学习目标
学习检查数据库运行状态、锁信息、维护表、重建索引等数据库维护操作技术
课程学习
1.检查openGauss状态
--操作系统命令查看实例状态
su - omm
ps -ef|grep gaussdb
omm 1 0 0 10:06 ? 00:00:11 gaussdb
omm 580 575 0 10:44 pts/0 00:00:00 grep gaussdb
ps -Tp 1
omm@modb:~$ ps -Tp 1
PID SPID TTY TIME CMD
1 1 ? 00:00:00 gaussdb
1 293 ? 00:00:00 jemalloc_bg_thd
1 299 ? 00:00:00 gaussdb
1 300 ? 00:00:00 syslogger
1 301 ? 00:00:00 jemalloc_bg_thd
1 302 ? 00:00:00 alarm
1 303 ? 00:00:00 reaper
1 304 ? 00:00:00 jemalloc_bg_thd
1 305 ? 00:00:00 jemalloc_bg_thd
1 350 ? 00:00:00 Spbgwriter
1 349 ? 00:00:00 checkpointer
1 352 ? 00:00:00 pagewriter
1 351 ? 00:00:01 pagewriter
1 353 ? 00:00:00 pagewriter
1 355 ? 00:00:00 pagewriter
1 354 ? 00:00:00 pagewriter
1 357 ? 00:00:00 WALwriteraux
1 356 ? 00:00:00 WALwriter
1 358 ? 00:00:00 AVClauncher
1 359 ? 00:00:00 Jobscheduler
1 360 ? 00:00:00 asyncundolaunch
1 361 ? 00:00:00 globalstats
1 363 ? 00:00:00 statscollector
1 362 ? 00:00:00 applylauncher
1 364 ? 00:00:01 percentworker
1 365 ? 00:00:04 ashworker
1 366 ? 00:00:01 TrackStmtWorker
1 367 ? 00:00:00 auditor
1 368 ? 00:00:00 2pccleaner
1 369 ? 00:00:00 faultmonitor
1 370 ? 00:00:00 WLMworker
1 371 ? 00:00:00 WLMmonitor
1 372 ? 00:00:00 WLMarbiter
1 373 ? 00:00:00 undorecycler
--使用数据库工具gs_ctl查看实例状态
omm@modb:~$ gs_ctl status -D /var/lib/opengauss/data
[2022-12-14 10:45:38.634][582][][gs_ctl]: gs_ctl status,datadir is /var/lib/opengauss/data
/usr/local/opengauss/bin/gaussdb
gs_ctl: server is running (PID: 1)
--检查参数
gsql -r
omm=# show data_directory ;
data_directory
-------------------------
/var/lib/opengauss/data
(1 row)
2.检查锁信息
锁机制是数据库保证数据一致性的重要手段，检查相关信息可以检查数据库的事务和运行状况。
--查询数据库中的锁信息
omm=# SELECT * FROM pg_locks;
locktype | database | relation | page | tuple | bucket | virtualxid | transactionid | classid | objid | objsubid | virtualt
ransaction | pid | sessionid | mode | granted | fastpath | locktag | global_sessionid
------------+----------+----------+------+-------+--------+------------+---------------+---------+-------+----------+--------------------+-----------------+-----------------+-----------------+---------+----------+-------------------+------------------
relation | 16384 | 12010 | | | | | | | | | 11/635 | 281472466189552 | 281472466189552 | AccessShareLock | t | t | 4000:2eea:0:0:0:0 | 0:0#0
virtualxid | | | | | | 11/635 | | | | | 11/635 | 281472466189552 | 281472466189552 | ExclusiveLock | t | t | b:27b:0:0:0:7 | 0:0#0
virtualxid | | | | | | 10/475 | | | | | 10/475 | 281471850151152 | 281471850151152 | ExclusiveLock | t | t | a:1db:0:0:0:7 | 0:0#0
(3 rows)
--查询等待锁的线程状态信息
omm=# SELECT * FROM pg_thread_wait_status WHERE wait_status = 'acquire lock';
-----------+---------+-------------+----------+-----+-----------+-------+------------+--------+-------+-------------+------------+---------+----------+-----------------+------------------
