🥇Un dos métodos para obter o historial de bloqueos en PostgreSQL

Continuación do artigo "Un intento de crear un análogo ASH para PostgreSQL «.

O artigo examinará e mostrará, mediante consultas e exemplos específicos, que información útil se pode obter mediante o historial da vista pg_locks.

Aviso
Debido á novidade do tema e ao período de probas inacabado, o artigo pode conter erros. As críticas e os comentarios son moi ben recibidos e esperados.

Datos de entrada

Historia da representación de pg_locks

bloqueo_arquivo

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 
);

Esencialmente, a táboa é semellante á táboa archive_pg_stat_activity, descrito con máis detalle aquí - pg_stat_statements + pg_stat_activity + loq_query = pg_ash? e aquí - Un intento de crear un análogo de ASH para PostgreSQL.

Para encher unha columna queryid utilízase a función

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;

Explicación: o valor da columna queryid actualízase na táboa history_locking e, a continuación, cando se crea unha nova partición para a táboa archive_locking, o valor almacenarase nos valores históricos.

Saída

Información xeral dos procesos en xeral.

ESPERANDO PECHAS POR CERRADURAS

Solicitude

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

Exemplo

| ESPERANDO CERRADURAS POR TIPOS DE CERRADO +-----------+----------------------- --------+ ------------------- | tipo de bloqueo| modo| duración +--------------------+--------------------------- --+-------------------- | transacciónid| ShareLock| 19:39:26 | tupla| Acceso ExclusiveLock| 00:03:35 +-------------------+------------------------ -------+----------

TOMA DE CERRADURAS POR TIPOS DE CERRADO

Solicitude

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

Exemplo

| TOMA DE CERRADURAS POR TIPOS DE CERRADO +--------------------+------------------------ --------+------------------- | tipo de bloqueo| modo| duración +--------------------+--------------------------- --+-------------------- | relación| RowExclusiveLock| 51:11:10 | virtualxid| Bloqueo exclusivo| 48:10:43 | transacciónid| Bloqueo exclusivo| 44:24:53 | relación| AccessShareLock| 20:06:13 | tupla| Acceso ExclusiveLock| 17:58:47 | tupla| Bloqueo exclusivo| 01:40:41 | relación| ShareUpdateExclusiveLock| 00:26:41 | obxecto| RowExclusiveLock| 00:00:01 | transacciónid| ShareLock| 00:00:01 | estender| Bloqueo exclusivo| 00:00:01 +-------------------+------------------------ -------+----------

Información detallada sobre solicitudes específicas de queryid

ESPERANDO PERRADOS POR LOCKTYPES POR QUERYID

Solicitude

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

Exemplo

| ESPERANDO CERRADURAS POR LOCKTYPES POR QUERYID +----------+----------+----- ---------------- +----------------------------+--- ----------------- -+--------------------+----------- ---------- | pid| tipo de bloqueo| modo| comezou| queryid| bloqueo_pids| duración +----------+-------------------------+------------ ---------+------------------------------+---------- -----------+--------------------+------------------ --- | 11288| transacciónid| ShareLock| 2019/09/17 10:00:00.302936| 389015618226997618| {11092}| 00:03:34 | 11626| transacciónid| ShareLock| 2019/09/17 10:00:21.380921| 389015618226997618| {12380}| 00:00:29 | 11626| transacciónid| ShareLock| 2019/09/17 10:00:21.380921| 389015618226997618| {11092}| 00:03:25 | 11626| transacciónid| ShareLock| 2019/09/17 10:00:21.380921| 389015618226997618| {12213}| 00:01:55 | 11626| transacciónid| ShareLock| 2019/09/17 10:00:21.380921| 389015618226997618| {12751}| 00:00:01 | 11629| transacciónid| ShareLock| 2019/09/17 10:00:24.331935| 389015618226997618| {11092}| 00:03:22 | 11629| transacciónid| ShareLock| 2019/09/17 10:00:24.331935| 389015618226997618| {12007}| 00:00:01 | 12007| transacciónid| ShareLock| 2019/09/17 10:05:03.327933| 389015618226997618| {11629}| 00:00:13 | 12007| transacciónid| ShareLock| 2019/09/17 10:05:03.327933| 389015618226997618| {11092}| 00:01:10 | 12007| transacciónid| ShareLock| 2019/09/17 10:05:03.327933| 389015618226997618| {11288}| 00:00:05 | 12213| transacciónid| ShareLock| 2019/09/17 10:06:07.328019| 389015618226997618| {12007}| 00:00:10

COLLANDO CERRADURAS POR LOCKTYPES POR QUERYID

Solicitude

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

Exemplo

| COLLANDO CERRADURAS POR LOCKTYPES POR QUERYID +----------+----------+------ ---------------+ ----------------------------+---- ----------------+ --------------------+------------ -------- | pid| tipo de bloqueo| modo| comezou| queryid| bloqueo_pids| duración +----------+-------------------------+------------ ---------+------------------------------+---------- -----------+--------------------+------------------ --- | 11288| relación| RowExclusiveLock| 2019/09/17 10:00:00.302936| 389015618226997618| {11092}| 00:03:34 | 11092| transacciónid| Bloqueo exclusivo| 2019/09/17 10:00:00.302936| 389015618226997618| {}| 00:03:34 | 11288| relación| RowExclusiveLock| 2019/09/17 10:00:00.302936| 389015618226997618| {}| 00:00:10 | 11092| relación| RowExclusiveLock| 2019/09/17 10:00:00.302936| 389015618226997618| {}| 00:03:34 | 11092| virtualxid| Bloqueo exclusivo| 2019/09/17 10:00:00.302936| 389015618226997618| {}| 00:03:34 | 11288| virtualxid| Bloqueo exclusivo| 2019/09/17 10:00:00.302936| 389015618226997618| {11092}| 00:03:34 | 11288| transacciónid| Bloqueo exclusivo| 2019/09/17 10:00:00.302936| 389015618226997618| {11092}| 00:03:34 | 11288| tupla| Acceso ExclusiveLock| 2019/09/17 10:00:00.302936| 389015618226997618| {11092}| 00:03:34

Usando o historial de bloqueo para analizar incidentes de rendemento.

Unha solicitude con queryid=389015618226997618 executada por un proceso con pid=11288 estaba á espera do bloqueo a partir do 2019/09/17 ás 10:00:00 durante 3 minutos.
O bloqueo realizouse mediante un proceso con pid=11092
Un proceso con pid=11092 executando unha solicitude con queryid=389015618226997618 a partir do 2019/09/17 ás 10:00:00 mantivo o bloqueo durante 3 minutos.

Total

Agora, espero, comezará a parte máis interesante e útil: recoller estatísticas e analizar casos sobre o historial de esperas e bloqueos.

No futuro, quero crer, obteremos un conxunto dalgunhas notas (semellante ao metalink de Oracle).

En xeral, é por iso que a metodoloxía empregada ponse a disposición de todos o máis rápido posible.

Tentarei publicar o proxecto en github nun futuro próximo.

Fonte: www.habr.com

Un dos métodos para obter o historial de bloqueos en PostgreSQL

Datos de entrada

Historia da representación de pg_locks

Saída

ESPERANDO PECHAS POR CERRADURAS

TOMA DE CERRADURAS POR TIPOS DE CERRADO

ESPERANDO PERRADOS POR LOCKTYPES POR QUERYID

COLLANDO CERRADURAS POR LOCKTYPES POR QUERYID

Total

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