Hi Amit,
On 07/07/2018 01:08 AM, Amit Kapila wrote:
On Wed, Mar 14, 2018 at 8:58 PM, Jesper Pedersen
Parallel Append's ntuples is 1, but given nloops is 3 you end up with the
slightly confusing "(actual ... *rows=0* loops=3)".
The number of rows displayed is total_rows / loops due to which you
are seeing these numbers. This behavior is the same for all parallel
nodes, nothing specific to Parallel Append.
Thanks !
Maybe something like the attached patch for the documentation is needed.
Best regards,
Jesper
diff --git a/doc/src/sgml/parallel.sgml b/doc/src/sgml/parallel.sgml
index dd7834a763..ea941e4fb4 100644
--- a/doc/src/sgml/parallel.sgml
+++ b/doc/src/sgml/parallel.sgml
@@ -423,7 +423,9 @@ EXPLAIN SELECT * FROM pgbench_accounts WHERE filler LIKE '%x%';
VERBOSE)</literal> to display per-worker statistics for each plan node.
This may be useful in determining whether the work is being evenly
distributed between all plan nodes and more generally in understanding the
- performance characteristics of the plan.
+ performance characteristics of the plan. Note, that the parallel nodes
+ may report zero rows returned due internal calculations when one or more
+ rows are actually being returned.
</para>
</sect2>
