VACUUM

NAME
SYNOPSIS
DESCRIPTION æè¿°
PARAMETERS åæ°
OUTPUTS è¾åº
NOTES 注æ
EXAMPLES ä¾å
COMPATIBILITY å¼å®¹æ§
SEE ALSO åè§
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NAME

VACUUM - åå¾æ¶é以åå¯éå°åæä¸ä¸ªæ°æ®åº

SYNOPSIS

VACUUM [ FULL ] [ FREEZE ] [ VERBOSE ] [ table ]
VACUUM [ FULL ] [ FREEZE ] [ VERBOSE ] ANALYZE [ table [ (column [, ...] ) ] ]

DESCRIPTION æè¿°

VACUUM åæ¶å·²å é¤åç»å æ®çåå¨ç©ºé´ã å¨ä¸è¬ç PostgreSQL æä½éï¼ é£äºå·²ç» DELETE çåç»æè被 UPDATE è¿åè¿æ¶çåç»æ¯æ²¡æä»å®ä»¬æå±ç表ä¸ç©çå é¤çï¼ å¨å®æ VACUUM ä¹åå®ä»¬ä»ç¶åå¨ã å æ¤æ们æå¿é¡»å¨æå°è¿è¡ VACUUMï¼ ç¹å«æ¯å¨å¸¸æ´æ°ç表ä¸ã

å¦æ没æåæ°ï¼VACUUM å¤çå½åæ°æ®åºéæ¯ä¸ªè¡¨ï¼ å¦ææåæ°ï¼VACUUM åªå¤çé£ä¸ªè¡¨ã

VACUUM ANALYZE åæ§è¡ä¸ä¸ª VACUUM ç¶åæ¯ç»æ¯ä¸ªéå®ç表æ§è¡ä¸ä¸ª ANALYZEã 对äºæ¥å¸¸ç»´æ¤èæ¬èè¨ï¼è¿æ¯ä¸ä¸ªå¾æ¹ä¾¿çç»åãåé ANALYZE [analyze(7)] è·åæ´å¤æå³å¶å¤ççç»èã

ç®åç VACUUM ï¼æ²¡æFULLï¼ åªæ¯ç®åå°åæ¶ç©ºé´å¹¶ä¸ä»¤å¶å¯ä»¥å次使ç¨ãè¿ç§å½¢å¼çå½ä»¤å¯ä»¥å对表çæ®é读å并è¡æä½ï¼ å ä¸ºæ²¡æ请æ±æä»éãVACUUM FULL æ§è¡æ´å¹¿æ³çå¤çï¼åæ¬è·¨å移å¨åç»ï¼ä»¥ä¾¿æ表å缩å°æå°çç£çåæ°ç®éã è¿ç§å½¢å¼è¦æ¢è®¸å¤å¹¶ä¸å¨å¤ççæ¶åéè¦å¨è¡¨ä¸æ½å ä¸ä¸ªæå®éã

FREEZE æ¯ä¸ç§ç¹æ®ç¨éçé项ï¼å®å¯¼è´åç»å°½å¯è½å¿«å°æ è®°ä¸º"å»ç»(frozen)"ï¼ èä¸æ¯ç- å°å®ä»¬å·²ç»ç¸å½èçæ¶åææè®°ãå¦æå¨åä¸ä¸ªæ°æ®åºä¸æ²¡æå¶å®è¿è¡ççäºå¡çæ¶åå®æè¿ä¸ªå½ä»¤ï¼ é£ä¹ç³»ç»å°±ä¿è¯å¨æ°æ®åºéçææåç»é½æ¯"å»ç»(frozen)"çï¼ å æ¤ä¸ä¼æäºå¡ ID éå çé®é¢ï¼èåæ°æ®åºæªæ¸ççæ¶é´æ²¡æå³ç³»ã æ们ä¸å»ºè®®æ FREEZE ç¨åæ¥å¸¸ç¨éãæ们ç¨å®çå¯ä¸ç®å°æ¯åå¤åç¨æ·å®ä¹ç模æ¿æ°æ®åºèæ¥çæ¶åï¼ æèæ¯å¶å®å®å¨æ¯åªè¯»çï¼ ä¸ä¼çå°æ¥å¸¸ç»´æ¤æ§ VACUUM æä½çæ°æ®åºã åé Chapter 21 ‘‘Routine Database Maintenance’’ è·åç»èã

