Function ExecInitSplitUpdate

src/backend/executor/nodeSplitUpdate.c:219–280

* Init SplitUpdate Node. A memory context is created to hold Split Tuples. * */

 * Init SplitUpdate Node. A memory context is created to hold Split Tuples.
 * */
SplitUpdateState*
ExecInitSplitUpdate(SplitUpdate *node, EState *estate, int eflags)
{
	SplitUpdateState *splitupdatestate;

	/* Check for unsupported flags */
	Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK | EXEC_FLAG_REWIND)));

	splitupdatestate = makeNode(SplitUpdateState);
	splitupdatestate->ps.plan = (Plan *)node;
	splitupdatestate->ps.state = estate;
	splitupdatestate->ps.ExecProcNode = ExecSplitUpdate;
	splitupdatestate->processInsert = true;

	/*
	 * then initialize outer plan
	 */
	Plan *outerPlan = outerPlan(node);
	outerPlanState(splitupdatestate) = ExecInitNode(outerPlan, estate, eflags);

	ExecAssignExprContext(estate, &splitupdatestate->ps);

	/*
	 * New TupleDescriptor for output TupleTableSlots (old_values + new_values, ctid,
	 * gp_segment, action).
	 */
	TupleDesc tupDesc = ExecTypeFromTL(node->plan.targetlist);
	splitupdatestate->insertTuple = ExecInitExtraTupleSlot(estate, tupDesc, &TTSOpsVirtual);
	splitupdatestate->deleteTuple = ExecInitExtraTupleSlot(estate, tupDesc, &TTSOpsVirtual);

	/*
	 * Look up the positions of the gp_segment_id in the subplan's target
	 * list, and in the result.
	 */
	splitupdatestate->input_segid_attno =
		ExecFindJunkAttributeInTlist(outerPlan->targetlist, "gp_segment_id");
	splitupdatestate->output_segid_attno =
		ExecFindJunkAttributeInTlist(node->plan.targetlist, "gp_segment_id");

	/*
	 * DML nodes do not project.
	 */
	ExecInitResultTupleSlotTL(&splitupdatestate->ps, &TTSOpsVirtual);
	splitupdatestate->ps.ps_ProjInfo = NULL;

	/*
	 * Initialize for computing hash key
	 */
	if (node->numHashAttrs > 0)
	{
		splitupdatestate->cdbhash = makeCdbHash(node->numHashSegments,
												node->numHashAttrs,
												node->hashFuncs);
	}

	if (estate->es_instrument && (estate->es_instrument & INSTRUMENT_CDB))
	{
		splitupdatestate->ps.cdbexplainbuf = makeStringInfo();