Function DensifyDocsFromState

pg_documentdb/src/aggregation/bson_densify.c:951–1080

* DensifyDocsFromState returns an array pgbson with the current document and all other * documents added to densify the list * e.g. * document = {b: 10, a: 1} * step = { "": 2 } * minValue = {"": 6} * maxValue = {"": 14} * then this function would return: * if document is the last row in the group then * {"_": [ {b: 6}, {b: 8}, {b: 10, a: 1}, {b: 12}, {b: 14} ]} * * otherwise densifies

 * If the time unit is present the returned array is date values.
 */
static pgbson *
DensifyDocsFromState(const pgbson *document, bson_value_t *minValue,
					 bson_value_t *maxValue,
					 const pgbson *partitionBy, DensifyWindowState *state)
{
	pgbson_writer writer;
	PgbsonWriterInit(&writer);
	pgbson_array_writer arrayWriter;
	PgbsonWriterStartArray(&writer, DENSIFY_RESULT_FIELD,
						   DENSIFY_RESULT_FIELD_LENGTH, &arrayWriter);

	bool includeMaxBound = false;
	bson_value_t lastMinUpdatedValue = { 0 };
	bson_value_t currentFieldValue = { 0 };

	DensifyArguments *arguments = &state->arguments;
	PartitionAwareState *partitionState = &state->partitionAwareState;

	if (!partitionState->skipRows)
	{
		if (document != NULL)
		{
			PgbsonGetBsonValueAtPath(document, arguments->field.string,
									 &currentFieldValue);
			CheckFieldValue(&currentFieldValue, state);
		}

		bool overflowedFromInt = false;
		bool isComparisionValid = true;
		int upperBoundCompareResult = maxValue->value_type == BSON_TYPE_EOD ? -1 :
									  CompareBsonValueAndType(&currentFieldValue,
															  maxValue,
															  &overflowedFromInt);

		if (minValue->value_type == BSON_TYPE_EOD ||
			minValue->value_type == BSON_TYPE_NULL)
		{
			/*
			 * Generally EOD and NULL values are placed before regular values in an ASC sort
			 * so whenever the minValue is any of these we can make the min=currentFieldValue
			 * and write the document.
			 * By doing this we progress till we start finding regular value where densification
			 * can be done
			 */
			*minValue = currentFieldValue;
		}

		int compareResult = CompareBsonValueAndType(&currentFieldValue, minValue,
													&isComparisionValid);

		if (upperBoundCompareResult > 0)
		{
			/* Doc is out of upper bound add all pending step values and mark the state to skip rows for next set of documents */
			partitionState->skipRows = true;
			lastMinUpdatedValue = GenerateAndWriteDocumentsInRange(minValue, maxValue,
																   partitionBy, state,
																   &arrayWriter,
																   includeMaxBound);