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Fix handling of all-zero pages in SP-GiST vacuum.

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SP-GiST initialized an all-zeros page at vacuum, but that was not
WAL-logged, which is not safe. You might get a torn page write, when it gets
flushed to disk, and end-up with a half-initialized index page. To fix,
leave it in the all-zeros state, and add it to the FSM. It will be
initialized when reused. Also don't set the page-deleted flag when recycling
an empty page. That was also not WAL-logged, and a torn write of that would
cause the page to have an invalid checksum.

Backpatch to 9.2, where SP-GiST indexes were added.
This commit is contained in:
Heikki Linnakangas
2015-07-27 12:28:21 +03:00
parent 65c384c5ab
commit 023430abf7
2 changed files with 10 additions and 21 deletions
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4
src/include/access/spgist_private.h
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@@ -48,14 +48,14 @@ typedef SpGistPageOpaqueData *SpGistPageOpaque;
/* Flag bits in page special space */
#define SPGIST_META (1<<0)
#define SPGIST_DELETED (1<<1)
#define SPGIST_DELETED (1<<1) /* never set, but keep for backwards
* compatibility */
#define SPGIST_LEAF (1<<2)
#define SPGIST_NULLS (1<<3)
#define SpGistPageGetOpaque(page) ((SpGistPageOpaque) PageGetSpecialPointer(page))
#define SpGistPageIsMeta(page) (SpGistPageGetOpaque(page)->flags & SPGIST_META)
#define SpGistPageIsDeleted(page) (SpGistPageGetOpaque(page)->flags & SPGIST_DELETED)
#define SpGistPageSetDeleted(page) (SpGistPageGetOpaque(page)->flags |= SPGIST_DELETED)
#define SpGistPageIsLeaf(page) (SpGistPageGetOpaque(page)->flags & SPGIST_LEAF)
#define SpGistPageStoresNulls(page) (SpGistPageGetOpaque(page)->flags & SPGIST_NULLS)