Function GinBsonExtractQueryLess

pg_documentdb/src/opclass/bson_gin_core.c:2307–2360

* GinBsonExtractQueryLess generates the index term needed to match * $lg and $lte on a dotted path and value. * In this case, We return a lower bound value of the min value for that path. * Since we set the PartialMatch value to be true, the min value will be considered * a lower bound for the indexed search. * We also pass 'extraData' being the value being queried. This will later be treated

 * i.e. a BsonElement.
 */
static Datum *
GinBsonExtractQueryLess(BsonExtractQueryArgs *args, bool isNegation)
{
	int32 *nentries = args->nentries;
	bool **partialmatch = args->partialmatch;
	Pointer **extra_data = args->extra_data;
	Datum *entries;
	pgbsonelement documentElement = args->filterElement;

	/* Clone it for now */
	pgbsonelement queryElement = documentElement;

	int numEntries = isNegation ? 5 : 2;
	entries = (Datum *) palloc(sizeof(Datum) * numEntries);
	*partialmatch = (bool *) palloc(sizeof(bool) * numEntries);
	*nentries = 1;
	(*partialmatch)[0] = true;

	/* store the query value in extra data - this allows us to compute upper bound using */
	/* this extra value. */

	/* Also serialize the actual index term */
	BsonIndexTermSerialized serializedTerm =
		SerializeBsonIndexTerm(&queryElement, &args->termMetadata);

	*extra_data = (Pointer *) palloc0(sizeof(Pointer) * numEntries);
	(*extra_data)[0] = (Pointer) serializedTerm.indexTermVal;

	/* now create a bson for that path which has the min value for the field */
	/* Today we set this as the min value for the equivalent */
	/* type (i.e. the lowest possible value for that type OR the highest possible value of the prior type) */
	/* When we don't have the table of these values, we safely start out with Minkey. */
	documentElement.bsonValue = GetLowerBoundForLessThan(
		queryElement.bsonValue.value_type);
	entries[0] = PointerGetDatum(SerializeBsonIndexTerm(&documentElement,
														&args->termMetadata).
								 indexTermVal);

	/* In the case where we have truncation, also track equality on $lt */
	if (serializedTerm.isIndexTermTruncated || isNegation)
	{
		*nentries = 2;
		(*partialmatch)[1] = false;
		entries[1] = PointerGetDatum(serializedTerm.indexTermVal);
	}

	if (isNegation)
	{
		GenerateNegationTerms(entries, *nentries, *partialmatch, &args->termMetadata);
		*nentries += 3;
	}

	return entries;
}


/*