database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-10-21 02:52:47 +03:00
Code Activity

tableam: Add helper for indexes to check if a corresponding table tuples exist.

Browse Source 
This is, likely exclusively, useful to verify that conflicts detected
in a unique index are with live tuples, rather than dead ones.

Author: Andres Freund
Discussion: https://postgr.es/m/20180703070645.wchpu5muyto5n647@alap3.anarazel.de
This commit is contained in:
Andres Freund
2019-03-25 16:52:55 -07:00
parent aa1419e63f
commit 71bdc99d0d
4 changed files with 64 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files

25
src/include/access/tableam.h
View File

@@ -256,9 +256,10 @@ typedef struct TableAmRoutine
* needs be set to true by index_fetch_tuple, signalling to the caller
* that index_fetch_tuple should be called again for the same tid.
*
* *all_dead should be set to true by index_fetch_tuple iff it is
* guaranteed that no backend needs to see that tuple. Index AMs can use
* that do avoid returning that tid in future searches.
* *all_dead, if all_dead is not NULL, should be set to true if by
* index_fetch_tuple iff it is guaranteed that no backend needs to see
* that tuple. Index AMs can use that do avoid returning that tid in
* future searches.
*/
bool (*index_fetch_tuple) (struct IndexFetchTableData *scan,
ItemPointer tid,
@@ -594,9 +595,10 @@ table_index_fetch_end(struct IndexFetchTableData *scan)
* will be set to true, signalling that table_index_fetch_tuple() should be called
* again for the same tid.
*
* *all_dead will be set to true by table_index_fetch_tuple() iff it is guaranteed
* that no backend needs to see that tuple. Index AMs can use that do avoid
* returning that tid in future searches.
* *all_dead, if all_dead is not NULL, will be set to true by
* table_index_fetch_tuple() iff it is guaranteed that no backend needs to see
* that tuple. Index AMs can use that do avoid returning that tid in future
* searches.
*
* The difference between this function and table_fetch_row_version is that
* this function returns the currently visible version of a row if the AM
@@ -618,6 +620,17 @@ table_index_fetch_tuple(struct IndexFetchTableData *scan,
all_dead);
}
/*
* This is a convenience wrapper around table_index_fetch_tuple() which
* returns whether there are table tuple items corresponding to an index
* entry. This likely is only useful to verify if there's a conflict in a
* unique index.
*/
extern bool table_index_fetch_tuple_check(Relation rel,
ItemPointer tid,
Snapshot snapshot,
bool *all_dead);
/* ------------------------------------------------------------------------
* Functions for non-modifying operations on individual tuples