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Fix incorrect loop counts in tidbitmap.c.

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A couple of places that should have been iterating over WORDS_PER_CHUNK
words were iterating over WORDS_PER_PAGE words instead.  This thinko
accidentally failed to fail, because (at least on common architectures
with default BLCKSZ) WORDS_PER_CHUNK is a bit less than WORDS_PER_PAGE,
and the extra words being looked at were always zero so nothing happened.
Still, it's a bug waiting to happen if anybody ever fools with the
parameters affecting TIDBitmap sizes, and it's a small waste of cycles
too.  So back-patch to all active branches.

Etsuro Fujita
This commit is contained in:
Tom Lane 2013-11-15 18:34:14 -05:00
parent 1c0dfaa68f
commit 4b61f67837
1 changed files with 2 additions and 2 deletions
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4
src/backend/nodes/tidbitmap.c
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@ -361,7 +361,7 @@ tbm_union_page(TIDBitmap *a, const PagetableEntry *bpage)
if (bpage->ischunk) if (bpage->ischunk)
{ {
/* Scan b's chunk, mark each indicated page lossy in a */ /* Scan b's chunk, mark each indicated page lossy in a */
for (wordnum = 0; wordnum < WORDS_PER_PAGE; wordnum++) for (wordnum = 0; wordnum < WORDS_PER_CHUNK; wordnum++)
{ {
bitmapword w = bpage->words[wordnum]; bitmapword w = bpage->words[wordnum];
@ -473,7 +473,7 @@ tbm_intersect_page(TIDBitmap *a, PagetableEntry *apage, const TIDBitmap *b)
/* Scan each bit in chunk, try to clear */ /* Scan each bit in chunk, try to clear */
bool candelete = true; bool candelete = true;
for (wordnum = 0; wordnum < WORDS_PER_PAGE; wordnum++) for (wordnum = 0; wordnum < WORDS_PER_CHUNK; wordnum++)
{ {
bitmapword w = apage->words[wordnum]; bitmapword w = apage->words[wordnum];