课程学习内容
软件版本 ：openGauss 3.0.0
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。
数据库实操内容
环境准备
–操作系统命令查看实例状态
su - omm
ps -ef|grep gaussdb
ps -Tp 1
root@modb:~# su - omm
omm=# \q
omm@modb:~$ ps -ef|grep gaussdb
omm 1 0 0 20:09 ? 00:00:24 gaussdb
omm 803 797 0 21:49 pts/0 00:00:00 grep gaussdb
omm@modb:~$ ps -Tp 1
PID SPID TTY TIME CMD
1 1 ? 00:00:00 gaussdb
1 294 ? 00:00:00 jemalloc_bg_thd
1 300 ? 00:00:00 gaussdb
1 301 ? 00:00:00 syslogger
1 302 ? 00:00:00 jemalloc_bg_thd
1 303 ? 00:00:00 alarm
1 304 ? 00:00:00 reaper
1 305 ? 00:00:00 jemalloc_bg_thd
1 306 ? 00:00:00 jemalloc_bg_thd
1 350 ? 00:00:00 checkpointer
1 351 ? 00:00:00 Spbgwriter
1 352 ? 00:00:00 pagewriter
1 353 ? 00:00:03 pagewriter
1 358 ? 00:00:00 WALwriteraux
1 359 ? 00:00:00 AVClauncher
1 360 ? 00:00:00 Jobscheduler
1 361 ? 00:00:00 asyncundolaunch
1 362 ? 00:00:00 globalstats
1 363 ? 00:00:00 applylauncher
1 354 ? 00:00:00 pagewriter
1 355 ? 00:00:00 pagewriter
1 356 ? 00:00:00 pagewriter
1 357 ? 00:00:00 WALwriter
1 364 ? 00:00:00 statscollector
1 365 ? 00:00:02 percentworker
1 366 ? 00:00:10 ashworker
1 367 ? 00:00:02 TrackStmtWorker
1 368 ? 00:00:00 auditor
1 369 ? 00:00:00 2pccleaner
1 370 ? 00:00:00 faultmonitor
1 371 ? 00:00:00 WLMworker
1 372 ? 00:00:00 WLMmonitor
1 373 ? 00:00:00 WLMarbiter
1 374 ? 00:00:00 undorecycler
omm@modb:~$
–使用数据库工具gs_ctl查看实例状态
gs_ctl status -D /var/lib/opengauss/data
omm@modb:~$ gs_ctl status -D /var/lib/opengauss/data
[2022-12-14 21:49:39.985][810][][gs_ctl]: gs_ctl status,datadir is /var/lib/opengauss/data
gs_ctl: server is running (PID: 1)
/usr/local/opengauss/bin/gaussdb
omm@modb:~$
–检查参数
gsql -r
show data_directory;
omm@modb:~$ gsql -r
gsql ((openGauss 3.0.0 build 02c14696) compiled at 2022-04-01 18:12:00 commit 0 last mr )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.
