From f3f711e0975d5e373c78d48c9b6df7a6af63d3e5 Mon Sep 17 00:00:00 2001
From: Onur Tirtir <onurcantirtir@gmail.com>
Date: Thu, 4 Jun 2020 17:28:43 +0300
Subject: [PATCH] Implement IndexIsImpliedByAConstraint

---
 .../distributed/master/master_node_protocol.c | 57 ++++++++++++-------
 src/include/distributed/master_protocol.h     |  1 +
 2 files changed, 37 insertions(+), 21 deletions(-)

diff --git a/src/backend/distributed/master/master_node_protocol.c b/src/backend/distributed/master/master_node_protocol.c
index 1d03aab34..585a4be3f 100644
--- a/src/backend/distributed/master/master_node_protocol.c
+++ b/src/backend/distributed/master/master_node_protocol.c
@@ -674,31 +674,12 @@ GetTableIndexAndConstraintCommands(Oid relationId)
 	{
 		Form_pg_index indexForm = (Form_pg_index) GETSTRUCT(heapTuple);
 		Oid indexId = indexForm->indexrelid;
-		bool isConstraint = false;
 		char *statementDef = NULL;
 
-		/*
-		 * A primary key index is always created by a constraint statement.
-		 * A unique key index or exclusion index is created by a constraint
-		 * if and only if the index has a corresponding constraint entry in pg_depend.
-		 * Any other index form is never associated with a constraint.
-		 */
-		if (indexForm->indisprimary)
-		{
-			isConstraint = true;
-		}
-		else if (indexForm->indisunique || indexForm->indisexclusion)
-		{
-			Oid constraintId = get_index_constraint(indexId);
-			isConstraint = OidIsValid(constraintId);
-		}
-		else
-		{
-			isConstraint = false;
-		}
+		bool indexImpliedByConstraint = IndexImpliedByAConstraint(indexForm);
 
 		/* get the corresponding constraint or index statement */
-		if (isConstraint)
+		if (indexImpliedByConstraint)
 		{
 			Oid constraintId = get_index_constraint(indexId);
 			Assert(constraintId != InvalidOid);
@@ -736,6 +717,40 @@ GetTableIndexAndConstraintCommands(Oid relationId)
 }
 
 
+/*
+ * IndexImpliedByAConstraint is an helper function to be used while scanning
+ * pg_index. It returns true if the index identified by the given indexForm is
+ * implied by a constraint. Note that caller is responsible for passing a valid
+ * indexFrom, which means an alive heap tuple which is of form Form_pg_index.
+ */
+bool
+IndexImpliedByAConstraint(Form_pg_index indexForm)
+{
+	Assert(indexForm != NULL);
+
+	bool indexImpliedByConstraint = false;
+
+	/*
+	 * A primary key index is always created by a constraint statement.
+	 * A unique key index or exclusion index is created by a constraint
+	 * if and only if the index has a corresponding constraint entry in
+	 * pg_depend. Any other index form is never associated with a constraint.
+	 */
+	if (indexForm->indisprimary)
+	{
+		indexImpliedByConstraint = true;
+	}
+	else if (indexForm->indisunique || indexForm->indisexclusion)
+	{
+		Oid constraintId = get_index_constraint(indexForm->indexrelid);
+
+		indexImpliedByConstraint = OidIsValid(constraintId);
+	}
+
+	return indexImpliedByConstraint;
+}
+
+
 /*
  * ShardStorageType returns the shard storage type according to relation type.
  */
diff --git a/src/include/distributed/master_protocol.h b/src/include/distributed/master_protocol.h
index 1755a101d..14743a5c3 100644
--- a/src/include/distributed/master_protocol.h
+++ b/src/include/distributed/master_protocol.h
@@ -105,6 +105,7 @@ extern Oid ResolveRelationId(text *relationName, bool missingOk);
 extern List * GetTableDDLEvents(Oid relationId, bool forShardCreation);
 extern List * GetTableCreationCommands(Oid relationId, bool forShardCreation);
 extern List * GetTableIndexAndConstraintCommands(Oid relationId);
+extern bool IndexImpliedByAConstraint(Form_pg_index indexForm);
 extern char ShardStorageType(Oid relationId);
 extern void CheckDistributedTable(Oid relationId);
 extern void CreateAppendDistributedShardPlacements(Oid relationId, int64 shardId,