Always allocate DynamicTableScanInfo in es_query_cxt.

DynamicTableScanInfo is an extension of EState, so always allocate it in the
same memory context. The DynamicTableScanInfo.memoryContext field always
pointed to es_query_cxt, so that is what we in fact always did anyway, this
just removes the unnecessary abstraction, for simplicity.

src/backend/executor/execMain.c

@@ -1559,10 +1559,9 @@ InitializeQueryPartsMetadata(PlannedStmt *plannedstmt, EState *estate)
 	}
 	
 	/* Populate the partitioning metadata to EState */
-	Assert(estate->dynamicTableScanInfo != NULL &&
-		   estate->dynamicTableScanInfo->memoryContext != NULL);
+	Assert(estate->dynamicTableScanInfo != NULL);
 	
-	MemoryContext oldContext = MemoryContextSwitchTo(estate->dynamicTableScanInfo->memoryContext);
+	MemoryContext oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
 	
 	ListCell *lc = NULL;
 	foreach(lc, plannedstmt->queryPartsMetadata)

src/backend/executor/execUtils.c

@@ -196,7 +196,6 @@ CreateExecutorState(void)
 	 * Initialize dynamicTableScanInfo.
 	 */
 	estate->dynamicTableScanInfo = palloc0(sizeof(DynamicTableScanInfo));
-	estate->dynamicTableScanInfo->memoryContext = qcontext;
 
 	/*
 	 * Initialize all fields of the Executor State structure

src/backend/executor/nodePartitionSelector.c

@@ -136,7 +136,7 @@ ExecPartitionSelector(PartitionSelectorState *node)
 									(
 									ps->relid,
 									estate->dynamicTableScanInfo->partsMetadata,
-									estate->dynamicTableScanInfo->memoryContext,
+									estate->es_query_cxt,
 									&node->rootPartitionNode,
 									&node->accessMethods
 									);

src/backend/utils/adt/gp_partition_functions.c

@@ -78,7 +78,7 @@ createPidIndex(EState *estate, int index)
 	hashCtl.keysize = sizeof(Oid);
 	hashCtl.entrysize = sizeof(PartOidEntry);
 	hashCtl.hash = oid_hash;
-	hashCtl.hcxt = estate->dynamicTableScanInfo->memoryContext;
+	hashCtl.hcxt = estate->es_query_cxt;
 
 	return hash_create("Dynamic Table Scan Pid Index",
 					   INITIAL_NUM_PIDS,
@@ -98,13 +98,12 @@ InsertPidIntoDynamicTableScanInfo(EState *estate, int32 index, Oid partOid, int3
 {
 	DynamicTableScanInfo *dynamicTableScanInfo = estate->dynamicTableScanInfo;
 
-	Assert(dynamicTableScanInfo != NULL &&
-		   dynamicTableScanInfo->memoryContext != NULL);
+	Assert(dynamicTableScanInfo != NULL);
 
 	/* It's 1 based indexing */
 	Assert(index > 0);
 
-	MemoryContext oldCxt = MemoryContextSwitchTo(dynamicTableScanInfo->memoryContext);
+	MemoryContext oldCxt = MemoryContextSwitchTo(estate->es_query_cxt);
 
 	if (index > dynamicTableScanInfo->numScans)
 	{

src/include/nodes/execnodes.h

@@ -492,11 +492,6 @@ typedef struct DynamicTableScanInfo
 	 * Partitioning metadata for all relevant partition tables.
 	 */
 	List	   *partsMetadata;
-
-	/*
-	 * The memory context in which pidIndexes are allocated.
-	 */
-	MemoryContext memoryContext;
 } DynamicTableScanInfo;
 
 /*