잠시만 기다려 주세요

HOME   |  여기는?   |  바다물때표   |  여러가지 팁 (833)  |  추천 및 재미 (97)  |  자료실 (18)  |  끄적거림 (475)  |  시나리오 (760)  |  드라마 대본 (248)  |  

2020년 02월 19일
고통은 언제나 오고가는 손님과 같다. - 바다아이
 




    DATABASE

DATABASE - Optimize and Improve PostgreSQL Performance with VACUUM, ANALYZE, and REINDEX
이 름 : 바다아이   |   조회수 : 2312         짧은 주소 : https://www.bada-ie.com/su/?481531577295

Purpose

If you have your application running on a PostgreSQL database, there are some commands that can be run to improve and optimize performance. Three of these will be introduced in this article: VACUUM, ANALYZE, and REINDEX.

To avoid conflicting database updates, or corrupted data, it is preferable to run these commands during a maintenance window when the application is stopped.
 

In the default PostgreSQL configuration, the AUTOVACUUM daemon is enabled and all required configuration parameters are set as needed. The daemon will run VACUUM and ANALYZE at regular intervals. If you have the damon enabled, these commands can be run to supplement the daemon's work. To confirm whether the autovacuum daemon is running on UNIX, you can check the processlist

$ ps aux|grep autovacuum|grep -v grep
postgres           334   0.0  0.0  2654128   1232   ??  Ss   16Mar17   0:05.63 postgres: autovacuum launcher process  

On UNIX or Windows, you can find the status of autovacuum in the pg_settings database with the query below:

select name, setting from pg_settings where name = 'autovacuum' ;

VACUUM

The VACUUM command will reclaim space still used by data that had been updated. In PostgreSQL, updated key-value tuples are not removed from the tables when rows are changed, so the VACUUM command should be run occasionally to do this.

VACUUM can be run on its own, or with ANALYZE.

When the option list is surrounded by parentheses, the options can be written in any order. Without parentheses, options must be specified in exactly the order shown below. The parenthesized syntax was added in PostgreSQL 9.0; after which the unparenthesized syntax is deprecated.

Examples

In the examples below, [tablename] is optional. Without a table specified, VACUUM will be run on available tables in the current schema that the user has access to.

  1. Plain VACUUM: Frees up space for re-use

    VACUUM [tablename]
  2. Full VACUUM: Locks the database table, and reclaims more space than a plain VACUUM

    /* Before Postgres 9.0: */
    VACUUM FULL
    /* Postgres 9.0+: */
    VACUUM(FULL) [tablename]
  3. Full VACUUM and ANALYZE: Performs a Full VACUUM and gathers new statistics on query executions paths using ANALYZE

    /* Before Postgres 9.0: */
    VACUUM FULL ANALYZE [tablename]
    /* Postgres 9.0+: */
    VACUUM(FULL, ANALYZE) [tablename]
  4. Verbose Full VACUUM and ANALYZE: Same as #3, but with verbose progress output

    /* Before Postgres 9.0: */
    VACUUM FULL VERBOSE ANALYZE [tablename]
    /* Postgres 9.0+: */
    VACUUM(FULL, ANALYZE, VERBOSE) [tablename]

 

ANALYZE

ANALYZE gathers statistics for the query planner to create the most efficient query execution paths. Per PostgreSQL documentation, accurate statistics will help the planner to choose the most appropriate query plan, and thereby improve the speed of query processing. 

Example

In the example below, [tablename] is optional. Without a table specified, ANALYZE will be run on available tables in the current schema that the user has access to.

ANALYZE VERBOSE [tablename]

 

REINDEX

The REINDEX command rebuilds one or more indices, replacing the previous version of the index. REINDEX can be used in many scenarios, including the following (from Postgres documentation):

  • An index has become corrupted, and no longer contains valid data. Although in theory this should never happen, in practice indexes can become corrupted due to software bugs or hardware failures. REINDEX provides a recovery method.
  • An index has become "bloated", that is it contains many empty or nearly-empty pages. This can occur with B-tree indexes in PostgreSQL under certain uncommon access patterns. REINDEX provides a way to reduce the space consumption of the index by writing a new version of the index without the dead pages.

