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Track statement entry timestamp in contrib/pg_stat_statements

This patch adds 'stats_since' and 'minmax_stats_since' columns to the
pg_stat_statements view and pg_stat_statements() function.  The new min/max
reset mode for the pg_stat_stetments_reset() function is controlled by the
parameter minmax_only.

'stat_since' column is populated with the current timestamp when a new
statement is added to the pg_stat_statements hashtable.  It provides clean
information about statistics collection time intervals for each statement.
Besides it can be used by sampling solutions to detect situations when a
statement was evicted and stored again between samples.

Such a sampling solution could derive any pg_stat_statements statistic values
for an interval between two samples with the exception of all min/max
statistics. To address this issue this patch adds the ability to reset
min/max statistics independently of the statement reset using the new
minmax_only parameter of the pg_stat_statements_reset(userid oid, dbid oid,
queryid bigint, minmax_only boolean) function. The timestamp of such reset
is stored in the minmax_stats_since field for each statement.
pg_stat_statements_reset() function now returns the timestamp of a reset as the
result.

Discussion: https://postgr.es/m/flat/72e80e7b160a6eb189df9ef6f068cce3765d37f8.camel%40moonset.ru
Author: Andrei Zubkov
Reviewed-by: Julien Rouhaud, Hayato Kuroda, Yuki Seino, Chengxi Sun
Reviewed-by: Anton Melnikov, Darren Rush, Michael Paquier, Sergei Kornilov
Reviewed-by: Alena Rybakina, Andrei Lepikhov
This commit is contained in:
Alexander Korotkov
2023-11-27 02:51:18 +02:00
parent 6ab1dbd26b
commit dc9f8a7983
9 changed files with 511 additions and 96 deletions

View File

@ -250,59 +250,61 @@ SELECT count(*) > 0 AS has_data FROM pg_stat_statements;
t
(1 row)
-- New views for pg_stat_statements in 1.11
-- New functions and views for pg_stat_statements in 1.11
AlTER EXTENSION pg_stat_statements UPDATE TO '1.11';
\d pg_stat_statements
View "public.pg_stat_statements"
Column | Type | Collation | Nullable | Default
------------------------+------------------+-----------+----------+---------
userid | oid | | |
dbid | oid | | |
toplevel | boolean | | |
queryid | bigint | | |
query | text | | |
plans | bigint | | |
total_plan_time | double precision | | |
min_plan_time | double precision | | |
max_plan_time | double precision | | |
mean_plan_time | double precision | | |
stddev_plan_time | double precision | | |
calls | bigint | | |
total_exec_time | double precision | | |
min_exec_time | double precision | | |
max_exec_time | double precision | | |
mean_exec_time | double precision | | |
stddev_exec_time | double precision | | |
rows | bigint | | |
shared_blks_hit | bigint | | |
shared_blks_read | bigint | | |
shared_blks_dirtied | bigint | | |
shared_blks_written | bigint | | |
local_blks_hit | bigint | | |
local_blks_read | bigint | | |
local_blks_dirtied | bigint | | |
local_blks_written | bigint | | |
temp_blks_read | bigint | | |
temp_blks_written | bigint | | |
shared_blk_read_time | double precision | | |
shared_blk_write_time | double precision | | |
local_blk_read_time | double precision | | |
local_blk_write_time | double precision | | |
temp_blk_read_time | double precision | | |
temp_blk_write_time | double precision | | |
wal_records | bigint | | |
wal_fpi | bigint | | |
wal_bytes | numeric | | |
jit_functions | bigint | | |
jit_generation_time | double precision | | |
jit_inlining_count | bigint | | |
jit_inlining_time | double precision | | |
jit_optimization_count | bigint | | |
jit_optimization_time | double precision | | |
jit_emission_count | bigint | | |
jit_emission_time | double precision | | |
jit_deform_count | bigint | | |
jit_deform_time | double precision | | |
View "public.pg_stat_statements"
Column | Type | Collation | Nullable | Default
------------------------+--------------------------+-----------+----------+---------
userid | oid | | |
dbid | oid | | |
toplevel | boolean | | |
queryid | bigint | | |
query | text | | |
plans | bigint | | |
total_plan_time | double precision | | |
min_plan_time | double precision | | |
max_plan_time | double precision | | |
mean_plan_time | double precision | | |
stddev_plan_time | double precision | | |
calls | bigint | | |
total_exec_time | double precision | | |
min_exec_time | double precision | | |
max_exec_time | double precision | | |
mean_exec_time | double precision | | |
stddev_exec_time | double precision | | |
rows | bigint | | |
shared_blks_hit | bigint | | |
shared_blks_read | bigint | | |
shared_blks_dirtied | bigint | | |
shared_blks_written | bigint | | |
local_blks_hit | bigint | | |
local_blks_read | bigint | | |
local_blks_dirtied | bigint | | |
local_blks_written | bigint | | |
temp_blks_read | bigint | | |
temp_blks_written | bigint | | |
shared_blk_read_time | double precision | | |
shared_blk_write_time | double precision | | |
local_blk_read_time | double precision | | |
local_blk_write_time | double precision | | |
temp_blk_read_time | double precision | | |
temp_blk_write_time | double precision | | |
wal_records | bigint | | |
wal_fpi | bigint | | |
wal_bytes | numeric | | |
jit_functions | bigint | | |
jit_generation_time | double precision | | |
jit_inlining_count | bigint | | |
jit_inlining_time | double precision | | |
jit_optimization_count | bigint | | |
jit_optimization_time | double precision | | |
jit_emission_count | bigint | | |
jit_emission_time | double precision | | |
jit_deform_count | bigint | | |
jit_deform_time | double precision | | |
stats_since | timestamp with time zone | | |
minmax_stats_since | timestamp with time zone | | |
SELECT count(*) > 0 AS has_data FROM pg_stat_statements;
has_data
@ -310,4 +312,16 @@ SELECT count(*) > 0 AS has_data FROM pg_stat_statements;
t
(1 row)
-- New parameter minmax_only of pg_stat_statements_reset function
SELECT pg_get_functiondef('pg_stat_statements_reset'::regproc);
pg_get_functiondef
-------------------------------------------------------------------------------------------------------------------------------------------------------------------
CREATE OR REPLACE FUNCTION public.pg_stat_statements_reset(userid oid DEFAULT 0, dbid oid DEFAULT 0, queryid bigint DEFAULT 0, minmax_only boolean DEFAULT false)+
RETURNS timestamp with time zone +
LANGUAGE c +
PARALLEL SAFE STRICT +
AS '$libdir/pg_stat_statements', $function$pg_stat_statements_reset_1_11$function$ +
(1 row)
DROP EXTENSION pg_stat_statements;