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pg_stat_statements + pg_stat_activity + loq_query = pg_ash?

Som kort tilleggsinformasjon til artikkelen Forsøk på å lage et tilsvarende ASH for PostgreSQL.

Oppgave

Det er nødvendig å koble historikken til pg_stat_statements, pg_stat_activity. Som følge av dette, ved hjelp av historikken til planene som kommer fra service-tabellen log_query, kan man få mye nyttig informasjon for bruk i løsning av ytelsesproblemer og optimalisering av forespørselene.

Advarsel.

På grunn av fortsatt testing og utvikling kan ikke artikkelen anses som en beskrivelse av en ferdig industri løsning.

Kritikk og kommentarer til implementeringen er alltid velkomne og forventes.

Inndata

Tabell history_pg_stat_activity

--ACTIVITY_HIST.HISTORY_PG_STAT_ACTIVITY
DROP TABLE IF EXISTS activity_hist.history_pg_stat_activity;
CREATE TABLE activity_hist.history_pg_stat_activity
(
  timepoint timestamp without time zone ,
  datid             oid  , 
  datname           name ,
  pid               integer,
  usesysid          oid    ,
  usename           name   ,
  application_name  text   ,
  client_addr       inet   ,
  client_hostname   text   ,
  client_port       integer,
  backend_start     timestamp without time zone ,
  xact_start        timestamp without time zone ,
  query_start       timestamp without time zone ,
  state_change      timestamp without time zone ,
  wait_event_type   text ,                     
  wait_event        text ,                   
  state             text ,                  
  backend_xid       xid  ,                 
  backend_xmin      xid  ,                
  query             text ,               
  backend_type      text ,
  queryid           bigint
);

Tabell pg_stat_db_queries

CREATE TABLE pg_stat_db_queries
(
  database_id integer ,
  queryid bigint ,
  query text ,
  max_time double precision
);

Materialisert visning mvw_pg_stat_queries

CREATE MATERIALIZED VIEW public.mvw_pg_stat_queries AS
 SELECT t.queryid,
    t.max_time,
    t.query
   FROM public.dblink('LINK1'::text, 'SELECT queryid , max_time , query FROM pg_stat_statements WHERE dbid=(SELECT oid FROM  pg_database WHERE datname=current_database() ) AND max_time >= 0 '::text) t(queryid bigint, max_time double precision, query text)
  WITH NO DATA;

Tabell log_query

CREATE TABLE log_query
(
  id  integer ,
  queryid  bigint ,
  query_md5hash  text ,
  database_id  integer ,
  timepoint  timestamp without time zone , 
  query  text ,
  explained_plan  text[] , 
  plan_md5hash  text ,
  explained_plan_wo_costs  text[] , 
  plan_hash_value  text ,
  ip  text,
  port  text , 
  pid  integer 
);

Generell algoritme

Oppdater tabellen pg_stat_db_queries

Oppdater det materialiserte visningen mvw_pg_stat_queries

OPPRETT ELLER ERSTATTE FUNKSJON refresh_pg_stat_queries_list( database_id int) RETURNERER BOOLEAN AS $$
DEKLARER
 resultat BOOLEAN ;
 database_rec record ;  
BEGIN   
  SELECT *
  INTO database_rec
  FRA endpoint e JOIN database d ON e.id = d.endpoint_id 
  HVOR d.id = database_id  ;  
  
  IF IKKE database_rec.is_need_monitoring THEN RAISE NOTICE 'INGEN OVERVÅKNING NEEDED FOR database_id=%',database_id; return TRUE ; END IF ;
  
  EXECUTE 'SELECT dblink_connect(''LINK1'',''host='||database_rec.host||' port=5432 dbname='||database_rec.name||
		                                         ' user='||database_rec.s_name||' password='||database_rec.s_pass|| ' '')';
   
  REFRESH MATERIALIZED VIEW mvw_pg_stat_queries ;
  
  PERFORM dblink_disconnect('LINK1');  

  RETURN resultat;
END
$$ SPRÅK plpgsql;

Fyll ut tabellen pg_stat_db_queries

OPPRETT ELLER ERSTATTE FUNKSJON refresh_pg_stat_db_queries( ) RETURNERER BOOLEAN AS $$
DEKLARER
 resultat BOOLEAN ;
 database_rec record ;  
 pg_stat_rec record ;
BEGIN 
  TRUNCATE pg_stat_db_queries;
  
