postgres.git / summary / log / commit / refs

commit    83158f74d3ab8dd48aed92e84b6207562992d13d
Author:   Michael Paquier <michael@paquier.xyz>
Date:     Mon Sep 14 04:56:41 2020 +0000
First released in: 14.0

    Make index_set_state_flags() transactional
    
    3c84046 is the original commit that introduced index_set_state_flags(),
    where the presence of SnapshotNow made necessary the use of an in-place
    update.  SnapshotNow has been removed in 813fb03, so there is no actual
    reasons to not make this operation transactional.
    
    Note that while making the operation more robust, using a transactional
    operation in this routine was not strictly necessary as there was no use
    case for it yet.  However, some future features are going to need a
    transactional behavior, like support for CREATE/DROP INDEX CONCURRENTLY
    with partitioned tables, where indexes in a partition tree need to have
    all their pg_index.indis* flags updated in the same transaction to make
    the operation stable to the end-user by keeping partition trees
    consistent, even with a failure mid-flight.
    
    REINDEX CONCURRENTLY uses already transactional updates when swapping
    the old and new indexes, making this change more consistent with the
    index-swapping logic.
    
    Author: Michael Paquier
    Reviewed-by: Anastasia Lubennikova
    Discussion: https://postgr.es/m/20200903080440.GA8559@paquier.xyz


 src/backend/catalog/index.c | 19 ++++---------------
 1 file changed, 4 insertions(+), 15 deletions(-)

diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 117e3fdef7d..0974f3e23a2 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -3311,18 +3311,10 @@ validate_index_callback(ItemPointer itemptr, void *opaque)
  * index_set_state_flags - adjust pg_index state flags
  *
  * This is used during CREATE/DROP INDEX CONCURRENTLY to adjust the pg_index
- * flags that denote the index's state.  Because the update is not
- * transactional and will not roll back on error, this must only be used as
- * the last step in a transaction that has not made any transactional catalog
- * updates!
+ * flags that denote the index's state.
  *
- * Note that heap_inplace_update does send a cache inval message for the
+ * Note that CatalogTupleUpdate() sends a cache invalidation message for the
  * tuple, so other sessions will hear about the update as soon as we commit.
- *
- * NB: In releases prior to PostgreSQL 9.4, the use of a non-transactional
- * update here would have been unsafe; now that MVCC rules apply even for
- * system catalog scans, we could potentially use a transactional update here
- * instead.
  */
 void
 index_set_state_flags(Oid indexId, IndexStateFlagsAction action)
@@ -3331,9 +3323,6 @@ index_set_state_flags(Oid indexId, IndexStateFlagsAction action)
 	HeapTuple	indexTuple;
 	Form_pg_index indexForm;
 
-	/* Assert that current xact hasn't done any transactional updates */
-	Assert(GetTopTransactionIdIfAny() == InvalidTransactionId);
-
 	/* Open pg_index and fetch a writable copy of the index's tuple */
 	pg_index = table_open(IndexRelationId, RowExclusiveLock);
 
@@ -3397,8 +3386,8 @@ index_set_state_flags(Oid indexId, IndexStateFlagsAction action)
 			break;
 	}
 
-	/* ... and write it back in-place */
-	heap_inplace_update(pg_index, indexTuple);
+	/* ... and update it */
+	CatalogTupleUpdate(pg_index, &indexTuple->t_self, indexTuple);
 
 	table_close(pg_index, RowExclusiveLock);
 }


[parent: 3e0242b24c3c]