Re: Parallel Bitmap Heap Scan reports per-worker stats in EXPLAIN ANALYZE

Hi! Thank you for your work on this issue!

Your patch required a little revision. I did this and attached the patch.

Also, I think you should add some clarification to the comments about
printing 'exact' and 'loosy' pages in show_hashagg_info function, which
you get from planstate->stats, whereas previously it was output only
from planstate. Perhaps it is enough to mention this in the comment to
the commit.

I mean this place:

diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 926d70afaf..02251994c6 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -3467,26 +3467,57 @@ show_hashagg_info(AggState *aggstate,
ExplainState *es)
 static void
 show_tidbitmap_info(BitmapHeapScanState *planstate, ExplainState *es)
 {
+    Assert(es->analyze);
+
     if (es->format != EXPLAIN_FORMAT_TEXT)
     {
         ExplainPropertyInteger("Exact Heap Blocks", NULL,
-                               planstate->exact_pages, es);
+                               planstate->stats.exact_pages, es);
         ExplainPropertyInteger("Lossy Heap Blocks", NULL,
-                               planstate->lossy_pages, es);
+                               planstate->stats.lossy_pages, es);
     }
     else
     {
-        if (planstate->exact_pages > 0 || planstate->lossy_pages > 0)
+        if (planstate->stats.exact_pages > 0 ||
planstate->stats.lossy_pages > 0)
         {
             ExplainIndentText(es);
             appendStringInfoString(es->str, "Heap Blocks:");
-            if (planstate->exact_pages > 0)
-                appendStringInfo(es->str, " exact=%ld",
planstate->exact_pages);
-            if (planstate->lossy_pages > 0)
-                appendStringInfo(es->str, " lossy=%ld",
planstate->lossy_pages);
+            if (planstate->stats.exact_pages > 0)
+                appendStringInfo(es->str, " exact=%ld",
planstate->stats.exact_pages);
+            if (planstate->stats.lossy_pages > 0)
+                appendStringInfo(es->str, " lossy=%ld",
planstate->stats.lossy_pages);
             appendStringInfoChar(es->str, '\n');
         }
     }
+
+    if (planstate->pstate != NULL)
+    {
+        for (int n = 0; n < planstate->sinstrument->num_workers; n++)
+        {
+            BitmapHeapScanInstrumentation *si =
&planstate->sinstrument->sinstrument[n];
+
+            if (si->exact_pages == 0 && si->lossy_pages == 0)
+                continue;
+
+            if (es->workers_state)
+                ExplainOpenWorker(n, es);
+
+            if (es->format == EXPLAIN_FORMAT_TEXT)
+            {
+                ExplainIndentText(es);
+                appendStringInfo(es->str, "Heap Blocks: exact=%ld
lossy=%ld\n",
+                         si->exact_pages, si->lossy_pages);
+            }
+            else
+            {
+                ExplainPropertyInteger("Exact Heap Blocks", NULL,
si->exact_pages, es);
+                ExplainPropertyInteger("Lossy Heap Blocks", NULL,
si->lossy_pages, es);
+            }
+
+            if (es->workers_state)
+                ExplainCloseWorker(n, es);
+        }
+    }
 }

I suggest some code refactoring (diff.diff.no-cfbot file) that allows
you to improve your code.

--
Regards,
Alena Rybakina
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company