  
  FOR database_rec IN
  SELECT *
  FRA database d 
  LOOP
  
    IF IKKE database_rec.is_need_monitoring THEN RAISE NOTICE 'INGEN OVERVÅKNING NEEDED FOR database_id=%',database_rec.id; CONTINUE ; END IF ;
   
    PERFORM refresh_pg_stat_queries_list( database_rec.id ) ; 
	
	FOR pg_stat_rec IN
	SELECT * 
	FRA mvw_pg_stat_queries 
	LOOP
	  INSERT INTO pg_stat_db_queries
	  ( database_id , queryid , query , max_time )
	  VALUES
	  ( database_rec.id , pg_stat_rec.queryid , pg_stat_rec.query , pg_stat_rec.max_time);
	END LOOP;     
  END LOOP; 

  RETURN TRUE;
END
$$ SPRÅK plpgsql;

Som et resultat inneholder tabellen normaliserte tekstforespørsler, queryid, og maksimal kjøretid for forespørselen på nåværende tidspunkt (brukes til overvåking).

Fylling av log_query og dannelse av historien for utførelsesplaner.

Den aktuelle tekstforespørselen hentes fra loggfilen. Loggfilen fra målværtet til overvåkningsverten overføres delvis, med en bash-skript, via cron. For å spare plass og på grunn av den trivielle oppgaven med å kopiere deler av tekstfilen fra vert til vert, er ikke skriptet inkludert.

Parsing av loggfilen og ekstraksjon av tekstforespørselen

#!/bin/bash
#########################################################
# upload_log_query.sh
# Upload table table from dowloaded aws file 
# version 12.0
###########################################################  
echo 'TIMESTAMP:'$(date +%c)' Upload log_query table '

source_file=$1
echo 'source_file='$source_file

database_id=$2
echo 'database_id='$database_id

database_name=$3
echo 'database_name='$database_name


beginer=' '
first_line='1'
let "line_count=0"
sql_line=' '
sql_flag=' '    
space=' '
cat $source_file | while read line
do
  #first line will be passed
  if [[ $line_count == '0' ]]; then 
    let "line_count++" 
    continue 
  fi
  
  line="$space$line"
  #echo 'line='$line

  if [[ $first_line == "1" ]]; then
    beginer=`echo $line | awk -F" " '{ print $1}' `
    first_line='0'
  fi

  current_beginer=`echo $line | awk -F" " '{ print $1}' `
  #echo 'current_beginer='$current_beginer
  #echo 'beginer='$beginer
  

  if [[ $current_beginer == $beginer ]]; then
   if [[ $sql_flag == '1' ]]; then
     sql_flag='0' 
     #echo 'TIMESTAMP:'$(date +%c)' Upload log_query table : SQL STATEMENT ='"$sql_line"

     log_date=`echo $sql_line | awk -F" " '{ print $1}' `
     #echo 'log_date='$log_date

     log_time=`echo $sql_line | awk -F" " '{ print $2}' `
     #echo 'log_time='$log_time
     
     duration=`echo $sql_line | awk -F" " '{ print $5}' `
     #echo 'duration='$duration

	 connect=`echo $sql_line | awk -F" " '{ print $3}' `
	 userdb=`echo $connect | awk -F":" '{ print $3}' `
	 userdb2=$userdb'@'
	 db_port_log=`echo $connect | awk -F"@" '{ print $2}' `
	 log_database_name=`echo $db_port_log | awk -F":" '{ print $1}' `
	 
	 
	 #echo 'connect='$connect
	 #echo 'userdb='$userdb
	 #echo 'userdb2='$userdb2
	 #echo 'db_port_log='$db_port_log
	 #echo 'log_database_name='$log_database_name
	 
	 if [[  "$log_database_name" != "$database_name" ]];
	 then
	   echo '*** database_name '$log_database_name' from log is not equal '$database_name' CONTINUE '
	   continue;
	 fi
	 
