Function ExecPartitionCheck

src/backend/executor/execMain.c:2959–3006

* ExecPartitionCheck --- check that tuple meets the partition constraint. * * Returns true if it meets the partition constraint. If the constraint * fails and we're asked to emit an error, do so and don't return; otherwise * return false. */

 * return false.
 */
bool
ExecPartitionCheck(ResultRelInfo *resultRelInfo, TupleTableSlot *slot,
				   EState *estate, bool emitError)
{
	ExprContext *econtext;
	bool		success;

	/*
	 * If first time through, build expression state tree for the partition
	 * check expression.  (In the corner case where the partition check
	 * expression is empty, ie there's a default partition and nothing else,
	 * we'll be fooled into executing this code each time through.  But it's
	 * pretty darn cheap in that case, so we don't worry about it.)
	 */
	if (resultRelInfo->ri_PartitionCheckExpr == NULL)
	{
		/*
		 * Ensure that the qual tree and prepared expression are in the
		 * query-lifespan context.
		 */
		MemoryContext oldcxt = MemoryContextSwitchTo(estate->es_query_cxt);
		List	   *qual = RelationGetPartitionQual(resultRelInfo->ri_RelationDesc);

		resultRelInfo->ri_PartitionCheckExpr = ExecPrepareCheck(qual, estate);
		MemoryContextSwitchTo(oldcxt);
	}

	/*
	 * We will use the EState's per-tuple context for evaluating constraint
	 * expressions (creating it if it's not already there).
	 */
	econtext = GetPerTupleExprContext(estate);

	/* Arrange for econtext's scan tuple to be the tuple under test */
	econtext->ecxt_scantuple = slot;

	/*
	 * As in case of the catalogued constraints, we treat a NULL result as
	 * success here, not a failure.
	 */
	success = ExecCheck(resultRelInfo->ri_PartitionCheckExpr, econtext);

	/* if asked to emit error, don't actually return on failure */
	if (!success && emitError)
		ExecPartitionCheckEmitError(resultRelInfo, slot, estate);

	return success;
}

/*
 * ExecPartitionCheckEmitError - Form and emit an error message after a failed