openGauss每日一练第21天 |数据库例行维护
openGauss数据库例行维护
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
root@modb:~# su - omm
omm@modb:~$
omm@modb:~$ ps -ef|grep gaussdb
omm 1 0 0 10:14 ? 00:00:02 gaussdb
omm 409 405 0 10:21 pts/0 00:00:00 grep gaussdb
omm@modb:~$ ps -Tp 1
PID SPID TTY TIME CMD
1 1 ? 00:00:00 gaussdb
1 287 ? 00:00:00 jemalloc_bg_thd
1 293 ? 00:00:00 gaussdb
1 296 ? 00:00:00 alarm
1 294 ? 00:00:00 syslogger
1 295 ? 00:00:00 jemalloc_bg_thd
1 297 ? 00:00:00 reaper
1 298 ? 00:00:00 jemalloc_bg_thd
1 299 ? 00:00:00 jemalloc_bg_thd
1 343 ? 00:00:00 checkpointer
1 344 ? 00:00:00 Spbgwriter
1 346 ? 00:00:00 pagewriter
1 347 ? 00:00:00 pagewriter
1 345 ? 00:00:00 pagewriter
1 348 ? 00:00:00 pagewriter
1 349 ? 00:00:00 pagewriter
1 350 ? 00:00:00 WALwriter
1 351 ? 00:00:00 WALwriteraux
1 352 ? 00:00:00 AVClauncher
1 353 ? 00:00:00 Jobscheduler
1 354 ? 00:00:00 asyncundolaunch
1 355 ? 00:00:00 globalstats
1 356 ? 00:00:00 applylauncher
1 357 ? 00:00:00 statscollector
1 358 ? 00:00:00 percentworker
1 359 ? 00:00:00 ashworker
1 360 ? 00:00:00 TrackStmtWorker
1 362 ? 00:00:00 2pccleaner
1 361 ? 00:00:00 auditor
1 363 ? 00:00:00 faultmonitor
1 364 ? 00:00:00 WLMworker
1 365 ? 00:00:00 WLMmonitor
1 366 ? 00:00:00 WLMarbiter
1 367 ? 00:00:00 undorecycler
omm@modb:~$
--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 10:21:27.462][412][][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
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@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=#
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 | | | | | | | | | 11/104 | 281471525616880 | 28147152561
6880 | AccessShareLock | t | t | 4000:2eea:0:0:0:0 | 0:0#0
virtualxid | | | | | | 11/104 | | | | | 11/104 | 281471525616880 | 28147152561
6880 | ExclusiveLock | t | t | b:68:0:0:0:7 | 0:0#0
virtualxid | | | | | | 9/74 | | | | | 9/74 | 281471700729072 | 28147170072
9072 | ExclusiveLock | t | t | 9:4a:0:0:0:7 | 0:0#0
(3 rows)
omm=#
--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 10:21:27.473332+08 | 2022-12-14 10:21:32.764844+08 | 2022-12-14 10:21:32.764844+08 | 2022-12-14 10:21:32.764849+08
2022-12-14 10:15:26.561088+08 | | |
2022-12-14 10:15:26.560986+08 | 2022-12-14 10:15:26.563996+08 | 2022-12-14 10:15:26.563996+08 | 2022-12-14 10:15:26.564212+08
2022-12-14 10:15:26.561107+08 | | |
2022-12-14 10:15:26.55762+08 | | | 2022-12-14 10:21:32.523912+08
2022-12-14 10:15:26.549443+08 | | |
2022-12-14 10:15:26.557639+08 | | | 2022-12-14 10:15:26.557664+08
omm=#
--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)
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。
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
omm=# SELECT * FROM pg_statistic limit 1;
starelid | starelkind | staattnum | stainherit | stanullfrac | stawidth | stadistinct | stakind1 | stakind2 | stakind3 | stakind4 | stakind5 | staop1 | staop2 | staop3
| staop4 | staop5 | stanumbers1 | stanumbers2 | stanumbers3 | stanumbers4 | stanumbers5 | stavalues1 |
stavalues2
| stavalues3 | stavalues4 | stavalues5 | stadndistinct | staexti
nfo
----------+------------+-----------+------------+-------------+----------+-------------+----------+----------+----------+----------+----------+--------+--------+-------
