Subject: [PATCH v50 1/8] Make index_concurrently_create_copy more general

From: Álvaro Herrera <[email-masked]>
Date: Tue, 24 Mar 2026 19:02:58 +0100

Add a 'boolean concurrent' option, and make it work for both cases.
Also rename it to index_create_copy.

This allows it to be reused for other purposes -- specifically, for
REPACK CONCURRENTLY.

With the CONCURRENTLY option, REPACK cannot simply swap the heap file and
rebuild its indexes. Instead, it needs to build a separate set of indexes
(including system catalog entries) *before* the actual swap, to reduce the
time AccessExclusiveLock needs to be held for.  This approach is
different from what CREATE INDEX CONCURRENTLY does.

Per a suggestion from Mihail Nikalayeu.

Author: Antonin Houska <[email-masked]>
Discussion: https://postgr.es/m/41104.1754922120@localhost
---
 src/backend/catalog/index.c      | 41 ++++++++++++++++++++++----------
 src/backend/commands/indexcmds.c |  9 +++----
 src/include/catalog/index.h      |  7 +++---
 3 files changed, 36 insertions(+), 21 deletions(-)

diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 1ccfa687f05..e418d67e8e4 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -1289,17 +1289,17 @@ index_create(Relation heapRelation,
 }
 
 /*
- * index_concurrently_create_copy
+ * index_create_copy
  *
- * Create concurrently an index based on the definition of the one provided by
- * caller.  The index is inserted into catalogs and needs to be built later
- * on.  This is called during concurrent reindex processing.
+ * Create an index based on the definition of the one provided by caller.  The
+ * index is inserted into catalogs. If 'concurrently' is TRUE, it needs to be
+ * built later on; otherwise it's built immediately.
  *
  * "tablespaceOid" is the tablespace to use for this index.
  */
 Oid
-index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId,
-							   Oid tablespaceOid, const char *newName)
+index_create_copy(Relation heapRelation, bool concurrently,
+				  Oid oldIndexId, Oid tablespaceOid, const char *newName)
 {
 	Relation	indexRelation;
 	IndexInfo  *oldInfo,
@@ -1318,6 +1318,7 @@ index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId,
 	List	   *indexColNames = NIL;
 	List	   *indexExprs = NIL;
 	List	   *indexPreds = NIL;
+	int			flags = 0;
 
 	indexRelation = index_open(oldIndexId, RowExclusiveLock);
 
@@ -1328,7 +1329,7 @@ index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId,
 	 * Concurrent build of an index with exclusion constraints is not
 	 * supported.
 	 */
-	if (oldInfo->ii_ExclusionOps != NULL)
+	if (oldInfo->ii_ExclusionOps != NULL && concurrently)
 		ereport(ERROR,
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				 errmsg("concurrent index creation for exclusion constraints is not supported")));
@@ -1384,9 +1385,7 @@ index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId,
 	}
 
 	/*
-	 * Build the index information for the new index.  Note that rebuild of
-	 * indexes with exclusion constraints is not supported, hence there is no
-	 * need to fill all the ii_Exclusion* fields.
+	 * Build the index information for the new index.
 	 */
 	newInfo = makeIndexInfo(oldInfo->ii_NumIndexAttrs,
 							oldInfo->ii_NumIndexKeyAttrs,
@@ -1395,11 +1394,24 @@ index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId,
 							indexPreds,
 							oldInfo->ii_Unique,
 							oldInfo->ii_NullsNotDistinct,
-							false,	/* not ready for inserts */
-							true,
+							!concurrently,	/* isready */
+							concurrently,	/* concurrent */
 							indexRelation->rd_indam->amsummarizing,
 							oldInfo->ii_WithoutOverlaps);
 
+	/* fetch exclusion constraint info if any */
+	if (indexRelation->rd_index->indisexclusion)
+	{
+		/*
+		 * XXX Beware: we're making newInfo point to oldInfo-owned memory.  It
+		 * would be more orthodox to palloc+memcpy, but we don't need that
+		 * here at present.
+		 */
+		newInfo->ii_ExclusionOps = oldInfo->ii_ExclusionOps;
+		newInfo->ii_ExclusionProcs = oldInfo->ii_ExclusionProcs;
+		newInfo->ii_ExclusionStrats = oldInfo->ii_ExclusionStrats;
+	}
+
 	/*
 	 * Extract the list of column names and the column numbers for the new
 	 * index information.  All this information will be used for the index
@@ -1436,6 +1448,9 @@ index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId,
 		stattargets[i].isnull = isnull;
 	}
 
+	if (concurrently)
+		flags = INDEX_CREATE_SKIP_BUILD | INDEX_CREATE_CONCURRENT;
+
 	/*
 	 * Now create the new index.
 	 *
@@ -1459,7 +1474,7 @@ index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId,
 							  indcoloptions->values,
 							  stattargets,
 							  reloptionsDatum,
-							  INDEX_CREATE_SKIP_BUILD | INDEX_CREATE_CONCURRENT,
+							  flags,
 							  0,
 							  true, /* allow table to be a system catalog? */
 							  false,	/* is_internal? */
diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index 373e8234794..cba379810c7 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -3989,10 +3989,11 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 			tablespaceid = indexRel->rd_rel->reltablespace;
 
 		/* Create new index definition based on given index */
-		newIndexId = index_concurrently_create_copy(heapRel,
-													idx->indexId,
-													tablespaceid,
-													concurrentName);
+		newIndexId = index_create_copy(heapRel,
+									   true,
+									   idx->indexId,
+									   tablespaceid,
+									   concurrentName);
 
 		/*
 		 * Now open the relation of the new index, a session-level lock is
diff --git a/src/include/catalog/index.h b/src/include/catalog/index.h
index a38e95bc0eb..ed9e4c37d27 100644
--- a/src/include/catalog/index.h
+++ b/src/include/catalog/index.h
@@ -101,10 +101,9 @@ extern Oid	index_create(Relation heapRelation,
 #define	INDEX_CONSTR_CREATE_REMOVE_OLD_DEPS	(1 << 4)
 #define	INDEX_CONSTR_CREATE_WITHOUT_OVERLAPS (1 << 5)
 
-extern Oid	index_concurrently_create_copy(Relation heapRelation,
-										   Oid oldIndexId,
-										   Oid tablespaceOid,
-										   const char *newName);
+extern Oid	index_create_copy(Relation heapRelation, bool concurrently,
+							  Oid oldIndexId, Oid tablespaceOid,
+							  const char *newName);
 
 extern void index_concurrently_build(Oid heapRelationId,
 									 Oid indexRelationId);
-- 
2.47.3

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