Pokračovanie článku "
Tento článok zváži a ukáže na konkrétnych dotazoch a príkladoch, aké užitočné informácie možno získať pomocou histórie zobrazenia pg_locks.
Varovanie.
Vzhľadom na novosť témy a neúplnosť testovacieho obdobia môže článok obsahovať chyby. Kritika a komentáre sú vítané a očakávané.
Vstupné Data
históriu reprezentácie pg_locks
uzamykanie archívu
CREATE TABLE archive_locking
( timepoint timestamp without time zone ,
locktype text ,
relation oid ,
mode text ,
tid xid ,
vtid text ,
pid integer ,
blocking_pids integer[] ,
granted boolean ,
queryid bigint
);
V podstate je tabuľka podobná tabuľke archive_pg_stat_activitypodrobnejšie popísané tu -
Na vyplnenie stĺpca queryid používa sa funkcia
update_history_locking_by_queryid
--update_history_locking_by_queryid.sql
CREATE OR REPLACE FUNCTION update_history_locking_by_queryid() RETURNS boolean AS $$
DECLARE
result boolean ;
current_minute double precision ;
start_minute integer ;
finish_minute integer ;
start_period timestamp without time zone ;
finish_period timestamp without time zone ;
lock_rec record ;
endpoint_rec record ;
current_hour_diff double precision ;
BEGIN
RAISE NOTICE '***update_history_locking_by_queryid';
result = TRUE ;
current_minute = extract ( minute from now() );
SELECT * FROM endpoint WHERE is_need_monitoring
INTO endpoint_rec ;
current_hour_diff = endpoint_rec.hour_diff ;
IF current_minute < 5
THEN
RAISE NOTICE 'Current time is less than 5 minute.';
start_period = date_trunc('hour',now()) + (current_hour_diff * interval '1 hour');
finish_period = start_period - interval '5 minute' ;
ELSE
finish_minute = extract ( minute from now() ) / 5 ;
start_minute = finish_minute - 1 ;
start_period = date_trunc('hour',now()) + interval '1 minute'*start_minute*5+(current_hour_diff * interval '1 hour');
finish_period = date_trunc('hour',now()) + interval '1 minute'*finish_minute*5+(current_hour_diff * interval '1 hour') ;
END IF ;
RAISE NOTICE 'start_period = %', start_period;
RAISE NOTICE 'finish_period = %', finish_period;
FOR lock_rec IN
WITH act_queryid AS
(
SELECT
pid ,
timepoint ,
query_start AS started ,
MAX(timepoint) OVER (PARTITION BY pid , query_start ) AS finished ,
queryid
FROM
activity_hist.history_pg_stat_activity
WHERE
timepoint BETWEEN start_period and
finish_period
GROUP BY
pid ,
timepoint ,
query_start ,
queryid
),
lock_pids AS
(
SELECT
hl.pid ,
hl.locktype ,
hl.mode ,
hl.timepoint ,
MIN ( timepoint ) OVER (PARTITION BY pid , locktype ,mode ) as started
FROM
activity_hist.history_locking hl
WHERE
hl.timepoint between start_period and
finish_period
GROUP BY
hl.pid ,
hl.locktype ,
hl.mode ,
hl.timepoint
)
SELECT
lp.pid ,
lp.locktype ,
lp.mode ,
lp.timepoint ,
aq.queryid
FROM lock_pids lp LEFT OUTER JOIN act_queryid aq ON ( lp.pid = aq.pid AND lp.started BETWEEN aq.started AND aq.finished )
WHERE aq.queryid IS NOT NULL
GROUP BY
lp.pid ,
lp.locktype ,
lp.mode ,
lp.timepoint ,
aq.queryid
LOOP
UPDATE activity_hist.history_locking SET queryid = lock_rec.queryid
WHERE pid = lock_rec.pid AND locktype = lock_rec.locktype AND mode = lock_rec.mode AND timepoint = lock_rec.timepoint ;
END LOOP;
RETURN result ;
END
$$ LANGUAGE plpgsql;
vysvetlenie: hodnota stĺpca queryid sa aktualizuje v tabuľke history_locking a potom, keď sa vytvorí nový oddiel pre tabuľku archive_locking, hodnota sa uloží do historických hodnôt.
Výkon
Všeobecné informácie o procesoch všeobecne.
