For example, if page lsn in storage is 0x90000 and start to replay from 0x10000. If 0x10000 is full-page xlog record, then we can ignore to replay xlog between 0x10000~0x90000 for this page.
Is there any correct issue if the page exists in the buffer pool and ignore to replay for full-page or init page if page lsn is larger than the lsn of xlog record? At 2020-03-13 23:41:03, "Alvaro Herrera" <alvhe...@2ndquadrant.com> wrote: >On 2020-Mar-13, Thunder wrote: > >> Hello hackers： >> >> >> During crash recovery, we compare most of the lsn of xlog record with page >> lsn to determine if the record has already been replayed. >> The exceptions are full-page and init-page xlog records. >> It's restored if the xlog record includes a full-page image of the page. >> And it initializes the page if the xlog record include init page information. >> >> >> When we enable checksum for the page and verify page success, can we >> compare the page lsn with the lsn of full-page xlog record or init >> page xlog record to detemine it has already been replayed? > >In order to verify that the checksum passes, you have to read the page >first. So what are you optimizing? > >-- >Álvaro Herrera https://www.2ndQuadrant.com/ >PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