PARAMETERS åæ°

FULL

éæ©"å®å¨"æ¸çï¼è¿æ ·å¯ä»¥æ¢å¤æ´å¤ç空é´ï¼ ä½æ¯è±çæ¶é´æ´å¤å¹¶ä¸å¨è¡¨ä¸æ½å äºæå®éã

FREEZE

éæ©æ¿è¿çåç»"å»ç»"ã

VERBOSE

为æ¯ä¸ªè¡¨æå°ä¸ä»½è¯¦ç»çæ¸çå·¥ä½æ¥åã

ANALYZE

æ´æ°ç¨äºä¼åå¨çç»è®¡ä¿¡æ¯ï¼ä»¥å³å®æ§è¡æ¥è¯¢çææææ¹æ³ã

table

è¦æ¸çç表çå称ï¼å¯ä»¥æ模å¼ä¿®é¥°ï¼ã缺çæ¶æ¯å½åæ°æ®åºä¸çææ表ã

column

è¦åæçå·ä½çå/å段å称ã缺çæ¯ææå/å段ã

OUTPUTS è¾åº

å¦æ声æäº VERBOSEï¼VACUUM ååºè¿ç¨ä¿¡æ¯ï¼ 以表æå½åæ- £å¨å¤çé£ä¸ªè¡¨ãåç§æå³è¿äºè¡¨çç»è®¡ä¹ä¼æå°åºæ¥ã

NOTES 注æ

æ们建议å¨ç»å¸¸VACUUMMï¼æ¸çï¼ï¼è³å°æ¯æä¸æ¬¡ï¼ç产æ°æ®åºï¼ 以ä¿è¯ä¸æå°å é¤å¤±æçè¡ãå°¤å¶æ¯å¨å¢å äºå¤§éè®°å½ä¹åï¼ å¯¹åå½±åç表æ§è¡ VACUUM ANALYZE å½ä»¤æ¯ä¸ä¸ªå¾å¥½çä¹ æ¯ãè¿æ ·åå°æ´æ°ç³»ç»ç®å½ä¸ºæè¿çæ´æ¹ï¼å¹¶ä¸å许 PostgreSQL æ¥è¯¢ä¼åå¨å¨è§åç¨æ·æ¥è¯¢æ¶ææ´å¥½çéæ©ã

æ们ä¸å»ºè®®æ¥å¸¸ä½¿ç¨ FULL é项ï¼ä½æ¯å¯ä»¥å¨ç¹æ®æåµä¸ä½¿ç¨ã ä¸ä¸ªä¾å- å°±æ¯å¨ä½åé¤äºä¸ä¸ªè¡¨ç大é¨åè¡ä¹åï¼å¸æä»ç©çä¸ç¼©å°è¯¥è¡¨ä»¥åå°ç£ç空é´åç¨ãVACUUM FULL é常è¦æ¯å纯ç VACUUM æ¶ç¼©æ´å¤è¡¨ç尺寸ã

EXAMPLES ä¾å

ä¸é¢æ¯ä¸ä¸ªå¨ regression ï¼èåï¼æ°æ®åºéæ个表ä¸æ§è¡ VACUUMçä¸ä¸ªä¾åï¼

regression=# VACUUM VERBOSE ANALYZE onek;
INFO: vacuuming "public.onek"
INFO: index "onek_unique1" now contains 1000 tuples in 14 pages
DETAIL: 3000 index tuples were removed.
0 index pages have been deleted, 0 are currently reusable.
CPU 0.01s/0.08u sec elapsed 0.18 sec.
INFO: index "onek_unique2" now contains 1000 tuples in 16 pages
DETAIL: 3000 index tuples were removed.
0 index pages have been deleted, 0 are currently reusable.
CPU 0.00s/0.07u sec elapsed 0.23 sec.
INFO: index "onek_hundred" now contains 1000 tuples in 13 pages
DETAIL: 3000 index tuples were removed.
0 index pages have been deleted, 0 are currently reusable.
CPU 0.01s/0.08u sec elapsed 0.17 sec.
INFO: index "onek_stringu1" now contains 1000 tuples in 48 pages
DETAIL: 3000 index tuples were removed.
0 index pages have been deleted, 0 are currently reusable.
CPU 0.01s/0.09u sec elapsed 0.59 sec.
INFO: "onek": removed 3000 tuples in 108 pages
DETAIL: CPU 0.01s/0.06u sec elapsed 0.07 sec.
INFO: "onek": found 3000 removable, 1000 nonremovable tuples in 143 pages
DETAIL: 0 dead tuples cannot be removed yet.
There were 0 unused item pointers.
0 pages are entirely empty.
CPU 0.07s/0.39u sec elapsed 1.56 sec.
INFO: analyzing "public.onek"
INFO: "onek": 36 pages, 1000 rows sampled, 1000 estimated total rows
VACUUM

COMPATIBILITY å¼å®¹æ§

SQL æ åé没æ VACUUM è¯å¥ã

SEE ALSO åè§

vacuumdb [vacuumdb(1)]

è¯è

Postgresql ä¸æç½ç« ä½ä¼å¹³ <laser@pgsqldb.org>

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æ¬é¡µé¢ä¸æçç±ä¸æ man æå页计åæä¾ã
ä¸æ man æå页计åï¼https://github.com/man-pages-zh/manpages-zh

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