PostgreSQL中取得鎖歷史的方法之一

文章繼續“嘗試為 PostgreSQL 建立 ASH 類似物 “。

本文將使用特定的查詢和範例來檢查並展示使用 pg_locks 視圖的歷史記錄可以獲得哪些有用的資訊。

警告。
由於主題新穎且測試期尚未完成，文章可能包含錯誤。 強烈歡迎和期待批評和意見。

輸入數據

pg_locks 表示的歷史

歸檔鎖定

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 
);

本質上，該表與該表類似 archive_pg_stat_activity，這裡有更詳細的描述 - pg_stat_statements + pg_stat_activity + loq_query = pg_ash？ 和這裡 - 嘗試為 PostgreSQL 建立 ASH 的類似物。

填充一列 查詢ID 使用函數

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;

說明： queryid列的值會在history_locking表中更新，然後當為archive_locking表建立新分區時，該值會儲存在歷史值中。

輸出

有關流程的一般資訊。

按鎖類型等待鎖

詢問

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 

例子

| 依鎖類型等待鎖+----------+------------------------ -------- + ------------------- | 鎖型| 模式| 持續時間+--------------------+-------------------------- - --+-------------------- | 交易ID| 共享鎖| 19:39:26 | 00:03:35 元組| 存取專屬鎖| XNUMX:XNUMX:XNUMX +-------------------+------------------------ - -------+----------

按鎖類型取得鎖

詢問

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 

例子

| 依鎖類型取得鎖+--------------------------------+----------- ------------- --------+-------------------- | 鎖型| 模式| 持續時間+--------------------+-------------------------- - --+-------------------- | 關係| 行獨佔鎖| 51:11:10 | 虛擬xid| 專屬鎖| 48:10:43 | 44:24:53 交易ID| 專屬鎖| 20:06:13 | 17:58:47 關係| 存取共享鎖| 01:40:41 | 00:26:41 元組| 存取專屬鎖| 00:00:01 | 00:00:01 元組| 專屬鎖| 00:00:01 | XNUMX:XNUMX:XNUMX 關係| 分享更新排他鎖| XNUMX:XNUMX:XNUMX | XNUMX:XNUMX:XNUMX 對象| 行獨佔鎖| XNUMX:XNUMX:XNUMX | 交易ID| 共享鎖| XNUMX:XNUMX:XNUMX | 延伸| 專屬鎖| XNUMX:XNUMX:XNUMX +--------------------------------+----------- ------------- - -------+----------

有關特定 queryid 請求的詳細信息

按查詢 ID 的鎖類型等待鎖

詢問

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

例子

| 依查詢ID 的鎖型別等待鎖+------------+----------+----- ------------ --- +----------------------------------------+--- -- --------------- -+--------------------+------------ ------------ --------- | PID| 鎖型| 模式| 開始| 查詢ID| 阻塞PID| 持續時間+----------+------------------------+--------- -- --------+----------------------------------------- -+--------- -----------+--------------------+------ ----------- --- | 11288| 交易ID| 共享鎖| 2019-09-17 10:00:00.302936| 389015618226997618| {11092}| 00:03:34 | 11626:2019:09 17| 交易ID| 共享鎖| 10-00-21.380921 389015618226997618:12380:00| 00| {29}| 11626:2019:09 | 17:10:00 21.380921| 交易ID| 共享鎖| 389015618226997618-11092-00 03:25:11626| 2019| {09}| 17:10:00 | 21.380921:389015618226997618:12213 00| 交易ID| 共享鎖| 01-55-11626 2019:09:17| 10| {00}| 21.380921:389015618226997618:12751 | 00:00:01 11629| 交易ID| 共享鎖| 2019-09-17 10:00:24.331935| 389015618226997618| {11092}| 00:03:22 | 11629| 交易ID| 共享鎖| 2019-09-17 10:00:24.331935| 389015618226997618| {12007}| 00:00:01 | 12007:2019:09 17| 交易ID| 共享鎖| 10-05-03.327933 389015618226997618:11629:00| 00| {13}| 12007:2019:09 | 17| 交易ID| 共享鎖| 10-05-03.327933 389015618226997618:11092:00| 01| {10}| 12007:2019:09 | 17:10:05 03.327933| 交易ID| 共享鎖| 389015618226997618-11288-00 00:05:12213| 2019| {09}| 17:10:06 | 07.328019:389015618226997618:12007 00| 交易ID| 共享鎖| 00-10-XNUMX XNUMX:XNUMX:XNUMX| XNUMX| {XNUMX}| XNUMX:XNUMX:XNUMX | XNUMX:XNUMX:XNUMX XNUMX| 交易ID| 共享鎖| XNUMX-XNUMX-XNUMX XNUMX:XNUMX:XNUMX| XNUMX| {XNUMX}| XNUMX:XNUMX:XNUMX

透過查詢 ID 按鎖類型取得鎖

詢問

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

例子

| 依查詢ID 依鎖類型取得鎖+---------+------------+----- ------------- -+ ----------------------------+---------------- --- -------------+ --------------------+--------------- --------- -------- | PID| 鎖型| 模式| 開始| 查詢ID| 阻塞PID| 持續時間+----------+------------------------+--------- -- -------+----------------------------------------+- -------- -- ----------+--------------------+-------- --------- -- - | 11288| 關係| 行獨佔鎖| 2019-09-17 10:00:00.302936| 389015618226997618| {11092}| 00:03:34 | 11092:2019:09 17| 交易ID| 專屬鎖| 10-00-00.302936 389015618226997618:00:03| 34| {}| 11288:2019:09 | 17:10:00 00.302936| 關係| 行獨佔鎖| 389015618226997618-00-00 10:11092:2019| 09| {}| 17:10:00 | 00.302936:389015618226997618:00 03| 關係| 行獨佔鎖| 34-11092-2019 09:17:10| 00| {}| 00.302936:389015618226997618:00 | 03:34:11288 2019| 虛擬xid| 專屬鎖| 09-17-10 00:00.302936:389015618226997618| 11092| {}| 00:03:34 | 11288:2019:09 17| 虛擬xid| 專屬鎖| 10-00-00.302936 389015618226997618:11092:00| 03| {34}| 11288:2019:09 | 17:10:00 00.302936| 交易ID| 專屬鎖| 389015618226997618-11092-00 03:34:XNUMX| XNUMX| {XNUMX}| XNUMX:XNUMX:XNUMX | XNUMX:XNUMX:XNUMX XNUMX| 元組| 存取專屬鎖| XNUMX-XNUMX-XNUMX XNUMX:XNUMX:XNUMX| XNUMX| {XNUMX}| XNUMX:XNUMX:XNUMX

使用鎖定歷史記錄來分析效能事件。

1. pid=389015618226997618的進程執行的queryid=11288的請求從2019-09-17 10:00:00開始等待阻塞3分鐘。
2. 鎖被 pid=11092 的進程持有
3. 從11092-389015618226997618-2019 09:17:10開始，pid=00的進程執行queryid=00的請求，持有鎖3分鐘。

總

現在，我希望，最有趣和最有用的部分將開始 - 收集統計數據並分析有關等待和阻塞歷史的案例。

未來，我想相信，我們會得到一套一些筆記（類似Oracle的metalink）。

一般來說，正是因為這個原因，所使用的方法論才會盡快提供給每個人。

我會嘗試在不久的將來將專案發佈到github上。

來源： www.habr.com