Fortsættelse af artiklen ««.
Artiklen vil undersøge og vise med specifikke forespørgsler og eksempler, hvilken nyttig information der kan opnås ved hjælp af visningen pg_locks.
Advarsel.
På grund af emnets nyhed og den uafsluttede testperiode kan artiklen indeholde fejl. Kritik og kommentarer er meget velkomne og forventes.
Inddata
Historikken for visningen pg_locks
archive_locking
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
);I det væsentlige svarer tabellen til tabellen archive_pg_stat_activity, som er nærmere beskrevet her — og her —
For at udfylde kolonnen queryid benyttes funktionen
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 'Aktuel tid er mindre end 5 minutter.';
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;Forklaring: Værdien af kolonnen queryid opdateres i tabellen history_locking, og derefter, når en ny sektion oprettes for tabellen archive_locking, vil værdien blive gemt i historiske værdier.
Output
Generel information om processer samlet set.
VENTER PÅ LOCKS EFTER LOCKTYPER
Forespørgsel
MED
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 Eksempel
| VENTER PÅ LÅSE EFTER LÅSETYPER +--------------------+------------------------------+-------------------- | låsetype| tilstand| varighed +--------------------+------------------------------+-------------------- | transactionsid| ShareLock| 19:39:26 | tuple| AccessExclusiveLock| 00:03:35 +--------------------+------------------------------+--------------------
TAGS AF LÅSE EFTER LÅSETYPER
Forespørgsel
MED
t AS
(
SELECT
låsetype ,
tilstand ,
count(*) as total
FROM
activity_hist.archive_locking
WHERE
tidspunkt mellem pg_stat_history_begin+(current_hour_diff * interval '1 hour') OG pg_stat_history_end+(current_hour_diff * interval '1 hour') OG
givet
GROUP BY
låsetype ,
tilstand
)
SELECT
låsetype ,
tilstand ,
total * interval '1 second' as varighed
FROM t
ORDER BY 3 DESC Eksempel
| TAGS AF LÅSE EFTER LÅSETYPER +--------------------+------------------------------+-------------------- | låsetype| tilstand| varighed +--------------------+------------------------------+-------------------- | relation| RowExclusiveLock| 51:11:10 | virtualxid| ExclusiveLock| 48:10:43 | transactionsid| ExclusiveLock| 44:24:53 | relation| AccessShareLock| 20:06:13 | tuple| AccessExclusiveLock| 17:58:47 | tuple| ExclusiveLock| 01:40:41 | relation| ShareUpdateExclusiveLock| 00:26:41 | objekt| RowExclusiveLock| 00:00:01 | transactionsid| ShareLock| 00:00:01 | extend| ExclusiveLock| 00:00:01 +--------------------+------------------------------+--------------------
Detaljeret information om specifikke queryid forespørgsler
VENTER PÅ LÅSE EFTER LÅSETYPER EFTER QUERYID
Forespørgsel
MED
lt AS
(
SELECT
pid ,
låsetype ,
tilstand ,
tidspunkt ,
queryid ,
blocking_pids ,
MIN ( tidspunkt ) OVER (PARTITION BY pid , låsetype ,tilstand ) as startet
FROM
activity_hist.archive_locking
WHERE
tidspunkt mellem pg_stat_history_begin+(current_hour_diff * interval '1 hour') OG
pg_stat_history_end+(current_hour_diff * interval '1 hour') OG
IKKE givet OG
queryid ER IKKE NULL
GROUP BY
pid ,
låsetype ,
tilstand ,
tidspunkt ,
queryid ,
blocking_pids
)
SELECT
lt.pid ,
lt.låsetype ,
lt.tilstand ,
lt.startet ,
lt.queryid ,
lt.blocking_pids ,
COUNT(*) * interval '1 second' as varighed
FROM lt
GROUP BY
lt.pid ,
lt.låsetype ,
lt.tilstand ,
lt.startet ,
lt.queryid ,
lt.blocking_pids
ORDER BY 4Eksempel
| VENTER PÅ LÅSE EFTER LÅSETYPER EFTER SPØRGSMÅLID
+----------+-------------------------+--------------------+------------------------------+--------------------+--------------------+--------------------
| pid| låsetype| tilstand| startet| spørringid| blokkerende_pid| varighed
