From da6b42a3e2eaf316945b7c5e39420d7cf899888c Mon Sep 17 00:00:00 2001
From: Marco Slot <marco.slot@gmail.com>
Date: Fri, 22 Sep 2017 20:19:51 +0200
Subject: [PATCH] Use unique constraint index for transaction record deletion

---
 .../distributed/transaction/transaction_recovery.c   |  8 +++++---
 src/backend/distributed/utils/metadata_cache.c       | 12 ++++++++++++
 src/include/distributed/metadata_cache.h             |  1 +
 3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/src/backend/distributed/transaction/transaction_recovery.c b/src/backend/distributed/transaction/transaction_recovery.c
index 93b89acb6..f3eacf848 100644
--- a/src/backend/distributed/transaction/transaction_recovery.c
+++ b/src/backend/distributed/transaction/transaction_recovery.c
@@ -478,8 +478,8 @@ DeleteTransactionRecord(int32 groupId, char *transactionName)
 {
 	Relation pgDistTransaction = NULL;
 	SysScanDesc scanDescriptor = NULL;
-	ScanKeyData scanKey[1];
-	int scanKeyCount = 1;
+	ScanKeyData scanKey[2];
+	int scanKeyCount = 2;
 	bool indexOK = true;
 	HeapTuple heapTuple = NULL;
 	bool heapTupleFound = false;
@@ -488,9 +488,11 @@ DeleteTransactionRecord(int32 groupId, char *transactionName)
 
 	ScanKeyInit(&scanKey[0], Anum_pg_dist_transaction_groupid,
 				BTEqualStrategyNumber, F_INT4EQ, Int32GetDatum(groupId));
+	ScanKeyInit(&scanKey[1], Anum_pg_dist_transaction_gid,
+				BTEqualStrategyNumber, F_TEXTEQ, CStringGetTextDatum(transactionName));
 
 	scanDescriptor = systable_beginscan(pgDistTransaction,
-										DistTransactionGroupIndexId(), indexOK,
+										DistTransactionRecordIndexId(), indexOK,
 										NULL, scanKeyCount, scanKey);
 
 	heapTuple = systable_getnext(scanDescriptor);
diff --git a/src/backend/distributed/utils/metadata_cache.c b/src/backend/distributed/utils/metadata_cache.c
index c0ef48860..e11025c02 100644
--- a/src/backend/distributed/utils/metadata_cache.c
+++ b/src/backend/distributed/utils/metadata_cache.c
@@ -113,6 +113,7 @@ typedef struct MetadataCacheData
 	Oid distPlacementGroupidIndexId;
 	Oid distTransactionRelationId;
 	Oid distTransactionGroupIndexId;
+	Oid distTransactionRecordIndexId;
 	Oid extraDataContainerFuncId;
 	Oid workerHashFunctionId;
 	Oid extensionOwner;
@@ -1796,6 +1797,17 @@ DistTransactionGroupIndexId(void)
 }
 
 
+/* return oid of pg_dist_transaction_unique_constraint */
+Oid
+DistTransactionRecordIndexId(void)
+{
+	CachedRelationLookup("pg_dist_transaction_unique_constraint",
+						 &MetadataCache.distTransactionRecordIndexId);
+
+	return MetadataCache.distTransactionRecordIndexId;
+}
+
+
 /* return oid of pg_dist_placement_groupid_index */
 Oid
 DistPlacementGroupidIndexId(void)
diff --git a/src/include/distributed/metadata_cache.h b/src/include/distributed/metadata_cache.h
index 464214a56..3caa73edb 100644
--- a/src/include/distributed/metadata_cache.h
+++ b/src/include/distributed/metadata_cache.h
@@ -117,6 +117,7 @@ extern Oid DistPlacementShardidIndexId(void);
 extern Oid DistPlacementPlacementidIndexId(void);
 extern Oid DistTransactionRelationId(void);
 extern Oid DistTransactionGroupIndexId(void);
+extern Oid DistTransactionRecordIndexId(void);
 extern Oid DistPlacementGroupidIndexId(void);
 
 /* function oids */