     #replace ' to ''
     sql_modline=`echo "$sql_line" | sed 's/'''/''''''/g'`
     sql_line=' '
	 #echo '*********************************log_query start'
     #echo 'pid_str='$pid_str 
	 #echo 'ip_port='$ip_port 
	 #echo 'database_id='$database_id 
	 #echo 'log_date='$log_date
	 #echo 'log_time='$log_time
	 #echo 'duration='$duration
	 #echo 'sql_modline='$sql_modline
     if ! psql -U monitor -d monitor -v ON_ERROR_STOP=1 -A -t -q -c "select log_query( '$pid_str' , '$ip_port' , $database_id , '$log_date' , '$log_time' , '$duration' , '$sql_modline' )"
     then
        echo 'FATAL_ERROR - log_query '
        exit 1
     fi
	 #echo '**********************************log_query finish'

    fi #if [[ $sql_flag == '1' ]]; then

    let "line_count=line_count+1"
    #echo 'line_count= '$line_count
    #echo $line

    #check=`echo $line | awk -F" " '{ print $8}' `
    #check_sql=${check^^}    

    #echo 'check_sql='$check_sql
    
	if [[ ${line^^} =~ "SELECT" ]]; 
	then 
	 if [[ $line =~ "duration:" ]];
	 then
	    test_statement=`echo $line | awk -F" " '{ print $8}'` 
		is_select=${test_statement^^}		
		
		#echo 'test_statement='$test_statement
		#echo 'is_select='$is_select
		
        if [[ $is_select == 'SELECT' ]]; 
        then		
		  sql_flag='1'    
		  sql_line="$sql_line$line"
		  ip_port=`echo $sql_line | awk -F":" '{ print $4}' `
		  pid_str=`echo $sql_line | awk -F":" '{ print $6}' `
		fi
	 fi	 
    fi
  else       
    #echo $line
    #echo 'sql_flag ='$sql_flag

    if [[ $sql_flag == '1' ]]; then
      sql_line="$sql_line$line"
    fi   
    
  fi #if [[ $current_beginer == $beginer ]]; then

done

Fylling av tabellen log_query

--log_query.sql
--sett inn ny forespørsel i log_query-tabellen
CREATE OR REPLACE FUNCTION log_query( pid_str text , ip_port text ,log_database_id integer , log_date text , log_time text , duration text , sql_line text ) RETURNS boolean AS $$
DECLARE
  result boolean ;
  log_timepoint timestamp uten tids sone ;
  log_duration double precision ; 
  pos integer ;
  log_query text ;
  activity_string text ;
  log_md5hash text ;
  log_explain_plan text[] ;
  
  log_planhash text ;
  log_plan_wo_costs text[] ; 
  
  database_rec record ;
  
  pg_stat_query text ; 
  test_log_query text ;
  metric_rec record;
  log_query_rec record;
  found_flag boolean;
  
  pg_stat_history_rec record ;
  port_start integer ;
  port_end integer ;
  client_ip text ;
  client_port text ;
  log_queryid bigint ;
  log_query_text text ;
  pg_stat_query_text text ; 
  current_pid_str text ;
  current_pid integer;
  pid_start_pos integer ;
  pid_finish_pos integer ;
  
BEGIN
  result = TRUE ;    
  
  IF ip_port != '[local]' THEN
    port_start = position('(' in ip_port);
    port_end = position(')' in ip_port);
    client_ip = substring( ip_port from 1 for port_start-1 );
    client_port = substring( ip_port from port_start+1 for port_end-port_start-1 );
  ELSE 
    client_ip = 'lokal';
	client_port = 'lokal';
  END IF; 
  
  pid_start_pos = position('[' in pid_str);
  pid_finish_pos = position(']' in pid_str);
  current_pid_str=substring( pid_str from 2 for pid_finish_pos - pid_start_pos -1 );
  current_pid = to_number(current_pid_str , '999999999999');
  
  SELECT e.host , d.name , d.owner_pwd , d.owner_user
  INTO database_rec
  FROM database d JOIN endpoint e ON e.id = d.endpoint_id
  WHERE d.id = log_database_id ;
  
  log_timepoint = to_timestamp(log_date||' '||log_time,'YYYY-MM-DD HH24-MI-SS');
  log_duration = duration::double precision ; 
    
  pos = position ('SELECT' in UPPER(sql_line) );
  log_query = substring( sql_line from pos for LENGTH(sql_line));
  log_query = regexp_replace(log_query,' +',' ','g');
  log_query = regexp_replace(log_query,';+','','g');
  log_query = trim(trailing ' ' from log_query);
  
  log_md5hash = md5( log_query::text );
  