node_name | db_name | thread_name | query_id | tid | sessionid | lwtid | psessionid | tlevel | smpid | wait_status | wait_event | locktag | lockmode | block_sessionid | global_sessionid
(0 rows)
3.统计事件数据
SQL语句长时间运行会占用大量系统资源，用户可以通过查看事件发生的时间，占用内存大小来了解现在数据库运行状态。
--查询事件的时间，查询事件的线程启动时间、事务启动时间、SQL启动时间以及状态变更时间。
omm=# SELECT backend_start,xact_start,query_start,state_change FROM pg_stat_activity;
backend_start | xact_start | query_start | state_change
-------------------------------+-------------------------------+-------------------------------+-------------------------------
2022-12-14 10:45:54.642513+08 | 2022-12-14 10:47:38.840019+08 | 2022-12-14 10:47:38.840019+08 | 2022-12-14 10:47:38.840023+08
2022-12-14 10:06:47.521057+08 | 2022-12-14 10:06:47.523674+08 | 2022-12-14 10:06:47.523674+08 | 2022-12-14 10:06:47.523931+08
2022-12-14 10:06:47.521062+08 | | |
2022-12-14 10:06:47.520936+08 | | |
2022-12-14 10:06:47.518483+08 | | | 2022-12-14 10:06:47.518506+08
2022-12-14 10:06:47.518479+08 | | | 2022-12-14 10:47:38.807844+08
2022-12-14 10:06:47.518496+08 | | | 2022-12-14 10:47:29.982516+08
2022-12-14 10:06:47.518489+08 | | | 2022-12-14 10:47:38.092581+08
2022-12-14 10:06:47.509349+08 | | |
(9 rows)
--查询当前服务器的会话计数信息
SELECT count(*) FROM pg_stat_activity;
--查询系统级统计信息，查询当前使用内存最多的会话信息。
SELECT * FROM pv_session_memory_detail() ORDER BY usedsize desc limit 10;
--查询表统计信息
omm=# SELECT count(*) FROM pg_stat_activity;
count
-------
9
(1 row)
4.数据库版本、日志信息
--数据库版本
SELECT version();
version
-------------------------------------------------------------------------------------------------------------------------------------------------------
(openGauss 3.0.0 build 02c14696) compiled at 2022-04-01 18:12:00 commit 0 last mr on aarch64-unknown-linux-gnu, compiled by g++ (GCC) 7.3.0, 64-bit
(1 row)
--在gsql中
omm=# \! ls /var/lib/opengauss/data/pg_log
postgresql-2022-12-14_100636.log postgresql-2022-12-14_100647.log
\q
--数据库日志位置
omm@modb:~$ cd /var/lib/opengauss/data/pg_log
omm@modb:/var/lib/opengauss/data/pg_log$ ls -ltr
total 104
-rw------- 1 omm omm 26124 Dec 14 10:06 postgresql-2022-12-14_100636.log
-rw------- 1 omm omm 72766 Dec 14 10:48 postgresql-2022-12-14_100647.log
5.检查应用连接数
如果应用程序与数据库的连接数超过最大值，则新的连接无法建立。建议每天检查连接数，及时释放空闲的连接或者增加最大连接数。
--执行如下SQL语句查看连接数。
gsql -r
omm=# SELECT count(*) FROM (SELECT pg_stat_get_backend_idset() AS backendid) AS s;
count
-------
21
(1 row)
--查看现有最大连接数。
omm=# SHOW max_connections;
max_connections
-----------------
200
(1 row)
6.例行维护表：VACUUM、VACUUM FULL和ANALYZE
为了保证数据库的有效运行，数据库必须在插入/删除操作后，基于客户场景，定期做VACUUM FULL和ANALYZE，更新统计信息，以便获得更优的性能。
VACUUM和ANALYZE会导致I/O流量的大幅增加，这可能会影响其他活动会话的性能。
--创建表、插入数据、查看数据
CREATE TABLE customer_t
( c_customer_sk integer,
c_customer_id char(5),
c_first_name char(6),
c_last_name char(8)
) ;
INSERT INTO customer_t (c_customer_sk, c_customer_id, c_first_name,c_last_name) VALUES
(6885, 1, 'Joes', 'Hunter'),
(4321, 2, 'Lily','Carter'),
(9527, 3, 'James', 'Cook'),
(9500, 4, 'Lucy', 'Baker');
omm=# select count(*) from customer_t;