ČAKANIE NA ZÁMKY PODĽA TYPU ZÁMKOV
Žiadosť
WITH
t AS
(
SELECT
locktype ,
mode ,
count(*) as total
FROM
activity_hist.archive_locking
WHERE
timepoint between pg_stat_history_begin+(current_hour_diff * interval '1 hour') AND pg_stat_history_end+(current_hour_diff * interval '1 hour') AND
NOT granted
GROUP BY
locktype ,
mode
)
SELECT
locktype ,
mode ,
total * interval '1 second' as duration
FROM t
ORDER BY 3 DESC
Príklad
| ČAKÁ SA NA ZÁMKY PODĽA TYPU ZÁMKOV +--------------------+----------------------- -------+--------------------- | typ zámku| režim| trvanie +--------------------+--------------------- ---+-- ------------------- | id transakcie| sharelock| 19:39:26 | tuple| AccessExclusiveLock| 00:03:35 +--------------------+------------------------ -------+---------------------
ODBER ZÁMKOV PODĽA TYPU ZÁMKOV
Žiadosť
WITH
t AS
(
SELECT
locktype ,
mode ,
count(*) as total
FROM
activity_hist.archive_locking
WHERE
timepoint between pg_stat_history_begin+(current_hour_diff * interval '1 hour') AND pg_stat_history_end+(current_hour_diff * interval '1 hour') AND
granted
GROUP BY
locktype ,
mode
)
SELECT
locktype ,
mode ,
total * interval '1 second' as duration
FROM t
ORDER BY 3 DESC
Príklad
| ODBER ZÁMKOV PODĽA TYPU ZÁMKOV +--------------------+------------------------ -------+--------------------- | typ zámku| režim| trvanie +--------------------+--------------------- ---+-- ------------------- | vzťah| RowExclusiveLock| 51:11:10 | virtualxid| ExclusiveLock| 48:10:43 | id transakcie| ExclusiveLock| 44:24:53 | vzťah| AccessShareLock| 20:06:13 | tuple| AccessExclusiveLock| 17:58:47 | tuple| ExclusiveLock| 01:40:41 | vzťah| ShareUpdateExclusiveLock| 00:26:41 | objekt| RowExclusiveLock| 00:00:01 | id transakcie| sharelock| 00:00:01 | predĺžiť| ExclusiveLock| 00:00:01 +--------------------+------------------------ -------+---------------------
Podrobné informácie pre konkrétne dotazy na ID dotazu
ČAKANIE NA ZÁMKY PODĽA TYPU ZÁMKOV PODĽA QUERYID
Žiadosť
WITH
lt AS
(
SELECT
pid ,
locktype ,
mode ,
timepoint ,
queryid ,
blocking_pids ,
MIN ( timepoint ) OVER (PARTITION BY pid , locktype ,mode ) as started
FROM
activity_hist.archive_locking
WHERE
timepoint between pg_stat_history_begin+(current_hour_diff * interval '1 hour') AND
pg_stat_history_end+(current_hour_diff * interval '1 hour') AND
NOT granted AND
queryid IS NOT NULL
GROUP BY
pid ,
locktype ,
mode ,
timepoint ,
queryid ,
blocking_pids
)
SELECT
lt.pid ,
lt.locktype ,
lt.mode ,
lt.started ,
lt.queryid ,
lt.blocking_pids ,
COUNT(*) * interval '1 second' as duration
FROM lt
GROUP BY
lt.pid ,
lt.locktype ,
lt.mode ,
lt.started ,
lt.queryid ,
lt.blocking_pids
ORDER BY 4
Príklad
| ČAKANIE NA ZÁMKY PODĽA TYPU ZÁMKOV PODĽA QUERYID +----------+-------------------------+------ ---------------+-------------------------------+--- ------------------+--------------------+----------- - --------- | pid| typ zámku| režim| začalo| queryid| blocking_pids| trvanie +----------+-------------------------+------------ ---------+------------------------------+---------- -----------+--------------------+------------------ --- | 11288| id transakcie| sharelock| 2019-09-17 10:00:00.302936| 389015618226997618| {11092}| 00:03:34 | 11626| id transakcie| sharelock| 2019-09-17 10:00:21.380921| 389015618226997618| {12380}| 00:00:29 | 11626| id transakcie| sharelock| 2019-09-17 10:00:21.380921| 389015618226997618| {11092}| 00:03:25 | 11626| id transakcie| sharelock| 2019-09-17 10:00:21.380921| 