On 30.05.2013 11:26, Heikki Linnakangas wrote:
On 30.05.2013 06:54, Jeff Davis wrote:
Continuation of:
http://www.postgresql.org/message-id/1353551097.11440.128.camel@sussancws0025
Rebased patch attached; no other changes.
@@ -675,6 +675,16 @@ lazy_scan_heap(Relation onerel, LVRelStats
*vacrelstats,
}
/*
+ * If this page is left over from an upgraded system, it may have a
+ * PD_ALL_VISIBLE bit set (which is deprecated). If so, clear it.
+ */
+ if (PageIsAllVisible(page))
+ {
+ PageClearAllVisible(page);
+ MarkBufferDirty(buf);
+ }
+
+ /*
* Prune all HOT-update chains in this page.
*
* We count tuples removed by the pruning step as removed by VACUUM.
That could cause a torn page and checksum failure if checksums are
enabled.
Come to think of it, even without the torn page & checksum issue, do we
really want to actively clear the all-visible flags after upgrade? For
tables that haven't been changed, and thus have the all-visible bits
set, that amounts to a complete rewrite on the first vacuum after
upgrade. That's expensive.
- Heikki
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