Fix WAL-logging of FSM and VM truncation.
When a relation is truncated, it is important that the FSM is truncated as
well. Otherwise, after recovery, the FSM can return a page that has been
truncated away, leading to errors like:
ERROR: could not read block 28991 in file "base/16390/572026": read only 0
of 8192 bytes
We were using MarkBufferDirtyHint() to dirty the buffer holding the last
remaining page of the FSM, but during recovery, that might in fact not
dirty the page, and the FSM update might be lost.
To fix, use the stronger MarkBufferDirty() function. MarkBufferDirty()
requires us to do WAL-logging ourselves, to protect from a torn page, if
checksumming is enabled.
Also fix an oversight in visibilitymap_truncate: it also needs to WAL-log
when checksumming is enabled.
Analysis by Pavan Deolasee.
Discussion: <CABOikdNr5vKucqyZH9s1Mh0XebLs_jRhKv6eJfNnD2wxTn=_9A@mail.gmail.com>
Backpatch to 9.3, where we got data checksums.
Branch
------
REL9_6_STABLE
Details
-------
http://git.postgresql.org/pg/commitdiff/142530ef0e683af4f063e4efd3b322cd3e9ea87e
Modified Files
--------------
src/backend/access/heap/visibilitymap.c | 16 ++++++
src/backend/storage/freespace/freespace.c | 20 ++++++-
src/test/recovery/t/008_fsm_truncation.pl | 93 +++++++++++++++++++++++++++++++
3 files changed, 128 insertions(+), 1 deletion(-)