omm=# show data_directory;
data_directory
-------------------------
/var/lib/opengauss/data
(1 row)
omm=#
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
SELECT * FROM pg_locks;
omm=# SELECT * FROM pg_locks;
---------+--------------------+-----------------+-----------------+-----------------+---------+----------+-
------------------+------------------
relation | 16384 | 12010 | | | | | | | |
| 11/1652 | 281470802099440 | 281470802099440 | AccessShareLock | t | t |
4000:2eea:0:0:0:0 | 0:0#0
virtualxid | | | | | | 11/1652 | | | |
| 11/1652 | 281470802099440 | 281470802099440 | ExclusiveLock | t | t |
b:674:0:0:0:7 | 0:0#0
virtualxid | | | | | | 10/1211 | | | |
locktype | database | relation | page | tuple | bucket | virtualxid | transactionid | classid | objid |
objsubid | virtualtransaction | pid | sessionid | mode | granted | fastpath |
locktag | global_sessionid
------------+----------+----------+------+-------+--------+------------+---------------+---------+-------+-
| 10/1211 | 281470983503088 | 281470983503088 | ExclusiveLock | t | t |
a:4bb:0:0:0:7 | 0:0#0
(3 rows)
omm=#
–查询等待锁的线程状态信息
SELECT * FROM pg_thread_wait_status WHERE wait_status = ‘acquire lock’;
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 | wai
t_status | wait_event | locktag | lockmode | block_sessionid | global_sessionid
-----------+---------+-------------+----------+-----+-----------+-------+------------+--------+-------+----
---------+------------+---------+----------+-----------------+------------------
(0 rows)
omm=#
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。
SELECT backend_start,xact_start,query_start,state_change FROM pg_stat_activity;
omm=# SELECT backend_start,xact_start,query_start,state_change FROM pg_stat_activity;
backend_start | xact_start | query_start | st
ate_change
-------------------------------+-------------------------------+-------------------------------+-----------
--------------------
2022-12-14 21:49:52.267305+08 | 2022-12-14 21:51:04.095449+08 | 2022-12-14 21:51:04.095449+08 | 2022-12-14
21:51:04.095454+08
2022-12-14 20:09:28.286942+08 | 2022-12-14 20:09:28.291124+08 | 2022-12-14 20:09:28.291124+08 | 2022-12-14
20:09:28.29134+08
2022-12-14 20:09:28.287057+08 | | |
2022-12-14 20:09:28.287039+08 | | |
2022-12-14 20:09:28.287818+08 | | | 2022-12-14
21:50:54.426262+08
2022-12-14 20:09:28.28784+08 | | | 2022-12-14
21:51:03.555025+08
2022-12-14 20:09:28.27559+08 | | |
2022-12-14 20:09:28.287822+08 | | | 2022-12-14
20:09:28.287839+08
2022-12-14 20:09:28.287837+08 | | | 2022-12-14
21:51:04.010394+08
(9 rows)
omm=#
–查询当前服务器的会话计数信息
SELECT count(*) FROM pg_stat_activity;
omm=# SELECT count(*) FROM pg_stat_activity;
count
-------
9
(1 row)
omm=#
–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;
omm=# SELECT * FROM pv_session_memory_detail() ORDER BY usedsize desc limit 10;
sessid | threadid | contextname | level | parent | totalsize | freesize | usedsize
--------+----------+-------------+-------+--------+-----------+----------+----------
(0 rows)
omm=#
–查询表统计信息
SELECT * FROM pg_statistic;
omm=# SELECT count(*) FROM pg_stat_activity;
count
-------
9
(1 row)
omm=# SELECT * FROM pv_session_memory_detail() ORDER BY usedsize desc limit 10;
sessid | threadid | contextname | level | parent | totalsize | freesize | usedsize
--------+----------+-------------+-------+--------+-----------+----------+----------
(0 rows)
omm=# SELECT * FROM pg_statistic;
starelid | starelkind | staattnum | stainherit | stanullfrac | stawidth | stadistinct | stakind1 | stakind
2 | stakind3 | stakind4 | stakind5 | staop1 | staop2 | staop3 | staop4 | staop5 |
stanumbers1
| stanumbers2 |
omm=#
数据库版本、日志信息
–数据库版本
SELECT version();
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-lin
ux-gnu, compiled by g++ (GCC) 7.3.0, 64-bit
(1 row)
omm=#
–在gsql中
! ls /var/lib/opengauss/data/pg_log
\q
omm=# \! ls /var/lib/opengauss/data/pg_log
postgresql-2022-12-14_200916.log postgresql-2022-12-14_200928.log
omm=# \q
omm@modb:~$
–数据库日志位置
cd /var/lib/opengauss/data/pg_log
ls /var/lib/opengauss/data/pg_log
omm@modb:~$ cd /var/lib/opengauss/data/pg_log
omm@modb:/var/lib/opengauss/data/pg_log$ ls /var/lib/opengauss/data/pg_log
postgresql-2022-12-14_200916.log postgresql-2022-12-14_200928.log
omm@modb:/var/lib/opengauss/data/pg_log$
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
SELECT count(*) FROM (SELECT pg_stat_get_backend_idset() AS backendid) AS s;
omm@modb:/var/lib/opengauss/data/pg_log$ gsql -r
gsql ((openGauss 3.0.0 build 02c14696) compiled at 2022-04-01 18:12:00 commit 0 last mr )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.