  --Forklar kjøreplan--
EXECUTE 'SELECT dblink_connect(''LINK1'',''host='||database_rec.host||' port=5432 dbname='||database_rec.name||' user='||database_rec.owner_user||' password='||database_rec.owner_pwd||' '')'; 
  
  log_explain_plan = ARRAY ( SELECT * FROM dblink('LINK1', 'EXPLAIN '||log_query ) AS t (plan text) );
  log_plan_wo_costs = ARRAY ( SELECT * FROM dblink('LINK1', 'EXPLAIN ( COSTS FALSE ) '||log_query ) AS t (plan text) );
  
  PERFORM dblink_disconnect('LINK1');
  --------------------------
  BEGIN
	INSERT INTO log_query
	(
		query_md5hash ,
		database_id , 
		timepoint ,
		duration ,
		query ,
		explained_plan ,
		plan_md5hash , 
		explained_plan_wo_costs , 
		plan_hash_value , 
		ip , 
		port ,
		pid
	) 
	VALUES 
	(
		log_md5hash ,
		log_database_id , 
		log_timepoint , 
		log_duration , 
		log_query ,
		log_explain_plan , 
		md5(log_explain_plan::text) ,
		log_plan_wo_costs , 
		md5(log_plan_wo_costs::text),
		client_ip , 
		client_port , 
		current_pid
		
	);
	activity_string = 	'Ny forespørsel har blitt logget '||
						' database_id = '|| log_database_id ||
						' query_md5hash='||log_md5hash||
						' , timepoint = '||to_char(log_timepoint,'YYYYMMDD HH24:MI:SS');
	PERFORM pg_log( log_database_id , 'log_query' , activity_string);  

	EXCEPTION
	  WHEN unique_violation THEN
		activity_string = 	'UNNTAK *** forespørselen er allerede logget '||
							' database_id = '|| log_database_id ||
							' query_md5hash='||log_md5hash||
							' , timepoint = '||to_char(log_timepoint,'YYYYMMDD HH24:MI:SS');					 
        PERFORM pg_log( log_database_id , 'log_query' , activity_string);
	END;

	SELECT 	queryid
	INTO   	log_queryid
	FROM 	log_query 
	WHERE 	query_md5hash = log_md5hash AND
			timepoint = log_timepoint;

	IF log_queryid IS NOT NULL 
	THEN 
	  RETURN result;
	END IF;
	
	------------------------------------------------
	SELECT * 
	INTO log_query_rec
	FROM log_query
	WHERE query_md5hash = log_md5hash AND timepoint = log_timepoint ; 
	
	log_query_rec.query=regexp_replace(log_query_rec.query,';+','','g');

	FOR pg_stat_history_rec IN
	 SELECT 
            queryid ,
  	    query 
	 FROM 
       pg_stat_db_queries 
     WHERE  
	   database_id = log_database_id AND
       queryid is not null 
	LOOP
	  pg_stat_query = pg_stat_history_rec.query ; 
	  pg_stat_query=regexp_replace(pg_stat_query,'n+',' ','g');
	  pg_stat_query=regexp_replace(pg_stat_query,'t+',' ','g');
	  pg_stat_query=regexp_replace(pg_stat_query,' +',' ','g');
	  pg_stat_query=regexp_replace(pg_stat_query,'$.','%','g');
	
	  log_query_text = trim(trailing ' ' from log_query_rec.query);
	  pg_stat_query_text = pg_stat_query;   
	  
	  IF (log_query_text LIKE pg_stat_query_text) THEN
		found_flag = TRUE ;
	  ELSE
		found_flag = FALSE ;
	  END IF;	  

	  IF found_flag THEN
	    
		UPDATE log_query SET queryid = pg_stat_history_rec.queryid WHERE query_md5hash = log_md5hash AND timepoint = log_timepoint ;
		activity_string = 	' oppdatert queryid = '||pg_stat_history_rec.queryid||
		                    ' for log_query med id = '||log_query_rec.id;					
		EXIT ;
	  END IF ;	  
	END LOOP ;	
  RETURN result ;
END
$$ LANGUAGE plpgsql;

Som tabellen innehelder den oppdaterte teksten til forespørselen, utførelsesplanene, hashen av utførelsesplanen, hashen av forespørselsteksten.

