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Insert temporary debugging output in regression tests.

2019年5月21日 16:23:16 +0000 (12:23 -0400)

2019年5月21日 16:23:21 +0000 (12:23 -0400)

We're seeing occasional instability in the plans generated for
parallel queries on the "a_star" table hierarchy. This suggests
that something is changing the planner's stats for those tables,
but that should not be happening within a regression test run.
To try to gather some information about what's happening, insert
additional queries to check the basic page/tuple counts for these
tables, as well as whether any vacuums or analyzes have happened
on them. (We expect that only the database-wide VACUUM in
sanity_check.sql will have touched them.)

I added the probes not only in select_parallel.sql itself, but
also in stats.sql, bearing in mind that the stats collector's
lag may prevent the initial query from reporting current truth.
If any extra vacuum/analyze has happened, the recheck in stats.sql
definitely ought to see it.

This commit can be reverted once we figure out what's going on.

Per suggestion from David Rowley, though I changed the queries around.

Discussion: https://postgr.es/m/CA+hUKG+0CxrKRWRMf5ymN3gm+BECHna2B-q1w8onKBep4HasUw@mail.gmail.com

src/test/regress/expected/select_parallel.out patch | blob | blame | history

src/test/regress/expected/stats.out patch | blob | blame | history

src/test/regress/sql/select_parallel.sql patch | blob | blame | history

src/test/regress/sql/stats.sql patch | blob | blame | history

diff --git a/src/test/regress/expected/select_parallel.out b/src/test/regress/expected/select_parallel.out

index 0eca76cb41e78300ef41069d92f660606b10aab0..9775cc898ce818dc33d2ee352dcf9da338f14a5c 100644 (file)

--- a/src/test/regress/expected/select_parallel.out

+++ b/src/test/regress/expected/select_parallel.out

@@ -89,6 +89,33 @@ select round(avg(aa)), sum(aa) from a_star a3;

14 | 355

(1 row)

+-- Temporary hack to investigate whether extra vacuum/analyze is happening

+select relname, relpages, reltuples

+from pg_class

+where relname like '__star' order by relname;

+ relname | relpages | reltuples

+---------+----------+-----------

+ a_star | 1 | 3

+ b_star | 1 | 4

+ c_star | 1 | 4

+ d_star | 1 | 16

+ e_star | 1 | 7

+ f_star | 1 | 16

+(6 rows)

+select relname, vacuum_count, analyze_count, autovacuum_count, autoanalyze_count

+from pg_stat_all_tables

+where relname like '__star' order by relname;

+ relname | vacuum_count | analyze_count | autovacuum_count | autoanalyze_count

+---------+--------------+---------------+------------------+-------------------

+ a_star | 1 | 0 | 0 | 0

+ b_star | 1 | 0 | 0 | 0

+ c_star | 1 | 0 | 0 | 0

+ d_star | 1 | 0 | 0 | 0

+ e_star | 1 | 0 | 0 | 0

+ f_star | 1 | 0 | 0 | 0

+(6 rows)

-- Disable Parallel Append

alter table a_star reset (parallel_workers);

alter table b_star reset (parallel_workers);

diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out

index b01e58b98cb15137708e30d872cc97b8504defac..61fbf7e41eaede12e6da4065ec46c16b7388e5fd 100644 (file)

--- a/src/test/regress/expected/stats.out

+++ b/src/test/regress/expected/stats.out

@@ -199,6 +199,33 @@ FROM prevstats AS pr;

(1 row)

+-- Temporary hack to investigate whether extra vacuum/analyze is happening

+select relname, relpages, reltuples

+from pg_class

+where relname like '__star' order by relname;

+ relname | relpages | reltuples

+---------+----------+-----------

+ a_star | 1 | 3

+ b_star | 1 | 4

+ c_star | 1 | 4

+ d_star | 1 | 16

+ e_star | 1 | 7

+ f_star | 1 | 16

+(6 rows)

+select relname, vacuum_count, analyze_count, autovacuum_count, autoanalyze_count

+from pg_stat_all_tables

+where relname like '__star' order by relname;

+ relname | vacuum_count | analyze_count | autovacuum_count | autoanalyze_count

+---------+--------------+---------------+------------------+-------------------

+ a_star | 1 | 0 | 0 | 0

+ b_star | 1 | 0 | 0 | 0

+ c_star | 1 | 0 | 0 | 0

+ d_star | 1 | 0 | 0 | 0

+ e_star | 1 | 0 | 0 | 0

+ f_star | 1 | 0 | 0 | 0

+(6 rows)

DROP TABLE trunc_stats_test, trunc_stats_test1, trunc_stats_test2, trunc_stats_test3, trunc_stats_test4;

DROP TABLE prevstats;

-- End of Stats Test

diff --git a/src/test/regress/sql/select_parallel.sql b/src/test/regress/sql/select_parallel.sql

index 03c056b8b771f64c7c02d6157412f6708636c485..f96812b550627d4f5908e8f4b7123de1b36725d9 100644 (file)

--- a/src/test/regress/sql/select_parallel.sql

+++ b/src/test/regress/sql/select_parallel.sql

@@ -36,6 +36,14 @@ explain (costs off)

select round(avg(aa)), sum(aa) from a_star;

select round(avg(aa)), sum(aa) from a_star a3;

+-- Temporary hack to investigate whether extra vacuum/analyze is happening

+select relname, relpages, reltuples

+from pg_class

+where relname like '__star' order by relname;

+select relname, vacuum_count, analyze_count, autovacuum_count, autoanalyze_count

+from pg_stat_all_tables

+where relname like '__star' order by relname;

-- Disable Parallel Append

alter table a_star reset (parallel_workers);

alter table b_star reset (parallel_workers);

diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql

index feaaee6326e2f6e0102151aaa53dc9fca70b2f7a..9defd4b7a9791dbb340842776162a92c6f5fd363 100644 (file)

--- a/src/test/regress/sql/stats.sql

+++ b/src/test/regress/sql/stats.sql

@@ -174,6 +174,14 @@ SELECT st.heap_blks_read + st.heap_blks_hit >= pr.heap_blks + cl.relpages,

SELECT pr.snap_ts < pg_stat_get_snapshot_timestamp() as snapshot_newer

FROM prevstats AS pr;

+-- Temporary hack to investigate whether extra vacuum/analyze is happening

+select relname, relpages, reltuples

+from pg_class

+where relname like '__star' order by relname;

+select relname, vacuum_count, analyze_count, autovacuum_count, autoanalyze_count

+from pg_stat_all_tables

+where relname like '__star' order by relname;

DROP TABLE trunc_stats_test, trunc_stats_test1, trunc_stats_test2, trunc_stats_test3, trunc_stats_test4;

DROP TABLE prevstats;

-- End of Stats Test

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