389015618226997618| {12213}| 00:01:55 | 11626| id transakcie| sharelock| 2019-09-17 10:00:21.380921| 389015618226997618| {12751}| 00:00:01 | 11629| id transakcie| sharelock| 2019-09-17 10:00:24.331935| 389015618226997618| {11092}| 00:03:22 | 11629| id transakcie| sharelock| 2019-09-17 10:00:24.331935| 389015618226997618| {12007}| 00:00:01 | 12007| id transakcie| sharelock| 2019-09-17 10:05:03.327933| 389015618226997618| {11629}| 00:00:13 | 12007| id transakcie| sharelock| 2019-09-17 10:05:03.327933| 389015618226997618| {11092}| 00:01:10 | 12007| id transakcie| sharelock| 2019-09-17 10:05:03.327933| 389015618226997618| {11288}| 00:00:05 | 12213| id transakcie| sharelock| 2019-09-17 10:06:07.328019| 389015618226997618| {12007}| 00:00:10
PREBERANIE ZÁMKOV PODĽA TYPU ZÁMKOV PODĽA QUERYID
Žiadosť
WITH
lt AS
(
SELECT
pid ,
locktype ,
mode ,
timepoint ,
queryid ,
blocking_pids ,
MIN ( timepoint ) OVER (PARTITION BY pid , locktype ,mode ) as started
FROM
activity_hist.archive_locking
WHERE
timepoint between pg_stat_history_begin+(current_hour_diff * interval '1 hour') AND
pg_stat_history_end+(current_hour_diff * interval '1 hour') AND
granted AND
queryid IS NOT NULL
GROUP BY
pid ,
locktype ,
mode ,
timepoint ,
queryid ,
blocking_pids
)
SELECT
lt.pid ,
lt.locktype ,
lt.mode ,
lt.started ,
lt.queryid ,
lt.blocking_pids ,
COUNT(*) * interval '1 second' as duration
FROM lt
GROUP BY
lt.pid ,
lt.locktype ,
lt.mode ,
lt.started ,
lt.queryid ,
lt.blocking_pids
ORDER BY 4
Príklad
| ZABLOKOVANIE ZÁMKOV PODĽA TYPU ZÁMKOV PODĽA QUERYID +----------+-------------------------+------- --------------+-------------------------------+---- -+--------------------+------------ --------- | pid| typ zámku| režim| začalo| queryid| blocking_pids| trvanie +----------+-------------------------+------------ ---------+------------------------------+---------- ---+--------------------+----------------- --- | 11288| vzťah| RowExclusiveLock| 2019-09-17 10:00:00.302936| 389015618226997618| {11092}| 00:03:34 | 11092| id transakcie| ExclusiveLock| 2019-09-17 10:00:00.302936| 389015618226997618| {}| 00:03:34 | 11288| vzťah| RowExclusiveLock| 2019-09-17 10:00:00.302936| 389015618226997618| {}| 00:00:10 | 11092| vzťah| RowExclusiveLock| 2019-09-17 10:00:00.302936| 389015618226997618| {}| 00:03:34 | 11092| virtualxid| ExclusiveLock| 2019-09-17 10:00:00.302936| 389015618226997618| {}| 00:03:34 | 11288| virtualxid| ExclusiveLock| 2019-09-17 10:00:00.302936| 389015618226997618| {11092}| 00:03:34 | 11288| id transakcie| ExclusiveLock| 2019-09-17 10:00:00.302936| 389015618226997618| {11092}| 00:03:34 | 11288| tuple| AccessExclusiveLock| 2019-09-17 10:00:00.302936| 389015618226997618| {11092}| 00:03:34
Použitie histórie blokovania pri analýze incidentov výkonu.
- Dotaz s queryid=389015618226997618 vykonaný procesom s pid=11288 čaká na uzamknutie od 2019-09-17 10:00:00 3 minúty.
- Zámok bol držaný procesom s pid=11092
- Proces s pid=11092 vykonávajúci dotaz s queryid=389015618226997618 od 2019 09:17:10 podržal zámok na 00 minúty.
Celkový
Teraz, dúfam, začne to najzaujímavejšie a najužitočnejšie - zhromažďovanie štatistík a analýza prípadov histórie očakávaní a blokovania.
V budúcnosti by som chcel veriť, že dostanete sadu akýchsi poznámok (podobných metalinke od Oracle).
Vo všeobecnosti je to preto, aby sa použitá metodika čo najrýchlejšie zobrazila verejnosti.
Vo veľmi blízkej budúcnosti sa pokúsim umiestniť projekt na github.
Zdroj: hab.com