/sql/partition_prune.sql
index 61ef6e637e49db32795cb99077f40590614f38d6..d9daba3af301a25f9ee0dcc6d96c73e76ad0bb06 100644 (file)
--- a/src/test/regress/sql/partition_prune.sql
+++ b/src/test/regress/sql/partition_prune.sql
@@ -841,7 +841,7 @@ deallocate mt_q1;
 prepare mt_q2 (int) as select * from ma_test where a >= $1 order by b limit 1;
 
 -- Ensure output list looks sane when the MergeAppend has no subplans.
-explain (verbose, costs off) execute mt_q2 (35);
+explain (analyze, verbose, costs off, summary off, timing off) execute mt_q2 (35);
 
 deallocate mt_q2;
 

diff --git a/src/test/regress/sql/subselect.sql b/src/test/regress/sql/subselect.sql
index 20c4f99c9c43e1fa426b1dfa03b2fc96e6f9af25..3e119ce127430b6b770ff0252ae084acb7e69731 100644 (file)
--- a/src/test/regress/sql/subselect.sql
+++ b/src/test/regress/sql/subselect.sql
@@ -631,8 +631,6 @@ begin
         select * from (select pk,c2 from sq_limit order by c1,pk) as x limit 3
     loop
         ln := regexp_replace(ln, 'Memory: \S*',  'Memory: xxx');
-        -- this case might occur if force_parallel_mode is on:
-        ln := regexp_replace(ln, 'Worker 0:  Sort Method',  'Sort Method');
         return next ln;
     end loop;
 end;