课程学习
1.检查openGauss状态
–操作系统命令查看实例状态
root@modb:~# su - omm
omm@modb:~$ ps -ef|grep gaussdb
omm 1 0 0 11:04 ? 00:00:00 bash /usr/local/bin/entrypoint.sh gaussdb
omm 211 1 10 11:04 ? 00:00:00 /usr/local/opengauss/bin/gaussdb -D /var/lib/opengauss/data -c listen_addresses= -p 5432
omm 298 167 0 11:04 pts/0 00:00:00 grep gaussdb
omm@modb:~$ ps -Tp 1
PID SPID TTY TIME CMD
1 1 ? 00:00:00 gaussdb
1 299 ? 00:00:00 jemalloc_bg_thd
1 305 ? 00:00:00 gaussdb
1 306 ? 00:00:00 syslogger
1 307 ? 00:00:00 jemalloc_bg_thd
1 308 ? 00:00:00 alarm
1 309 ? 00:00:00 reaper
1 310 ? 00:00:00 jemalloc_bg_thd
1 311 ? 00:00:00 jemalloc_bg_thd
1 355 ? 00:00:00 checkpointer
1 356 ? 00:00:00 Spbgwriter
1 357 ? 00:00:00 pagewriter
1 358 ? 00:00:00 pagewriter
1 359 ? 00:00:00 pagewriter
1 361 ? 00:00:00 pagewriter
1 360 ? 00:00:00 pagewriter
1 362 ? 00:00:00 WALwriter
1 363 ? 00:00:00 WALwriteraux
1 364 ? 00:00:00 AVClauncher
1 365 ? 00:00:00 Jobscheduler
1 366 ? 00:00:00 asyncundolaunch
1 367 ? 00:00:00 globalstats
1 368 ? 00:00:00 applylauncher
1 369 ? 00:00:00 statscollector
1 370 ? 00:00:00 percentworker
1 372 ? 00:00:00 TrackStmtWorker
1 371 ? 00:00:00 ashworker
1 373 ? 00:00:00 auditor
1 374 ? 00:00:00 2pccleaner
1 375 ? 00:00:00 faultmonitor
1 376 ? 00:00:00 WLMworker
1 377 ? 00:00:00 WLMmonitor
1 378 ? 00:00:00 WLMarbiter
1 379 ? 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 11:06:14.152][386][][gs_ctl]: gs_ctl status,datadir is /var/lib/opengauss/data
gs_ctl: server is running (PID: 1)
/usr/local/opengauss/bin/gaussdb
–检查参数
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;
(1 row)
omm=# data_directory
-------------------------
/var/lib/opengauss/data
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 | virtualtransaction | pid | sessioni
d | mode | granted | fastpath | locktag | global_sessionid
------------+----------+----------+------+-------+--------+------------+---------------+---------+-------+----------+--------------------+-----------------+------------
-----+-----------------+---------+----------+-------------------+------------------
relation | 16384 | 12010 | | | | | | | | | 11/24 | 281471219432688 | 28147121943
2688 | AccessShareLock | t | t | 4000:2eea:0:0:0:0 | 0:0#0
virtualxid | | | | | | 11/24 | | | | | 11/24 | 281471219432688 | 28147121943
2688 | ExclusiveLock | t | t | b:18:0:0:0:7 | 0:0#0
virtualxid | | | | | | 9/27 | | | | | 9/27 | 281471385107696 | 28147138510
7696 | ExclusiveLock | t | t | 9:1b: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';
-----------+---------+-------------+----------+-----+-----------+-------+------------+--------+-------+-------------+------------+---------+----------+-----------------
+------------------
(0 rows)
node_name | db_name | thread_name | query_id | tid | sessionid | lwtid | psessionid | tlevel | smpid | wait_status | wait_event | locktag | lockmode | block_sessionid
| global_sessionid
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 11:06:37.90438+08 | 2022-12-14 11:08:32.233157+08 | 2022-12-14 11:08:32.233157+08 | 2022-12-14 11:08:32.233162+08
2022-12-14 11:05:05.110146+08 | | |
2022-12-14 11:05:05.109921+08 | 2022-12-14 11:05:05.111307+08 | 2022-12-14 11:05:05.111307+08 | 2022-12-14 11:05:05.111557+08
2022-12-14 11:05:05.109881+08 | | |
2022-12-14 11:05:05.107214+08 | | | 2022-12-14 11:08:31.621024+08
2022-12-14 11:05:05.107239+08 | | | 2022-12-14 11:08:25.309185+08
2022-12-14 11:05:05.097774+08 | | |
2022-12-14 11:05:05.107233+08 | | | 2022-12-14 11:05:05.10725+08
2022-12-14 11:05:05.107232+08 | | | 2022-12-14 11:08:31.306096+08
(9 rows)
–查询当前服务器的会话计数信息
omm=# SELECT count(*) FROM pg_stat_activity;
count
-------
9
(1 row)
–查询系统级统计信息，查询当前使用内存最多的会话信息。
omm=# SELECT * FROM pv_session_memory_detail() ORDER BY usedsize desc limit 10;
sessid | threadid | contextname | level | parent | totalsize | freesize | usedsize
--------+----------+-------------+-------+--------+-----------+----------+----------
