Trigger information for auto_explain.

Hello,

Now explain can show trigger statistics (from when?).

=# create table t (a int, b int);
=# create or replace function hoge() returns trigger as 'begin new.b = new.a; return new; end;' language plpgsql;
=# create trigger ins_hoge before insert or update on t for each row execute procedure hoge();

Explain analyze shows trigger information.

=# explain analyze insert into t (select a from generate_series(0, 100) a);
| QUERY PLAN
|----------------------------------------------------------------
| Insert on t (cost=0.00..10.00 rows=1000 width=4) (actual time=2.712.....
| -> Function Scan on generate_series a (cost=0.00..10.00 rows=1000 width=4)
| (actual time=0.047..0.147 rows=101 loops=1)
| Trigger ins_hoge: time=1.881 calls=101
| Total runtime: 3.009 ms

On the other hand, auto_explain doesn't.

=# load auto_explain;
=# set auto_explain.log_min_duration = 0;
=# set auto_explain.log_analyze = 'yes';
=# insert into t (select a from generate_series(0, 100) a);
|LOG: duration: 2.871 ms plan:
| Query Text: insert into t (select a from generate_series(0, 100) a);
| Insert on t (cost=0.00..10.00 rows=1000 width=4)
| -> Function Scan on generate_series a (cost=0.00..10.00 ...

auto_explain will show trigger infos with this patch like this.

=# set auto_explain.log_triggers = 'yes';
=# insert into t (select a from generate_series(0, 100) a);
| LOG: duration: 2.098 ms plan:
| Query Text: insert into t (select a from generate_series(0, 100) a);
| Insert on t (cost=0.00..10.00 rows=1000 width=4) (actual time=2.097..2.097 rows=0 loops=1)
| -> Function Scan on generate_series a (cost=0.00..10.00 rows=1000 width=4) (actual time=0.044..0.123 rows=101 loops=1)
| Trigger ins_hoge: time=1.452 calls=101

This patch consists of two parts,

0001_expose_explain_triggers_v1_20140114.patch

Expose the code to print out trigger information currently
hidden in ExplainOnePlan().

0002_auto_explain_triggers_v1_20140114.patch

Enable auto_explain to output trigger information.

Documentation will be added later..

regards,

--
Kyotaro Horiguchi
NTT Open Source Software Center