On Sun, 24 Feb 2019 at 15:24, Tom Lane <t...@sss.pgh.pa.us> wrote:
> I haven't attempted any performance measurements on this, but at
> least in principle it should speed things up a bit, especially
> for complex test cases involving longer Lists.  I don't have any
> very suitable test cases at hand, anyway.

I've not yet looked at the code, but I thought I'd give this a quick benchmark.

Using the attached patch (as text file so as not to upset the CFbot),
which basically just measures and logs the time taken to run
pg_plan_query. Using this, I ran make installcheck 3 times unpatched
and same again with the patch. I pulled the results of each run into a
spreadsheet and took the average of each of the 3 runs then took the
sum of the total average planning time over the 20334 individual
results.

Results patched atop of 067786cea:

Total average time unpatched:  0.739808667 seconds
Total average time patched:  0.748144333 seconds.

Surprisingly it took 1.13% longer.  I did these tests on an AWS
md5.large instance.

If required, I can send the entire spreadsheet. It's about 750 KB.

-- 
 David Rowley                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 8b4d94c9a1..437256a35f 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -21,6 +21,7 @@
 
 #include <fcntl.h>
 #include <limits.h>
+#include <time.h>
 #include <signal.h>
 #include <unistd.h>
 #include <sys/socket.h>
@@ -965,7 +966,15 @@ pg_plan_queries(List *querytrees, int cursorOptions, 
ParamListInfo boundParams)
                }
                else
                {
+                       clock_t start, end;
+
+                       start = clock();
+
                        stmt = pg_plan_query(query, cursorOptions, boundParams);
+
+                       end = clock();
+
+                       elog(LOG, "PlannerTime: %f", (double)(end - start) / 
CLOCKS_PER_SEC);
                }
 
                stmt_list = lappend(stmt_list, stmt);

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