(0 rows)
–查询表统计信息
omm=# SELECT * FROM pg_statistic;
starelid | starelkind | staattnum | stainherit | stanullfrac | stawidth | stadistinct | stakind1 | stakind2 | stakind3 | stakind4 | stakind5 | staop1 | staop2 | staop3
| staop4 | staop5 |
stanumbers1
| stanumbers2 |
4.数据库版本、日志信息
–数据库版本
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)
–在gsql中
omm=# \! ls /var/lib/opengauss/data/pg_log
postgresql-2022-12-14_110453.log postgresql-2022-12-14_110504.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$
omm@modb:~$ ls /var/lib/opengauss/data/pg_log
postgresql-2022-12-14_110453.log postgresql-2022-12-14_110504.log
omm@modb:/var/lib/opengauss/data/pg_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;
omm=# 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
omm=# CREATE TABLE customer_t
omm-# ( c_customer_sk integer,
omm-# ( c_customer_id char(5),
c_first_name char(6),
omm-#( c_last_name char(8)
omm-#( ) ;
CREATE TABLE
omm-#INSERT INTO customer_t (c_customer_sk, c_customer_id, c_first_name,c_last_name) VALUES
(6885, 1, 'Joes', 'Hunter'),
omm-# (4321, 2, 'Lily','Carter'),
omm-# (9527, 3, 'James', 'Cook'),
omm-# (9500, 4, 'Lucy', 'Baker');
INSERT 0 4
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:~$ ps -ef|grep gaussdb
omm 1 0 0 11:04 ? 00:00:00 bash /usr/local/bin/entrypoint.sh gaussdb
omm 211 1 10 11:04 ? 00:00:00 /usr/local/opengauss/bin/gaussdb -D /var/lib/opengauss/data -c listen_addresses= -p 5432
omm 298 167 0 11:04 pts/0 00:00:00 grep gaussdb
omm@modb:~$ gs_ctl status -D /var/lib/opengauss/data
[2022-12-14 11:06:14.152][386][][gs_ctl]: gs_ctl status,datadir is /var/lib/opengauss/data
gs_ctl: server is running (PID: 1)
/usr/local/opengauss/bin/gaussdb
2、检查锁信息
omm=# select * from pg_locks;
locktype | database | relation | page | tuple | bucket | virtualxid | transactionid | classid | objid | objsubid | virtualtransaction | pid | sessioni
d | mode | granted | fastpath | locktag | global_sessionid
------------+----------+----------+------+-------+--------+------------+---------------+---------+-------+----------+--------------------+-----------------+------------
-----+-----------------+---------+----------+-------------------+------------------
relation | 16384 | 12010 | | | | | | | | | 11/89 | 281471219432688 | 28147121943
2688 | AccessShareLock | t | t | 4000:2eea:0:0:0:0 | 0:0#0
virtualxid | | | | | | 11/89 | | | | | 11/89 | 281471219432688 | 28147121943
2688 | ExclusiveLock | t | t | b:59:0:0:0:7 | 0:0#0
virtualxid | | | | | | 9/233 | | | | | 9/233 | 281471385107696 | 28147138510
7696 | ExclusiveLock | t | t | 9:e9:0:0:0:7 | 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=# \! ls /var/lib/opengauss/data/pg_log
postgresql-2022-12-14_110453.log postgresql-2022-12-14_110504.log
4、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
omm=# VACUUM customer_t;
VACUUM
omm=# VACUUM FULL customer_t;
VACUUM
omm=# VACUUM ANALYZE customer_t;
VACUUM
6、建表、索引，进行重建索引操作
omm=# CREATE TABLE course
omm-# (
omm(# cor_id INT PRIMARY KEY,
omm(# cor_name VARCHAR(30) NOT NULL,
omm(# cor_type VARCHAR(20),
omm(# credit DOUBLE PRECISION
omm(# );
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "course_pkey" for table "course"
CREATE TABLE
omm=# create index ndx_course_name on course(cor_name);
CREATE INDEX
omm=# \di
List of relations
Schema | Name | Type | Owner | Table | Storage
--------+-----------------+-------+-------+--------+---------
public | course_pkey | index | omm | course |
public | ndx_course_name | index | omm | course |
(2 rows)
omm=# reindex table course;
REINDEX
omm=# \di+
List of relations
Schema | Name | Type | Owner | Table | Size | Storage | Description
--------+-----------------+-------+-------+--------+------------+---------+-------------
public | course_pkey | index | omm | course | 8192 bytes | |
public | ndx_course_name | index | omm | course | 8192 bytes | |
(2 rows)
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