Function evalHashKey

src/backend/executor/nodeSplitUpdate.c:40–69

* Evaluate the hash keys, and compute the target segment ID for the new row. */

 * Evaluate the hash keys, and compute the target segment ID for the new row.
 */
static uint32
evalHashKey(SplitUpdateState *node, Datum *values, bool *isnulls)
{
	SplitUpdate *plannode = (SplitUpdate *) node->ps.plan;
	ExprContext *econtext = node->ps.ps_ExprContext;
	MemoryContext oldContext;
	unsigned int target_seg;
	CdbHash	   *h = node->cdbhash;

	ResetExprContext(econtext);

	oldContext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);

	cdbhashinit(h);

	for (int i = 0; i < plannode->numHashAttrs; i++)
	{
		AttrNumber	keyattno = plannode->hashAttnos[i];

		/*
		 * Compute the hash function
		 */
		cdbhash(h, i + 1, values[keyattno - 1], isnulls[keyattno - 1]);
	}
	target_seg = cdbhashreduce(h);

	MemoryContextSwitchTo(oldContext);

	return target_seg;
}

/* Split TupleTableSlot into a DELETE and INSERT TupleTableSlot */
static void