本篇內(nèi)容主要講解“PostgreSQL 12在日志記錄上的改進是什么”，感興趣的朋友不妨來看看。本文介紹的方法操作簡單快捷，實用性強。下面就讓小編來帶大家學(xué)習(xí)“PostgreSQL 12在日志記錄上的改進是什么”吧!
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對于每一個客戶端連接，PG都會請求Postmaster，然后fork一個后臺進程來處理請求，Postmaster期望每一個客戶端請求發(fā)送startup message給PG Server，startup packet中的信息用于配置fork的后臺進程。對于端口掃描、HA解決方案中的心跳檢測等等都會發(fā)請求給PG Server port，PG會啟動進程來處理這些連接，但安全檢測、HA腳本等不同于常規(guī)的客戶端，對于這些請求，PG會產(chǎn)生一條日志條目，因此會造成日志文件的膨脹而導(dǎo)致不必要的IO開銷。
PG 11
使用工具nc來訪問數(shù)據(jù)庫端口，日志中會產(chǎn)生無用的日志條目。
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[xdb@localhost ~]$ psql -c 'select version();'
Timing is on.
Expanded display is used automatically.
version
---------------------------------------------------------------------------------------------------------
PostgreSQL 11.2 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-16), 64-bit
(1 row)
Time: 56.253 ms
[xdb@localhost ~]$
[xdb@localhost ~]$ for i in {1..100}; do nc -zv localhost 5110 ; done
Ncat: 0 bytes sent, 0 bytes received in 0.01 seconds.
Ncat: Version 7.50 ( https://nmap.org/ncat )
Ncat: Connected to ::1:5110.
Ncat: 0 bytes sent, 0 bytes received in 0.01 seconds.
Ncat: Version 7.50 ( https://nmap.org/ncat )
Ncat: Connected to ::1:5110.
Ncat: 0 bytes sent, 0 bytes received in 0.01 seconds.
Ncat: Version 7.50 ( https://nmap.org/ncat )
Ncat: Connected to ::1:5110.
Ncat: 0 bytes sent, 0 bytes received in 0.01 seconds.
Ncat: Version 7.50 ( https://nmap.org/ncat )
Ncat: Connected to ::1:5110.
Ncat: 0 bytes sent, 0 bytes received in 0.01 seconds.
...數(shù)據(jù)庫日志輸出
2019-12-09 14:35:55.468 CST,,,16065,"::1:57554",5dedeb4b.3ec1,1,"",2019-12-09 14:35:55 CST,,0,LOG,08P01,"incomplete startup packet",,,,,,,,,"" 2019-12-09 14:35:55.479 CST,,,16067,"::1:57556",5dedeb4b.3ec3,1,"",2019-12-09 14:35:55 CST,,0,LOG,08P01,"incomplete startup packet",,,,,,,,,"" 2019-12-09 14:35:55.490 CST,,,16069,"::1:57558",5dedeb4b.3ec5,1,"",2019-12-09 14:35:55 CST,,0,LOG,08P01,"incomplete startup packet",,,,,,,,,"" 2019-12-09 14:35:55.503 CST,,,16071,"::1:57560",5dedeb4b.3ec7,1,"",2019-12-09 14:35:55 CST,,0,LOG,08P01,"incomplete startup packet",,,,,,,,,"" 2019-12-09 14:35:55.513 CST,,,16073,"::1:57562",5dedeb4b.3ec9,1,"",2019-12-09 14:35:55 CST,,0,LOG,08P01,"incomplete startup packet",,,,,,,,,"" ...
這些日志其實是無用的日志信息，可以不作記錄。
PG 12
[xdb@localhost ~]$ psql -h localhost -p 5120 -U pg12 -c 'select version();'
Timing is on.
Expanded display is used automatically.
version
---------------------------------------------------------------------------------------------------------
PostgreSQL 12.1 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-16), 64-bit
(1 row)
Time: 60.207 ms
[xdb@localhost ~]$
[xdb@localhost ~]$ for i in {1..100}; do nc -zv localhost 5120 ; done
Ncat: 0 bytes sent, 0 bytes received in 0.01 seconds.
Ncat: Version 7.50 ( https://nmap.org/ncat )
Ncat: Connected to ::1:5120.
Ncat: 0 bytes sent, 0 bytes received in 0.01 seconds.
Ncat: Version 7.50 ( https://nmap.org/ncat )
Ncat: Connected to ::1:5120.
Ncat: 0 bytes sent, 0 bytes received in 0.01 seconds.
Ncat: Version 7.50 ( https://nmap.org/ncat )
Ncat: Connected to ::1:5120.
Ncat: 0 bytes sent, 0 bytes received in 0.01 seconds.
Ncat: Version 7.50 ( https://nmap.org/ncat )
Ncat: Connected to ::1:5120.
Ncat: 0 bytes sent, 0 bytes received in 0.01 seconds.
Ncat: Version 7.50 ( https://nmap.org/ncat )
Ncat: Connected to ::1:5120.
Ncat: 0 bytes sent, 0 bytes received in 0.01 seconds.
[xdb@localhost ~]$
...數(shù)據(jù)庫日志信息，相對于PG 11，沒有出現(xiàn)無用的日志信息
[pg12@localhost ~]$ tail -f $PGDATA/pg_log/postgresql-2019-12-09.log 2019-12-09 14:18:59.317 CST [1813] LOG: ending log output to stderr 2019-12-09 14:18:59.317 CST [1813] HINT: Future log output will go to log destination "csvlog".
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