+----------+-------------------------+--------------------+------------------------------+--------------------+--------------------+--------------------
| 11288| transaktionsid| Delingslås| 2019-09-17 10:00:00.302936| 389015618226997618| {11092}| 00:03:34
| 11626| transaktionsid| Delingslås| 2019-09-17 10:00:21.380921| 389015618226997618| {12380}| 00:00:29
| 11626| transaktionsid| Delingslås| 2019-09-17 10:00:21.380921| 389015618226997618| {11092}| 00:03:25
| 11626| transaktionsid| Delingslås| 2019-09-17 10:00:21.380921| 389015618226997618| {12213}| 00:01:55
| 11626| transaktionsid| Delingslås| 2019-09-17 10:00:21.380921| 389015618226997618| {12751}| 00:00:01
| 11629| transaktionsid| Delingslås| 2019-09-17 10:00:24.331935| 389015618226997618| {11092}| 00:03:22
| 11629| transaktionsid| Delingslås| 2019-09-17 10:00:24.331935| 389015618226997618| {12007}| 00:00:01
| 12007| transaktionsid| Delingslås| 2019-09-17 10:05:03.327933| 389015618226997618| {11629}| 00:00:13
| 12007| transaktionsid| Delingslås| 2019-09-17 10:05:03.327933| 389015618226997618| {11092}| 00:01:10
| 12007| transaktionsid| Delingslås| 2019-09-17 10:05:03.327933| 389015618226997618| {11288}| 00:00:05
| 12213| transaktionsid| Delingslås| 2019-09-17 10:06:07.328019| 389015618226997618| {12007}| 00:00:10TAGNING AF LÅSE EFTER LÅSETYPER EFTER SPØRGSMÅLID
Forespørgsel
MED
lt SOM
(
SELECT
pid ,
låsetype ,
tilstand ,
tidspunkt ,
spørringid ,
blokkerende_pid ,
MIN ( tidspunkt ) OVER (PARTITION BY pid , låsetype ,tilstand ) as startet
FROM
aktivitet_hist.archive_locking
WHERE
tidspunkt mellem pg_stat_history_begin+(current_hour_diff * interval '1 hour') AND
pg_stat_history_end+(current_hour_diff * interval '1 hour') AND
bevilget AND
spørringid IS NOT NULL
GROUP BY
pid ,
låsetype ,
tilstand ,
tidspunkt ,
spørringid ,
blokkerende_pid
)
SELECT
lt.pid ,
lt.låsetype ,
lt.tilstand ,
lt.startet ,
lt.spørringid ,
lt.blokkerende_pid ,
COUNT(*) * interval '1 second' as varighed
FROM lt
GROUP BY
lt.pid ,
lt.låsetype ,
lt.tilstand ,
lt.startet ,
lt.spørringid ,
lt.blokkerende_pid
ORDER BY 4Eksempel
| TAGNING AF LÅSE AF LÅSTYPER EFTER QUERYID
+----------+-------------------------+--------------------+------------------------------+--------------------+--------------------+--------------------
| pid| låsetype| tilstand| startet| queryid| blokerende_pids| varighed
+----------+-------------------------+--------------------+------------------------------+--------------------+--------------------+--------------------
| 11288| relation| RowExclusiveLock| 2019-09-17 10:00:00.302936| 389015618226997618| {11092}| 00:03:34
| 11092| transactionid| ExclusiveLock| 2019-09-17 10:00:00.302936| 389015618226997618| {}| 00:03:34
| 11288| relation| RowExclusiveLock| 2019-09-17 10:00:00.302936| 389015618226997618| {}| 00:00:10
| 11092| relation| 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| transactionid| 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}| 00:03:34Brug af låsehistorik til analyse af ydeevneproblemer.
- Processen med pid=11288, der udfører en forespørgsel med queryid=389015618226997618, har ventet på en lås siden 2019-09-17 10:00:00 i 3 minutter.
- Låsen blev holdt af processen med pid=11092
- Processen med pid=11092, der udførte en forespørgsel med queryid=389015618226997618, holdt låsen siden 2019-09-17 10:00:00 i 3 minutter.
Resultat
Nu håber jeg, at det mest interessante og nyttige begynder – indsamling af statistik og analyse af tilfælde fra historikken om ventetider og låse.
I fremtiden håber jeg, at der vil komme et sæt noter (tilsvarende metalink fra Oracle).
Det er netop derfor, at den anvendte metode hurtigt fremvises til offentligheden.
Inden længe vil jeg forsøge at uploade projektet på github.
Kilde: habr.com
