Re: Failing start-up archive recovery at Standby mode in PG9.2.4
От | Heikki Linnakangas |
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Тема | Re: Failing start-up archive recovery at Standby mode in PG9.2.4 |
Дата | |
Msg-id | 517A2838.5090105@vmware.com обсуждение исходный текст |
Ответ на | Re: Failing start-up archive recovery at Standby mode in PG9.2.4 (Kyotaro HORIGUCHI <kyota.horiguchi@gmail.com>) |
Список | pgsql-hackers |
On 26.04.2013 07:02, Kyotaro HORIGUCHI wrote: > I am uncertain a bit weather it is necessary to move curFileTLI to > anywhere randomly read . On a short glance, the random access occurs also > for reading checkpoint-related records. I didn't understand that. > Also I don't have clear distinction between lastSegmentTLI and curFileTLI > after the patch applied. In short, lastSegmentTLI is the TLI in first page of the last opened segment, while curFileTLI is the TLI in the filename of the last opened segment. Usually they're the same, but in a segment that contains a timeline switch, they differ. For example, if you perform PITR to a point in the middle of segment 000000010000000000000062, you end up with two segments: 000000010000000000000062 000000020000000000000062 The first half of those files are identical, but the latter contains a time-line changing checkpoint record in the middle, and from that point on the contents are different. When we open file 000000020000000000000062, lastSegmentTLI is 1, because the first half of that segment contains WAL from timeline 1, but curFileTLI is 2, because that's the TLI in the filename. - Heikki
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