omm=# SELECT count(*) FROM (SELECT pg_stat_get_backend_idset() AS backendid) AS s;
count
-------
21
(1 row)
omm=#
–查看现有最大连接数。
SHOW max_connections;
omm=# SHOW max_connections;
max_connections
-----------------
200
(1 row)
omm=#
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’); select count(*) from customer_t;
omm=# CREATE TABLE customer_t
omm-# ( c_customer_sk integer,
omm(# c_customer_id char(5),
omm(# c_first_name char(6),
omm(# c_last_name char(8)
omm(# ) ;
CREATE TABLE
omm=#
omm=# INSERT INTO customer_t (c_customer_sk, c_customer_id, c_first_name,c_last_name) VALUES
omm-# (6885, 1, 'Joes', 'Hunter'),
omm-# (4321, 2, 'Lily','Carter'),
omm-# (9527, 3, 'James', 'Cook'),
omm-# (9500, 4, 'Lucy', 'Baker');
INSERT 0 4
omm=#
omm=# select count(*) from customer_t;
count
-------
4
(1 row)
omm=#
–使用VACUUM或VACUUM FULL命令，进行磁盘空间回收。
–使用VACUUM
VACUUM customer_t;
omm=# VACUUM customer_t;
VACUUM
omm=#
–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。
VACUUM FULL customer_t;
omm=# VACUUM FULL customer_t;
VACUUM
omm=#
–使用ANALYZE语句更新统计信息。
ANALYZE customer_t;
omm=# ANALYZE customer_t;
ANALYZE
omm=#
–使用ANALYZE VERBOSE语句更新统计信息，并输出表的相关信息。
ANALYZE VERBOSE customer_t;
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
omm=#
–也可以同时执行VACUUM ANALYZE命令进行查询优化。
VACUUM ANALYZE customer_t;
omm=# VACUUM ANALYZE customer_t;
VACUUM
omm=#
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。
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
CREATE TABLESPACE EXAMPLE RELATIVE LOCATION ‘tablespace1/tablespace_1’;
CREATE schema HR;
CREATE TABLE HR.areaS( area_ID NUMBER, area_NAME VARCHAR2(25) )tablespace EXAMPLE; \d HR.areaS CREATE INDEX areaS_idx ON HR.areaS (area_id);
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
omm=#
–使用REINDEX TABLE语句重建索引。
REINDEX table HR.areaS;
omm=# REINDEX table HR.areaS;
REINDEX
omm=#
课程作业
使用操作系统命令和数据库工具检查实例状态
root@modb:~# su - omm
omm=# \q
omm@modb:~$ ps -ef|grep gaussdb
omm 1 0 0 20:09 ? 00:00:24 gaussdb
omm 803 797 0 21:49 pts/0 00:00:00 grep gaussdb
omm@modb:~$ ps -Tp 1
PID SPID TTY TIME CMD
1 1 ? 00:00:00 gaussdb
1 294 ? 00:00:00 jemalloc_bg_thd
1 300 ? 00:00:00 gaussdb
1 301 ? 00:00:00 syslogger
1 302 ? 00:00:00 jemalloc_bg_thd
1 303 ? 00:00:00 alarm
1 304 ? 00:00:00 reaper
1 305 ? 00:00:00 jemalloc_bg_thd
1 306 ? 00:00:00 jemalloc_bg_thd
1 350 ? 00:00:00 checkpointer
1 351 ? 00:00:00 Spbgwriter
1 352 ? 00:00:00 pagewriter
1 353 ? 00:00:03 pagewriter
1 358 ? 00:00:00 WALwriteraux
1 359 ? 00:00:00 AVClauncher
1 360 ? 00:00:00 Jobscheduler
1 361 ? 00:00:00 asyncundolaunch
1 362 ? 00:00:00 globalstats
1 363 ? 00:00:00 applylauncher
1 354 ? 00:00:00 pagewriter
1 355 ? 00:00:00 pagewriter
1 356 ? 00:00:00 pagewriter
1 357 ? 00:00:00 WALwriter
1 364 ? 00:00:00 statscollector
1 365 ? 00:00:02 percentworker
1 366 ? 00:00:10 ashworker
1 367 ? 00:00:02 TrackStmtWorker
1 368 ? 00:00:00 auditor
