Re: Checkpoint cost, looks like it is WAL/CRC

Поиск
Список
Период
Сортировка
От Zeugswetter Andreas DAZ SD
Тема Re: Checkpoint cost, looks like it is WAL/CRC
Дата
Msg-id E1539E0ED7043848906A8FF995BDA57945BA2D@m0143.s-mxs.net
обсуждение исходный текст
Ответ на Checkpoint cost, looks like it is WAL/CRC  (Josh Berkus <josh@agliodbs.com>)
Ответы Re: Checkpoint cost, looks like it is WAL/CRC  (Tom Lane <tgl@sss.pgh.pa.us>)
Список pgsql-hackers
> Here's an idea:
>
> We read the page that we would have backed up, calc the CRC and
> write a short WAL record with just the CRC, not the block. When
> we recover we re-read the database page, calc its CRC and
> compare it with the CRC from the transaction log. If they
> differ, we know that the page was torn and we know the database
> needs recovery. (So we calc the CRC when we log AND when we recover).

Won't work, since the page on disk may have x different contents
between 2 checkpoints (bgwriter from lru).

Only workable solution would imho be to write the LSN to each 512
byte block (not that I am propagating that idea).

Andreas


В списке pgsql-hackers по дате отправления:

Предыдущее
От: "Zeugswetter Andreas DAZ SD"
Дата:
Сообщение: Re: Checkpoint cost, looks like it is WAL/CRC
Следующее
От: Tom Lane
Дата:
Сообщение: Re: Checkpoint cost, looks like it is WAL/CRC