  • You have altered a storage parameter (such as fillfactor) for an index, and wish to ensure that the change has taken full effect.

  • An index build with the CONCURRENTLY option failed, leaving an "invalid" index. Such indexes are useless but it can be convenient to use REINDEX to rebuild them. Note that REINDEX will not perform a concurrent build. To build the index without interfering with production you should drop the index and reissue the CREATE INDEX CONCURRENTLY command.

Examples

Any of these can be forced by adding the keyword FORCE after the command

  1. Recreate a single index, myindex:

    REINDEX INDEX myindex
  2. Recreate all indices in a table, mytable:

    REINDEX TABLE mytable
  3. Recreate all indices in schema public:

    REINDEX SCHEMA public
  4. Recreate all indices in database postgres:

    REINDEX DATABASE postgres
  5. Recreate all indices on system catalogs in database postgres:

    REINDEX SYSTEM postgres
    
    
    
    출처 : https://confluence.atlassian.com/kb/optimize-and-improve-postgresql-performance-with-vacuum-analyze-and-reindex-885239781.html
    
| |


      1 page / 3 page
번 호 카테고리 제 목 이름 조회수
73 DATABASE postgresql log_timezone .... 바다아이 119
72 DATABASE db .. dbeaver, db admin tool 바다아이 1579
71 DATABASE postgresql SEQUENCE reset .... 바다아이 1283
70 DATABASE mysql, mariadb , , , , left, substring, right, concat 바다아이 1702
69 DATABASE [PostgreSql] WITH , , Operator 바다아이 1327
68 DATABASE postgresql for, foreach , 바다아이 1421
67 DATABASE postgresql , , into ... 바다아이 1312
66 DATABASE postgresql PL/pgSQL - SQL Procedural Language, , 바다아이 3560
65 DATABASE postgresql ... .. 바다아이 1711
64 DATABASE postgresql CSV export/import 바다아이 1624
63 DATABASE postgresql tablespace , .... 바다아이 2070
62 DATABASE postgresql 10 partitioning, ... , ... 바다아이 1748
61 DATABASE Using PostgreSQL Arrays, ... ... 바다아이 1722
60 DATABASE PostgreSQL (TRIGGER) (function) 바다아이 1611
59 DATABASE mysql, mariadb DISTINCT GROUP BY 바다아이 1494
현재글 DATABASE Optimize and Improve PostgreSQL Performance with VACUUM, ANALYZE, and REINDEX 바다아이 2313
57 DATABASE postgresql tuple . vacuumdb .. , . 바다아이 1655
56 DATABASE RDBMS SQL MONGODB ... 바다아이 1435
55 DATABASE mysql 5.x my.cnf 바다아이 1690
54 DATABASE postgresql , .. 바다아이 1800
53 DATABASE postgresql , size, 바다아이 2549
52 DATABASE postgresql , , .... 바다아이 1558
51 DATABASE PostgreSQL Replication, , , master, slave 바다아이 2044
50 DATABASE postgresql case 바다아이 1675
49 DATABASE postgresql with 바다아이 1659
48 DATABASE postgresql , , string 바다아이 1885
47 DATABASE / SELECT , 바다아이 1763
46 DATABASE Postgresql partitioning table , , , 바다아이 1975
45 DATABASE PostgreSQL 바다아이 1991
44 DATABASE postgresql vacuumdb, psql, pg_dump password crontab 바다아이 2218
| |






Copyright ⓒ 2001.12. bada-ie.com. All rights reserved.
이 사이트는 리눅스에서 firefox 기준으로 작성되었습니다. 기타 브라우저에서는 다르게 보일 수 있습니다.
[ FreeBSD + GoLang + PostgreSQL ]
서버위치 : 서울 Amazon Lightsail  실행시간 : 0.21013
to webmaster... gogo sea. gogo sea.