Fyll ut verdien queryid i tabellen history_pg_stat_activity

update_history_pg_stat_activity_by_queryid.sql

--update_history_pg_stat_activity_by_queryid.sql
CREATE OR REPLACE FUNCTION update_history_pg_stat_activity_by_queryid() RETURNS boolean AS $$
DECLARE
  result boolean ;
  history_pg_stat_activity_rec record ; 
  pg_stat_query text ;
  pg_stat_query_text text ;
  pg_stat_history_rec record;
  found_flag boolean;
  history_pg_stat_activity_query text ; 
  query_text text ;
  activity_string text ; 
  
BEGIN
  RAISE NOTICE '***update_history_pg_stat_activity_by_queryid';
  
  result = TRUE ;
  
  FOR history_pg_stat_activity_rec IN 
  SELECT DISTINCT(query) AS query
  FROM activity_hist.history_pg_stat_activity
  WHERE queryid IS NULL
  LOOP
		history_pg_stat_activity_query = regexp_replace(history_pg_stat_activity_rec.query,'n+',' ','g');
		history_pg_stat_activity_query = regexp_replace(history_pg_stat_activity_query,'t+',' ','g');
		history_pg_stat_activity_query = regexp_replace(history_pg_stat_activity_query,' +',' ','g');
		history_pg_stat_activity_query = regexp_replace(history_pg_stat_activity_query,';','','g');
		query_text = trim(trailing ' ' from history_pg_stat_activity_query);
		
		FOR pg_stat_history_rec IN
		SELECT 
			queryid ,
			query 
		FROM 
			--pg_stat_history
			pg_stat_db_queries
		WHERE  
			queryid is not null 
		GROUP BY queryid ,	query 
		LOOP
			pg_stat_query = pg_stat_history_rec.query ; 
			pg_stat_query=regexp_replace(pg_stat_query,'n+',' ','g');
			pg_stat_query=regexp_replace(pg_stat_query,'t+',' ','g');
			pg_stat_query=regexp_replace(pg_stat_query,' +',' ','g');
			pg_stat_query=regexp_replace(pg_stat_query,'$.','%','g');	
			
			pg_stat_query_text = pg_stat_query; 
	  
			IF (query_text LIKE pg_stat_query_text) THEN
				found_flag = TRUE ;
			ELSE
				found_flag = FALSE ;
			END IF;	  
			
			IF found_flag 
			THEN
				UPDATE activity_hist.history_pg_stat_activity
				SET queryid = pg_stat_history_rec.queryid
				WHERE regexp_replace(regexp_replace(regexp_replace(regexp_replace(query,'n+',' ','g'),'t+',' ','g'),' +',' ','g'),';','','g') 
				      LIKE query_text||'%' ;
		
				activity_string = 	'history_pg_stat_activity has updated by queryid = '||pg_stat_history_rec.queryid;
				RAISE NOTICE '%',activity_string;	
				
				PERFORM pg_log( 999 , 'update_history_pg_stat_activity_by_queryid' , activity_string); 
				
				EXIT ;
				
			END IF ;	  
		END LOOP ;
		
		IF NOT found_flag 
		THEN
			activity_string = 'WARNING : Not FOUND queryid for the query : '||query_text ;
			
			RAISE NOTICE '%',activity_string;	
				
			PERFORM pg_log( 999 , 'update_history_pg_stat_activity_by_queryid' , activity_string); 
		END IF ;
		
	RAISE NOTICE 'UPDATE log_query if query has not logged in log-file';
		
  END LOOP;
  
  RETURN result ;
END
$$ LANGUAGE plpgsql;

Som tabellen inneholder verdien queryid som tilsvarer verdien queryid for forespørselen.

Resultat

Ved å sammenkoble pg_stat_activity, pg_stat_statements, log_query, kan man få mye nyttig informasjon om forespørselen, spesielt:

  • Historikken til utførelsesplanene.
  • Historikken til CPU-tiden for forespørselen.
  • Historikken til ventetidene for forespørselen.

Dataene og mange andre rapporter vil bli beskrevet i den neste artikkelen.

Utvikling

Ved å knytte informasjonen som er tilgjengelig med historien til pg_locks, kan man få informasjon om hvilken spesifikk lås forespørselen ventet på, og viktigst av alt, hvilken prosess (forespørsel) som holdt denne låsen.

Løsningen på dette problemet vil bli beskrevet i den følgende artikkelen. Testingen og forbedringen pågår nå.

Kilde: habr.com

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