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-+--------+--------+-------------+-------------+-------------+-------------+-------------+---------------------+--------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------+------------+------------+------------+---------------+--------
----
1247 | c | 1 | f | 0 | 64 | -.998609 | 1 | 2 | 3 | 0 | 0 | 93 | 660 | 660
| 0 | 0 | {.00278164} | | {.254631} | | | {statement_history} | {TdigestData,_box,_cid,_float4,_hll_trans_type,_int2vec
tor_extend,_jsonb,_nvarchar2,_pg_foreign_tables,_regclass,_regtype,_timestamptz,_txid_snapshot,aclitem,anyrange,box,char,circle,column_privileges,date,exception,foreign
_data_wrappers,global_candidate_status,global_locks,global_pagewriter_status,global_replication_stat,global_shared_memory_detail,global_stat_database,global_stat_user_i
ndexes,global_statement_complex_history_table,global_statio_sys_sequences,global_threadpool_status,gs_auditing,gs_client_global_keys,gs_db_privileges,gs_global_config,g
s_masking,gs_model_warehouse,gs_session_cpu_statistics,gs_shared_memory_detail,gs_total_memory_detail,gs_wlm_ec_operator_statistics,gs_wlm_plan_operator_info,gs_wlm_ses
sion_statistics,hll_hashval,int16,int8range,line,memory_node_detail,nvarchar2,os_runtime,pg_amproc,pg_available_extension_versions,pg_comm_send_stream,pg_db_role_settin
g,pg_extension,pg_group,pg_job,pg_node_env,pg_os_threads,pg_publication_rel,pg_rewrite,pg_seclabels,pg_stat_activity,pg_stat_database_conflicts,pg_stat_user_tables,pg_s
tatio_all_tables,pg_statistic,pg_tde_info,pg_toast_12479,pg_toast_12554,pg_toast_13733,pg_toast_2619,pg_toast_5818,pg_total_user_resource_info,pg_type,pg_wlm_statistics
,pgxc_thread_wait_status,refcursor,regproc,role_routine_grants,sequences,shared_memory_detail,sql_implementation_info,stat_all_tables,stat_user_indexes,statement_comple
x_history,statio_all_indexes,statio_user_tables,summary_stat_all_indexes,summary_stat_user_functions,summary_statement,summary_statio_sys_tables,summary_workload_sql_co
unt,thread_wait_status,tinterval,tsrange,user_defined_types,varchar,wlm_user_resource_config,yes_or_no} | | | | 0 |
(1 row)
omm=#
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)
omm=#
--在gsql中
omm=# \! ls /var/lib/opengauss/data/pg_log
postgresql-2022-12-14_101515.log postgresql-2022-12-14_101526.log
omm=# \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 /var/lib/opengauss/data/pg_log
postgresql-2022-12-14_101515.log postgresql-2022-12-14_101526.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。
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=#
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。
omm=# SHOW max_connections;
max_connections
-----------------
200
(1 row)
omm=#
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),
omm(# 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
omm-# (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)
omm=#
--使用VACUUM或VACUUM FULL命令，进行磁盘空间回收。
--使用VACUUM
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。
omm=# VACUUM FULL customer_t;
VACUUM
omm=#
--使用ANALYZE语句更新统计信息。
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。
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。
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。
