Function ExecGetUpdateNewTuple

src/backend/executor/nodeModifyTable.c:623–640

* ExecGetUpdateNewTuple * This prepares a "new" tuple by combining an UPDATE subplan's output * tuple (which contains values of changed columns) with unchanged * columns taken from the old tuple. * * The subplan tuple might also contain junk columns, which are ignored. * Note that the projection also ensures we have a slot of the right type. */

 * Note that the projection also ensures we have a slot of the right type.
 */
TupleTableSlot *
ExecGetUpdateNewTuple(ResultRelInfo *relinfo,
					  TupleTableSlot *planSlot,
					  TupleTableSlot *oldSlot)
{
	ProjectionInfo *newProj = relinfo->ri_projectNew;
	ExprContext *econtext;

	/* Use a few extra Asserts to protect against outside callers */
	Assert(relinfo->ri_projectNewInfoValid);
	Assert(planSlot != NULL && !TTS_EMPTY(planSlot));
	Assert(oldSlot != NULL && !TTS_EMPTY(oldSlot));

	econtext = newProj->pi_exprContext;
	econtext->ecxt_outertuple = planSlot;
	econtext->ecxt_scantuple = oldSlot;
	return ExecProject(newProj);
}


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