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Add bms_next_member(), and use it where appropriate.

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This patch adds a way of iterating through the members of a bitmapset
nondestructively, unlike the old way with bms_first_member().  While
bms_next_member() is very slightly slower than bms_first_member()
(at least for typical-size bitmapsets), eliminating the need to palloc
and pfree a temporary copy of the target bitmapset is a significant win.
So this method should be preferred in all cases where a temporary copy
would be necessary.

Tom Lane, with suggestions from Dean Rasheed and David Rowley
This commit is contained in:
Tom Lane
2014-11-28 13:37:25 -05:00
parent 96d66bcfc6
commit f4e031c662
13 changed files with 114 additions and 76 deletions
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14
contrib/postgres_fdw/postgres_fdw.c
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@ -1198,15 +1198,17 @@ postgresPlanForeignModify(PlannerInfo *root,
}
else if (operation == CMD_UPDATE)
{
Bitmapset *tmpset = bms_copy(rte->modifiedCols);
AttrNumber col;
int col;
while ((col = bms_first_member(tmpset)) >= 0)
col = -1;
while ((col = bms_next_member(rte->modifiedCols, col)) >= 0)
{
col += FirstLowInvalidHeapAttributeNumber;
if (col <= InvalidAttrNumber) /* shouldn't happen */
/* bit numbers are offset by FirstLowInvalidHeapAttributeNumber */
AttrNumber attno = col + FirstLowInvalidHeapAttributeNumber;
if (attno <= InvalidAttrNumber) /* shouldn't happen */
elog(ERROR, "system-column update is not supported");
targetAttrs = lappend_int(targetAttrs, col);
targetAttrs = lappend_int(targetAttrs, attno);
}
}