count
-------
4
(1 row)
--使用VACUUM或VACUUM FULL命令，进行磁盘空间回收。
--使用VACUUM
omm=# VACUUM customer_t;
VACUUM
--使用VACUUM full
--需要向正在执行的表增加排他锁，且需要停止其他所有数据库操作。
omm=# VACUUM FULL customer_t;
VACUUM
--使用ANALYZE语句更新统计信息。
omm=# ANALYZE customer_t;
ANALYZE
--使用ANALYZE VERBOSE语句更新统计信息，并输出表的相关信息。
omm=# ANALYZE VERBOSE customer_t;
INFO: analyzing "public.customer_t"(gaussdb pid=1)
INFO: ANALYZE INFO : "customer_t": scanned 1 of 1 pages, containing 4 live rows and 0 dead rows; 4 rows in sample, 4 estimated total rows(gaussdb pid=1)
ANALYZE
--也可以同时执行VACUUM ANALYZE命令进行查询优化。
omm=# VACUUM ANALYZE customer_t;
VACUUM
维护建议：
-
定期对部分大表做VACUUM FULL，在性能下降后为全库做VACUUM FULL，目前暂定每月做一次VACUUM FULL。
-
定期对系统表做VACUUM FULL，主要是PG_ATTRIBUTE。
-
启用系统自动清理线程（AUTOVACUUM）自动执行VACUUM和ANALYZE，回收被标识为删除状态的记录空间，并更新表的统计数据。
7.重建索引
在重建索引前，用户可以通过临时增大maintenance_work_mem和psort_work_mem的取值来加快索引的重建。
--环境准备
omm=# CREATE TABLESPACE EXAMPLE RELATIVE LOCATION 'tablespace1/tablespace_1';
CREATE TABLESPACE
omm=# CREATE schema HR;
CREATE SCHEMA
omm=# CREATE TABLE HR.areaS( area_ID NUMBER, area_NAME VARCHAR2(25) )tablespace EXAMPLE;
CREATE TABLE
omm=# \d HR.areaS
Table "hr.areas"
Column | Type | Modifiers
-----------+-----------------------+-----------
area_id | numeric |
area_name | character varying(25) |
Tablespace: "example"
omm=# CREATE INDEX areaS_idx ON HR.areaS (area_id);
CREATE INDEX
--使用REINDEX TABLE语句重建索引。
omm=# REINDEX table HR.areaS;
REINDEX
课程作业
1、使用操作系统命令和数据库工具检查实例状态
omm@modb:/var/lib/opengauss/data/pg_log$ ps -ef|grep gaussdb
omm 1 0 0 10:06 ? 00:00:14 gaussdb
omm 654 575 0 10:56 pts/0 00:00:00 grep gaussdb
omm@modb:~$ gs_ctl status
[2022-12-14 10:57:17.958][660][][gs_ctl]: gs_ctl status,datadir is /var/lib/opengauss/data
gs_ctl: server is running (PID: 1)
/usr/local/opengauss/bin/gaussdb2、检查锁信息
gsql -r
omm=# SELECT * FROM pg_locks;
locktype | database | relation | page | tuple | bucket | virtualxid | transactionid | classid | objid | objsubid | virtualt
ransaction | pid | sessionid | mode | granted | fastpath | locktag | global_sessionid
------------+----------+----------+------+-------+--------+------------+---------------+---------+-------+----------+--------------------+-----------------+-----------------+-----------------+---------+----------+-------------------+------------------
relation | 16384 | 12010 | | | | | | | | | 11/742 | 281471592725744 | 281471592725744 | AccessShareLock | t | t | 4000:2eea:0:0:0:0 | 0:0#0
virtualxid | | | | | | 11/742 | | | | | 11/742 | 281471592725744 | 281471592725744 | ExclusiveLock | t | t | b:2e6:0:0:0:7 | 0:0#0
virtualxid | | | | | | 10/614 | | | | | 10/614 | 281471850151152 | 281471850151152 | ExclusiveLock | t | t | a:266:0:0:0:7 | 0:0#0
(3 rows)
3、查看数据库版本、日志信息
omm=# select version();
version
-------------------------------------------------------------------------------------------------------------------------------------------------------
