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Remove btree page items after page unlink

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Currently, page unlink leaves remaining items "as is", but replay of
corresponding WAL-record re-initializes page leaving it with no items.
For the sake of consistency, this commit makes primary delete all the items
during page unlink as well.

Thanks to this change, we now don't mask contents of deleted btree page for
WAL consistency checking.

Discussion: https://postgr.es/m/CAPpHfdt_OTyQpXaPJcWzV2N-LNeNJseNB-K_A66qG%3DL518VTFw%40mail.gmail.com
Author: Alexander Korotkov
Reviewed-by: Peter Geoghegan
This commit is contained in:
Alexander Korotkov
2020-08-05 02:15:34 +03:00
parent 0f76294260
commit f47b5e1395
3 changed files with 12 additions and 14 deletions
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9
src/backend/access/nbtree/nbtpage.c
View File

@@ -2058,6 +2058,7 @@ _bt_unlink_halfdead_page(Relation rel, Buffer leafbuf, BlockNumber scanblkno,
BTMetaPageData *metad = NULL;
ItemId itemid;
Page page;
PageHeader header;
BTPageOpaque opaque;
bool rightsib_is_rightmost;
int targetlevel;
@@ -2327,6 +2328,14 @@ _bt_unlink_halfdead_page(Relation rel, Buffer leafbuf, BlockNumber scanblkno,
opaque->btpo_flags |= BTP_DELETED;
opaque->btpo.xact = ReadNewTransactionId();
/*
* Remove the remaining tuples on the page. This keeps things simple for
* WAL consistency checking.
*/
header = (PageHeader) page;
header->pd_lower = SizeOfPageHeaderData;
header->pd_upper = header->pd_special;
/* And update the metapage, if needed */
if (BufferIsValid(metabuf))
{

10
src/backend/access/nbtree/nbtxlog.c
View File

@@ -1051,15 +1051,7 @@ btree_mask(char *pagedata, BlockNumber blkno)
maskopaq = (BTPageOpaque) PageGetSpecialPointer(page);
if (P_ISDELETED(maskopaq))
{
/*
* Mask page content on a DELETED page since it will be re-initialized
* during replay. See btree_xlog_unlink_page() for details.
*/
mask_page_content(page);
}
else if (P_ISLEAF(maskopaq))
if (P_ISLEAF(maskopaq))
{
/*
* In btree leaf pages, it is possible to modify the LP_FLAGS without