From bc09288651bbda0cfca1a4909a4a5c0ca4e3e55f Mon Sep 17 00:00:00 2001
From: Onder Kalaci <onderkalaci@gmail.com>
Date: Wed, 16 Jun 2021 12:23:43 +0300
Subject: [PATCH] Get ready for Improve index backed constraint creation for
 online rebalancer

See:
https://github.com/citusdata/citus-enterprise/issues/616
---
 .../distributed/operations/node_protocol.c    | 32 +++++++++++--------
 .../distributed/coordinator_protocol.h        |  6 ++--
 2 files changed, 22 insertions(+), 16 deletions(-)

diff --git a/src/backend/distributed/operations/node_protocol.c b/src/backend/distributed/operations/node_protocol.c
index c52f6efcf..f0ff1c82b 100644
--- a/src/backend/distributed/operations/node_protocol.c
+++ b/src/backend/distributed/operations/node_protocol.c
@@ -799,28 +799,32 @@ GatherIndexAndConstraintDefinitionList(Form_pg_index indexForm, List **indexDDLE
 									   int indexFlags)
 {
 	Oid indexId = indexForm->indexrelid;
-	char *statementDef = NULL;
-
 	bool indexImpliedByConstraint = IndexImpliedByAConstraint(indexForm);
 
 	/* get the corresponding constraint or index statement */
 	if (indexImpliedByConstraint)
 	{
-		Oid constraintId = get_index_constraint(indexId);
-		Assert(constraintId != InvalidOid);
+		if (indexFlags & INCLUDE_CREATE_CONSTRAINT_STATEMENTS)
+		{
+			Oid constraintId = get_index_constraint(indexId);
+			Assert(constraintId != InvalidOid);
 
-		statementDef = pg_get_constraintdef_command(constraintId);
+			/* include constraints backed by indexes only when explicitly asked */
+			char *statementDef = pg_get_constraintdef_command(constraintId);
+			*indexDDLEventList =
+				lappend(*indexDDLEventList,
+						makeTableDDLCommandString(statementDef));
+		}
 	}
-	else
+	else if (indexFlags & INCLUDE_CREATE_INDEX_STATEMENTS)
 	{
-		statementDef = pg_get_indexdef_string(indexId);
-	}
-
-	/* append found constraint or index definition to the list */
-	if (indexFlags & INCLUDE_CREATE_INDEX_STATEMENTS)
-	{
-		*indexDDLEventList = lappend(*indexDDLEventList, makeTableDDLCommandString(
-										 statementDef));
+		/*
+		 * Include indexes that are not backing constraints only when
+		 * explicitly asked.
+		 */
+		char *statementDef = pg_get_indexdef_string(indexId);
+		*indexDDLEventList = lappend(*indexDDLEventList,
+									 makeTableDDLCommandString(statementDef));
 	}
 
 	/* if table is clustered on this index, append definition to the list */
diff --git a/src/include/distributed/coordinator_protocol.h b/src/include/distributed/coordinator_protocol.h
index ab5490fca..7f43138d2 100644
--- a/src/include/distributed/coordinator_protocol.h
+++ b/src/include/distributed/coordinator_protocol.h
@@ -101,9 +101,11 @@ typedef enum TableDDLCommandType
 typedef enum IndexDefinitionDeparseFlags
 {
 	INCLUDE_CREATE_INDEX_STATEMENTS = 1 << 0,
-	INCLUDE_INDEX_CLUSTERED_STATEMENTS = 1 << 1,
-	INCLUDE_INDEX_STATISTICS_STATEMENTTS = 1 << 2,
+	INCLUDE_CREATE_CONSTRAINT_STATEMENTS = 1 << 1,
+	INCLUDE_INDEX_CLUSTERED_STATEMENTS = 1 << 2,
+	INCLUDE_INDEX_STATISTICS_STATEMENTTS = 1 << 3,
 	INCLUDE_INDEX_ALL_STATEMENTS = INCLUDE_CREATE_INDEX_STATEMENTS |
+								   INCLUDE_CREATE_CONSTRAINT_STATEMENTS |
 								   INCLUDE_INDEX_CLUSTERED_STATEMENTS |
 								   INCLUDE_INDEX_STATISTICS_STATEMENTTS
 } IndexDefinitionDeparseFlags;