(openGauss 3.0.0 build 02c14696) compiled at 2022-04-01 18:12:00 commit 0 last mr on aarch64-unknown-linux-gnu, compiled by g++ (GCC) 7.3.0, 64-bit
(1 row)
omm=# show log_directory ;
log_directory
---------------
pg_log
(1 row)
omm=# \! ls /var/lib/opengauss/data/pg_log
postgresql-2022-12-14_100636.log postgresql-2022-12-14_100647.log4、检查应用连接数、查看现有最大连接数
omm=# SELECT count(*) FROM (SELECT pg_stat_get_backend_idset() AS backendid) AS s;
count
-------
21
(1 row)
omm=# show max_connections ;
max_connections
-----------------
200
(1 row)
5、对表进行VACUUM、VACUUM FULL和ANALYZE操作
CREATE TABLE DEPT
(DEPTNO int CONSTRAINT PK_DEPT PRIMARY KEY,
DNAME VARCHAR(14) ,
LOC VARCHAR(13) ) ;
CREATE TABLE EMP
(EMPNO int CONSTRAINT PK_EMP PRIMARY KEY,
ENAME varchar(10),
JOB varchar(9),
MGR int,
HIREDATE DATE,
SAL int,
COMM int,
DEPTNO int CONSTRAINT FK_DEPTNO REFERENCES DEPT);
INSERT INTO DEPT VALUES
(10,'ACCOUNTING','NEW YORK');
INSERT INTO DEPT VALUES (20,'RESEARCH','DALLAS');
INSERT INTO DEPT VALUES
(30,'SALES','CHICAGO');
INSERT INTO DEPT VALUES
(40,'OPERATIONS','BOSTON');
INSERT INTO EMP VALUES
(7369,'SMITH','CLERK',7902,to_date('17-12-1980','dd-mm-yyyy'),800,NULL,20);
INSERT INTO EMP VALUES
(7499,'ALLEN','SALESMAN',7698,to_date('20-2-1981','dd-mm-yyyy'),1600,300,30);
INSERT INTO EMP VALUES
(7521,'WARD','SALESMAN',7698,to_date('22-2-1981','dd-mm-yyyy'),1250,500,30);
INSERT INTO EMP VALUES
(7566,'JONES','MANAGER',7839,to_date('2-4-1981','dd-mm-yyyy'),2975,NULL,20);
INSERT INTO EMP VALUES
(7654,'MARTIN','SALESMAN',7698,to_date('28-9-1981','dd-mm-yyyy'),1250,1400,30);
INSERT INTO EMP VALUES
(7698,'BLAKE','MANAGER',7839,to_date('1-5-1981','dd-mm-yyyy'),2850,NULL,30);
INSERT INTO EMP VALUES
(7782,'CLARK','MANAGER',7839,to_date('9-6-1981','dd-mm-yyyy'),2450,NULL,10);
INSERT INTO EMP VALUES
(7788,'SCOTT','ANALYST',7566,to_date('13-JUL-87','dd-mm-rr')-85,3000,NULL,20);
INSERT INTO EMP VALUES
(7839,'KING','PRESIDENT',NULL,to_date('17-11-1981','dd-mm-yyyy'),5000,NULL,10);
INSERT INTO EMP VALUES
(7844,'TURNER','SALESMAN',7698,to_date('8-9-1981','dd-mm-yyyy'),1500,0,30);
INSERT INTO EMP VALUES
(7876,'ADAMS','CLERK',7788,to_date('13-JUL-87', 'dd-mm-rr')-51,1100,NULL,20);
INSERT INTO EMP VALUES
(7900,'JAMES','CLERK',7698,to_date('3-12-1981','dd-mm-yyyy'),950,NULL,30);
INSERT INTO EMP VALUES
(7902,'FORD','ANALYST',7566,to_date('3-12-1981','dd-mm-yyyy'),3000,NULL,20);
INSERT INTO EMP VALUES
(7934,'MILLER','CLERK',7782,to_date('23-1-1982','dd-mm-yyyy'),1300,NULL,10);
omm=# vacuum emp;
VACUUM
omm=# vacuum FULL emp ;
omm=# VACUUM
omm=# analyze emp ;
ANALYZE
6、建表、索引，进行重建索引操作
omm=# CREATE TABLE EMP
(EMPNO int CONSTRAINT PK_EMP PRIMARY KEY,
ENAME varchar(10),
JOB varchar(9),
MGR int,
HIREDATE DATE,
SAL int,
COMM int,
DEPTNO int CONSTRAINT FK_DEPTNO REFERENCES DEPT);
omm=# create index idx_name on emp(ename);
CREATE INDEX
omm=# reindex index idx_name ;
omm=# REINDEX
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