database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-06-16 06:01:02 +03:00
Code Activity

Add GUC to enable WAL-logging of hint bits, even with checksums disabled.

Browse Source 
WAL records of hint bit updates is useful to tools that want to examine
which pages have been modified. In particular, this is required to make
the pg_rewind tool safe (without checksums).

This can also be used to test how much extra WAL-logging would occur if
you enabled checksums, without actually enabling them (which you can't
currently do without re-initdb'ing).

Sawada Masahiko, docs by Samrat Revagade. Reviewed by Dilip Kumar, with
further changes by me.
This commit is contained in:
Heikki Linnakangas
2013-12-13 16:26:14 +02:00
parent 56afe8509e
commit 50e547096c
13 changed files with 70 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

7
src/backend/storage/buffer/bufmgr.c
View File

@ -2626,16 +2626,15 @@ MarkBufferDirtyHint(Buffer buffer, bool buffer_std)
bool delayChkpt = false;
/*
* If checksums are enabled, and the buffer is permanent, then a full
* page image may be required even for some hint bit updates to
* protect against torn pages. This full page image is only necessary
* If we need to protect hint bit updates from torn writes, WAL-log a
* full page image of the page. This full page image is only necessary
* if the hint bit update is the first change to the page since the
* last checkpoint.
*
* We don't check full_page_writes here because that logic is included
* when we call XLogInsert() since the value changes dynamically.
*/
if (DataChecksumsEnabled() && (bufHdr->flags & BM_PERMANENT))
if (XLogHintBitIsNeeded() && (bufHdr->flags & BM_PERMANENT))
{
/*
* If we're in recovery we cannot dirty a page because of a hint.