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=#
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。
omm=# REINDEX table HR.areaS;
REINDEX
omm=#
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 gausdb omm 544 523 0 10:32 pts/0 00:00:00 grep gausdb omm@modb:~$ ps -ef |grep gaussdb omm 1 0 0 10:14 ? 00:00:06 gaussdb omm 546 523 0 10:33 pts/0 00:00:00 grep gaussdb omm@modb:~$ ps -Tp 1 PID SPID TTY TIME CMD 1 1 ? 00:00:00 gaussdb 1 287 ? 00:00:00 jemalloc_bg_thd 1 293 ? 00:00:00 gaussdb 1 294 ? 00:00:00 syslogger 1 295 ? 00:00:00 jemalloc_bg_thd 1 296 ? 00:00:00 alarm 1 297 ? 00:00:00 reaper 1 298 ? 00:00:00 jemalloc_bg_thd 1 299 ? 00:00:00 jemalloc_bg_thd 1 343 ? 00:00:00 checkpointer 1 344 ? 00:00:00 Spbgwriter 1 345 ? 00:00:01 pagewriter 1 346 ? 00:00:00 pagewriter 1 348 ? 00:00:00 pagewriter 1 347 ? 00:00:00 pagewriter 1 349 ? 00:00:00 pagewriter 1 350 ? 00:00:00 WALwriter 1 351 ? 00:00:00 WALwriteraux 1 352 ? 00:00:00 AVClauncher 1 353 ? 00:00:00 Jobscheduler 1 354 ? 00:00:00 asyncundolaunch 1 355 ? 00:00:00 globalstats 1 356 ? 00:00:00 applylauncher 1 357 ? 00:00:00 statscollector 1 358 ? 00:00:00 percentworker 1 359 ? 00:00:02 ashworker 1 360 ? 00:00:00 TrackStmtWorker 1 361 ? 00:00:00 auditor 1 362 ? 00:00:00 2pccleaner 1 363 ? 00:00:00 faultmonitor 1 365 ? 00:00:00 WLMmonitor 1 366 ? 00:00:00 WLMarbiter 1 364 ? 00:00:00 WLMworker 1 367 ? 00:00:00 undorecycler omm@modb:~$ omm@modb:~$ gs_ctl status -D /var/lib/opengauss/data [2022-12-14 10:33:55.953][552][][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:~$ omm@modb:~$
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 | | | | | | | | | 11/322 | 281471432293616 | 28147143229
3616 | AccessShareLock | t | t | 4000:2eea:0:0:0:0 | 0:0#0
virtualxid | | | | | | 11/322 | | | | | 11/322 | 281471432293616 | 28147143229
3616 | ExclusiveLock | t | t | b:142:0:0:0:7 | 0:0#0
virtualxid | | | | | | 9/229 | | | | | 9/229 | 281471700729072 | 28147170072
9072 | ExclusiveLock | t | t | 9:e5:0:0:0:7 | 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 | wait_status | wait_event | locktag | lockmode | block_sessionid
| global_sessionid
-----------+---------+-------------+----------+-----+-----------+-------+------------+--------+-------+-------------+------------+---------+----------+-----------------
+------------------
(0 rows)
omm=#
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_101515.log postgresql-2022-12-14_101526.log
omm=# \q
omm@modb:~$
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_101515.log postgresql-2022-12-14_101526.log
omm@modb:/var/lib/opengauss/data/pg_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=#
omm=# SHOW max_connections;
max_connections
-----------------
200
(1 row)
omm=#
5、对表进行VACUUM、VACUUM FULL和ANALYZE操作
omm=# create table lxs1(id int);
CREATE TABLE
omm=# vacuum lxs1;
VACUUM
omm=# vacuum full lxs1;
VACUUM
omm=# vacuum analyze lxs1;
VACUUM
omm=#
6、建表、索引，进行重建索引操作
omm=# create table lxs2(id int);
CREATE TABLE
omm=# create index idx_lxs2_id on lxs2(id);
CREATE INDEX
omm=# reindex table lxs2;
NOTICE: table "lxs1" has no indexes
REINDEX
omm=#
omm=# reindex table lxs2;
REINDEX
omm=#
–学如逆水行舟，不进则退。
最后修改时间：2022-12-14 10:40:13
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