Github user weinan003 commented on a diff in the pull request:
https://github.com/apache/incubator-hawq/pull/1350#discussion_r178480561
--- Diff: contrib/vexecutor/execVQual.c ---
@@ -0,0 +1,125 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+#include "execVQual.h"
+
+/*
+ * ExecVariableList
+ * Evaluates a simple-Variable-list projection.
+ *
+ * Results are stored into the passed values and isnull arrays.
+ */
+static void
+ExecVecVariableList(ProjectionInfo *projInfo,
+ Datum *values)
+{
+ ExprContext *econtext = projInfo->pi_exprContext;
+ int *varSlotOffsets = projInfo->pi_varSlotOffsets;
+ int *varNumbers = projInfo->pi_varNumbers;
+ TupleBatch tb = (TupleBatch) values;
+ int i;
+ tb->ncols = list_length(projInfo->pi_targetlist);
+
+ /*
+ * Assign to result by direct extraction of fields from source slots
... a
+ * mite ugly, but fast ...
+ */
+ for (i = list_length(projInfo->pi_targetlist) - 1; i >= 0; i--)
+ {
+ char *slotptr = ((char *) econtext) + varSlotOffsets[i];
+ TupleTableSlot *varSlot = *((TupleTableSlot **) slotptr);
+ int varNumber = varNumbers[i] - 1;
+ tb->datagroup[i] =
((TupleBatch)varSlot->PRIVATE_tb)->datagroup[varNumber];
+ }
+}
+
+TupleTableSlot *
+ExecVProject(ProjectionInfo *projInfo, ExprDoneCond *isDone)
+{
+ TupleTableSlot *slot;
+ Assert(projInfo != NULL);
+
+ /*
+ * get the projection info we want
+ */
+ slot = projInfo->pi_slot;
+
+ /*
+ * Clear any former contents of the result slot. This makes it safe
for
+ * us to use the slot's Datum/isnull arrays as workspace. (Also, we can
+ * return the slot as-is if we decide no rows can be projected.)
+ */
+ ExecClearTuple(slot);
+
+ /*
+ * form a new result tuple (if possible); if successful, mark the
result
+ * slot as containing a valid virtual tuple
+ */
+ if (projInfo->pi_isVarList)
+ {
+ /* simple Var list: this always succeeds with one result row */
+ if (isDone)
+ *isDone = ExprSingleResult;
+
+ ExecVecVariableList(projInfo,slot->PRIVATE_tb);
+ ExecStoreVirtualTuple(slot);
+ }
+ else
+ {
+ elog(FATAL,"does not support expression in projection stmt");
--- End diff --
The expression op will be supported soon in next
---
