mirror of
https://git.postgresql.org/git/postgresql.git
synced 2024-08-28 00:07:20 +02:00
c780a7a90a
CheckBuffer() is designed to be a concurrent-safe function able to run sanity checks on a relation page without loading it into the shared buffers. The operation is done using a lock on the partition involved in the shared buffer mapping hashtable and an I/O lock for the buffer itself, preventing the risk of false positives due to any concurrent activity. The primary use of this function is the detection of on-disk corruptions for relation pages. If a page is found in shared buffers, the on-disk page is checked if not dirty (a follow-up checkpoint would flush a valid version of the page if dirty anyway), as it could be possible that a page was present for a long time in shared buffers with its on-disk version corrupted. Such a scenario could lead to a corrupted cluster if a host is plugged off for example. If the page is not found in shared buffers, its on-disk state is checked. PageIsVerifiedExtended() is used to apply the same sanity checks as when a page gets loaded into shared buffers. This function will be used by an upcoming patch able to check the state of on-disk relation pages using a SQL function. Author: Julien Rouhaud, Michael Paquier Reviewed-by: Masahiko Sawada Discussion: https://postgr.es/m/CAOBaU_aVvMjQn=ge5qPiJOPMmOj5=ii3st5Q0Y+WuLML5sR17w@mail.gmail.com |
||
|---|---|---|
| .. | ||
| buffer | ||
| file | ||
| freespace | ||
| ipc | ||
| large_object | ||
| lmgr | ||
| page | ||
| smgr | ||
| sync | ||
| Makefile | ||