Re: Meaning of vacuum output
От | Jeffrey W. Baker |
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Тема | Re: Meaning of vacuum output |
Дата | |
Msg-id | 1011205133.16847.24.camel@heat обсуждение исходный текст |
Ответ на | Re: Meaning of vacuum output (Tom Lane <tgl@sss.pgh.pa.us>) |
Ответы |
Re: Meaning of vacuum output
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Список | pgsql-general |
On Wed, 2002-01-16 at 10:08, Tom Lane wrote: > "Jeffrey W. Baker" <jwbaker@acm.org> writes: > > rupert=# vacuum verbose resp_header; > > NOTICE: --Relation resp_header-- > > NOTICE: Pages 28276: Changed 4, Empty 0; Tup 2437108: Vac 0, Keep > > 2295773, UnUsed 96275. > > Total CPU 1.79s/0.38u sec elapsed 2.72 sec. > > VACUUM > > rupert=# select count(*) from resp_header; > > count > > -------- > > 141357 > > (1 row) > > > There's nowhere near 2.437e6 tuples in the table, but the difference > > between Tup and Keep seems to be the number of tuples in the table. But > > what does this mean? Are there 2.295e6 deleted tuples hanging around in > > the table? > > Kinda looks that way. Do you have open transactions hanging around that > might still be able to see those tuples? I shut down all connections, and vacuum has a different output: NOTICE: Pages 33639: Changed 226, Empty 0; Tup 128819: Vac 2840812, Keep 0, UnUsed 96275. Total CPU 14.29s/28.69u sec elapsed 233.02 sec. So I conclude from these two data points that Keep means tuples that are still visible to a transaction, Vac means tuples that are not visible to any transaction. But, what is UnUsed? -jwb
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