Function bson_distinct_unwind

pg_documentdb/src/aggregation/bson_unwind.c:163–193

* Implements the unwind function for Distinct. Walks the document for the given * dotted path, and for every element that matches the path, adds it to the tuple store * for instance, given the document { "a": [ { "b": [ 1, 2, 3, 4] }, { "b": [ 2, 4 ] }, { "b": 1 }]} for the path * "a.b", will produce a tuple store with the elements [ 1, 2, 3, 4, 2, 4, 1 ]. * This will then be passed through DI

 * This will then be passed through DISTINCT to reduce the array set.
 */
Datum
bson_distinct_unwind(PG_FUNCTION_ARGS)
{
	TupleDesc descriptor;
	Tuplestorestate *tupleStore = SetupBsonTuplestore(fcinfo, &descriptor);
	pgbson *document = PG_GETARG_PGBSON(0);
	char *path = text_to_cstring(PG_GETARG_TEXT_P(1));

	bson_iter_t documentIterator;
	PgbsonInitIterator(document, &documentIterator);
	TraverseBsonExecutionFuncs distinctExecutionFuncs =
	{
		.ContinueProcessIntermediateArray = DistinctContinueProcessIntermediateArray,
		.SetTraverseResult = DistinctSetTraverseResult,
		.VisitArrayField = DistinctVisitArrayField,
		.VisitTopLevelField = DistinctVisitTopLevelField,
		.SetIntermediateArrayIndex = NULL,
		.HandleIntermediateArrayPathNotFound = NULL,
		.SetIntermediateArrayStartEnd = NULL,
	};

	DistinctTraverseState traverseState =
	{
		.tupleDescriptor = descriptor,
		.tupleStore = tupleStore
	};

	TraverseBson(&documentIterator, path, &traverseState, &distinctExecutionFuncs);

	PG_RETURN_VOID();
}


/*