Function bson_dollar_range

pg_documentdb/src/query/bson_dollar_operators.c:1281–1355

* bson_dollar_range implements the DocumentDB API's version of the range * functionality in the runtime. Note that this is different from * $range array operator. This combines $gt and $lt conditions into a range * operator that can be used to traverse an index efficiently. * * The runtime version is needed if the index requires a recheck of * the range condition. It traverses the document b

 *
 */
Datum
bson_dollar_range(PG_FUNCTION_ARGS)
{
	pgbson *document = PG_GETARG_PGBSON(0);
	pgbson *filter = PG_GETARG_PGBSON(1);
	const DollarRangeParams *cachedRangeParamsState;
	SetCachedFunctionState(
		cachedRangeParamsState,
		DollarRangeParams,
		1,
		PopulateRangeStateFromQuery,
		filter);

	DollarRangeParams localState = { 0 };
	if (cachedRangeParamsState == NULL)
	{
		PopulateRangeStateFromQuery(&localState, filter);
		cachedRangeParamsState = &localState;
	}

	TraverseRangeValidateState rangeState = { 0 };

	/*
	 *  params (i.e., DollarRangeParams) remains unchanged throughout multiple invocations of bson_dollar_range()
	 *  during the execution of a query. The rest can be modified as the query execution progresses.
	 *
	 *  We only use cached values for the unchanged parts.
	 */

	pgbsonelement filterElement;
	const char *collationString = PgbsonToSinglePgbsonElementWithCollation(filter,
																		   &filterElement);

	if (IsCollationValid(collationString))
	{
		/* TODO (workitem=3423305): Index pushdwon on $range operator with collation (see method description for more details) */
		/* This code path is not expected to be excercised until $range with collation is pushed down to the index. */
		ereport(ERROR, (errcode(ERRCODE_DOCUMENTDB_INTERNALERROR), errmsg(
							"operator $range or operators that can be optimized to $range is not supported with collation"),
						errdetail_log(
							"operator $range or operators that can be optimized to $range is not supported with collation : %s",
							collationString)));
	}

	rangeState.elementState.filter = &filterElement;
	rangeState.params = *cachedRangeParamsState;
	rangeState.isMinConditionSet = false;
	rangeState.isMaxConditionSet = false;

	if (rangeState.params.isFullScan || rangeState.params.isElemMatch)
	{
		/* if the range is a full scan, we don't need to traverse the document
		 * similarly for $elemMatch this range query is only used on the index
		 * so we bypass the runtime recheck and let the runtime filter handle it.
		 */
		PG_RETURN_BOOL(true);
	}