1 369 ? 00:00:00 2pccleaner
1 370 ? 00:00:00 faultmonitor
1 371 ? 00:00:00 WLMworker
1 372 ? 00:00:00 WLMmonitor
1 373 ? 00:00:00 WLMarbiter
1 374 ? 00:00:00 undorecycler
omm@modb:~$
omm@modb:~$ gs_ctl status -D /var/lib/opengauss/data
[2022-12-14 21:49:39.985][810][][gs_ctl]: gs_ctl status,datadir is /var/lib/opengauss/data
gs_ctl: server is running (PID: 1)
/usr/local/opengauss/bin/gaussdb
omm@modb:~$
检查锁信息
omm=# SELECT * FROM pg_locks;
locktype | database | relation | page | tuple | bucket | virtualxid | transactionid | classid | objid |
objsubid | virtualtransaction | pid | sessionid | mode | granted | fastpath |
locktag | global_sessionid
------------+----------+----------+------+-------+--------+------------+---------------+---------+-------+-
---------+--------------------+-----------------+-----------------+-----------------+---------+----------+-
------------------+------------------
relation | 16384 | 12010 | | | | | | | |
| 11/1718 | 281470762253552 | 281470762253552 | AccessShareLock | t | t |
4000:2eea:0:0:0:0 | 0:0#0
virtualxid | | | | | | 11/1718 | | | |
| 11/1718 | 281470762253552 | 281470762253552 | ExclusiveLock | t | t |
b:6b6:0:0:0:7 | 0:0#0
virtualxid | | | | | | 10/1369 | | | |
| 10/1369 | 281470983503088 | 281470983503088 | ExclusiveLock | t | t |
a:559:0:0:0:7 | 0:0#0
(3 rows)
omm=#
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 | wai
t_status | wait_event | locktag | lockmode | block_sessionid | global_sessionid
-----------+---------+-------------+----------+-----+-----------+-------+------------+--------+-------+----
---------+------------+---------+----------+-----------------+------------------
(0 rows)
omm=#
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-lin
ux-gnu, compiled by g++ (GCC) 7.3.0, 64-bit
(1 row)
omm=# \! ls /var/lib/opengauss/data/pg_log
postgresql-2022-12-14_200916.log postgresql-2022-12-14_200928.log
omm=#
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)
omm=#
对表进行VACUUM、VACUUM FULL和ANALYZE操作
omm=# VACUUM customer_t;
VACUUM
omm=# VACUUM FULL customer_t;
VACUUM
omm=# ANALYZE customer_t;
ANALYZE
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
omm=# VACUUM ANALYZE customer_t;
VACUUM
omm=#
建表、索引，进行重建索引操作
omm=# CREATE TABLESPACE EXAMPLE1 RELATIVE LOCATION 'tablespace1/tablespace_2';
CREATE TABLESPACE
omm=# CREATE schema HR1;
CREATE SCHEMA
omm=# CREATE TABLE HR1.areaS( area_ID NUMBER, area_NAME VARCHAR2(25) )tablespace EXAMPLE1;
CREATE TABLE
omm=# \d HR1.areaS
Table "hr1.areas"
Column | Type | Modifiers
-----------+-----------------------+-----------
area_id | numeric |
area_name | character varying(25) |
Tablespace: "example1"
omm=#
omm=# CREATE INDEX areaS_idx1 ON HR1.areaS (area_id);
CREATE INDEX
omm=# REINDEX table HR1.areaS;
REINDEX
omm=#
课程学习体会
通过本次的实训操作，掌握数据库的运行状态、锁信息、维护表、重建索引等数据库维护操作技术。
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