本节简单介绍了可用于诊断PostgreSQL数据库参数设置的工具：postgresqltuner,包括该工具的安装和基本使用。
一、安装
在REHL系列下安装：
#该工具基于Perl语言开发,首先安装Perl相关的开发包
#yum -y install perl-DBD-Pg
#获取工具包
#cd /tmp
#wget -O postgresqltuner.pl https://postgresqltuner.pl
#chmod +x postgresqltuner.pl
二、基本使用
在数据库主机上执行:
[xdb@localhost bin]$ /tmp/postgresqltuner.pl --host=localhost --user xdb --database testdb
postgresqltuner.pl version 1.0.0
Connecting to localhost:5432 database testdb with user xdb...
Argument "11beta2" isn't numeric in numeric gt (>) at /tmp/postgresqltuner.pl line 818.
[OK] User used for report have super rights
===== OS information =====
[INFO] OS: linux Version: 3.10.0-514.16.1.el7.x86_64 Arch: x86_64-linux-thread-multi
[INFO] OS total memory: 732.52 MB
[BAD] Memory overcommitment is allowed on the system. This can lead to OOM Killer killing some PostgreSQL process, which will cause a PostgreSQL server restart (crash recovery)
[INFO] sysctl vm.overcommit_ratio=50
[BAD] vm.overcommit_ratio is too small, you will not be able to use more than 50*RAM+SWAP for applications
[INFO] Currently used I/O scheduler(s) : deadline
===== General instance informations =====
----- Version -----
Argument "11beta2" isn't numeric in numeric gt (>) at /tmp/postgresqltuner.pl line 818.
[OK] You are using last 11beta2
----- Uptime -----
[INFO] Service uptime : 09m 53s
[WARN] Uptime is less than 1 day. postgresqltuner.pl result may not be accurate
----- Databases -----
[INFO] Database count (except templates): 2
[INFO] Database list (except templates): postgres testdb
----- Extensions -----
[INFO] Number of activated extensions : 1
[INFO] Activated extensions : plpgsql
[WARN] Extensions pg_stat_statements is disabled
----- Users -----
[OK] No user account will expire in less than 7 days
[OK] No user with password=username
[OK] Password encryption is enabled
----- Connection information -----
[INFO] max_connections: 100
[INFO] current used connections: 6 (6.00%)
[INFO] 3 are reserved for super user (3.00%)
[INFO] Average connection age : 08m 14s
[WARN] Average connection age is less than 10 minutes. Use a connection pooler to limit new connection/seconds
----- Memory usage -----
[INFO] configured work_mem: 4.00 MB
[INFO] Using an average ratio of work_mem buffers by connection of 150% (use --wmp to change it)
[INFO] total work_mem (per connection): 6.00 MB
[INFO] shared_buffers: 128.00 MB
Argument "11beta2" isn't numeric in numeric gt (>) at /tmp/postgresqltuner.pl line 818.
[INFO] Track activity reserved size : 0.00 B
[WARN] maintenance_work_mem is less or equal default value. Increase it to reduce maintenance tasks time
[INFO] Max memory usage :
shared_buffers (128.00 MB)
+ max_connections * work_mem * average_work_mem_buffers_per_connection (100 * 4.00 MB * 150 / 100 = 600.00 MB)
+ autovacuum_max_workers * maintenance_work_mem (3 * 64.00 MB = 192.00 MB)
+ track activity size (0.00 B)
= 920.00 MB
[INFO] effective_cache_size: 4.00 GB
[INFO] Size of all databases : 33.19 MB
[WARN] shared_buffer is too big for the total databases size, memory is lost
[INFO] PostgreSQL maximum memory usage: 125.59% of system RAM
[BAD] Max possible memory usage for PostgreSQL is more than system total RAM. Add more RAM or reduce PostgreSQL memory
[INFO] max memory+effective_cache_size is 684.76% of total RAM
[WARN] the sum of max_memory and effective_cache_size is too high, the planer can find bad plans if system cache is smaller than expected
----- Logs -----
[OK] log_hostname is off : no reverse DNS lookup latency
[WARN] log of long queries is desactivated. It will be more difficult to optimize query performances
[OK] log_statement=none
----- Two phase commit -----
Argument "11beta2" isn't numeric in numeric gt (>) at /tmp/postgresqltuner.pl line 818.
[OK] Currently no two phase commit transactions
----- Autovacuum -----
[OK] autovacuum is activated.
[INFO] autovacuum_max_workers: 3
----- Checkpoint -----
[WARN] checkpoint_completion_target(0.5) is low
----- Disk access -----
[OK] fsync is on
[OK] synchronize_seqscans is on
----- WAL -----
Argument "11beta2" isn't numeric in numeric gt (>) at /tmp/postgresqltuner.pl line 818.
----- Planner -----
[OK] costs settings are defaults
[BAD] some plan features are disabled : enable_partitionwise_aggregate,enable_partitionwise_join
===== Database information for database testdb =====
----- Database size -----
[INFO] Database testdb total size : 11.44 MB
Argument "11beta2" isn't numeric in numeric gt (>) at /tmp/postgresqltuner.pl line 818.
[INFO] Database testdb tables size : 8.38 MB (73.22%)
[INFO] Database testdb indexes size : 3.06 MB (26.78%)
----- Tablespace location -----
Argument "11beta2" isn't numeric in numeric gt (>) at /tmp/postgresqltuner.pl line 818.
[OK] No tablespace in PGDATA
----- Shared buffer hit rate -----
[INFO] shared_buffer_heap_hit_rate: 99.03%
[INFO] shared_buffer_toast_hit_rate: 0.00%
[INFO] shared_buffer_tidx_hit_rate: 28.57%
[INFO] shared_buffer_idx_hit_rate: 98.43%
[OK] Shared buffer idx hit rate is very good
----- Indexes -----
[OK] No invalid indexes
Argument "11beta2" isn't numeric in numeric gt (>) at /tmp/postgresqltuner.pl line 818.
[OK] No unused indexes
----- Procedures -----
[OK] No procedures with default costs
===== Configuration advices =====
----- checkpoint -----
[MEDIUM] Your checkpoint completion target is too low. Put something nearest from 0.8/0.9 to balance your writes better during the checkpoint interval
----- extension -----
[LOW] Enable pg_stat_statements to collect statistics on all queries (not only queries longer than log_min_duration_statement in logs)
----- sysctl -----
[URGENT] set vm.overcommit_memory=2 in /etc/sysctl.conf and run sysctl -p to reload it. This will disable memory overcommitment and avoid postgresql killed by OOM killer.
执行完毕,该工具会输出一系列的参数调整建议.这些参数的含义和为何如此调整,下节讨论.
三、小结
本节简单介绍了postgresqltuner.pl工具的安装和基本使用,有兴趣的可以查看该工具postgresqltuner的源码并进行改进.