Method estimateMemUsageForBatch

query/aql_processor.go:1112–1163

estimateMemUsageForBatch calculates memory usage including: * Index vector * Predicate vector * Dimension * Measurement * Sort (hash/index) * Reduce

(firstColumnSize, columnMemUsage, maxSizeAfterPreFilter int)

// * Sort (hash/index)
// * Reduce
func (qc *AQLQueryContext) estimateMemUsageForBatch(firstColumnSize, columnMemUsage, maxSizeAfterPreFilter int) (memUsage int) {
	// 1. columnMemUsage
	memUsageBeforeAgg := columnMemUsage

	// 2. index vector memory usage (4 bytes each)
	memUsageBeforeAgg += firstColumnSize * 4

	// 3. predicate memory usage (1 byte each)
	memUsageBeforeAgg += firstColumnSize

	// 4. record id vector for foreign table (8 bytes each recordID)
	memUsageBeforeAgg += firstColumnSize * 8 * len(qc.OOPK.foreignTables)

	// 5. expression eval memory (max scratch space)
	memUsageBeforeAgg += qc.estimateExpressionEvaluationMemUsage(firstColumnSize)

	// 6. geoPredicateVector
	if qc.OOPK.geoIntersection != nil {
		memUsageBeforeAgg += firstColumnSize * 4 * 2
	}

	// 7. max(memUsageBeforeAgg, sortReduceMemoryUsage)
	memUsage = memUsageBeforeAgg
	if !qc.IsNonAggregationQuery {
		memUsage = int(math.Max(float64(memUsage), float64(estimateSortReduceMemUsage(firstColumnSize))))
	}

	// 8. Dimension vector memory usage (input + output)
	if qc.IsNonAggregationQuery {
		maxRowsPerBatch := maxSizeAfterPreFilter
		if qc.Query.Limit < maxRowsPerBatch {
			maxRowsPerBatch = qc.Query.Limit
		}
		memUsage += maxRowsPerBatch * qc.OOPK.DimRowBytes * 2
	} else {
		if qc.OOPK.UseHashReduction() {
			// For hash reduction, need hash table with int64_t key (8 bytes) and measureBytes value.
			// The capacity is 2 * size.
			memUsage += firstColumnSize * (8 + qc.OOPK.MeasureBytes) * 2
		} else {
			// For sort based reduction, need to allocate space for hash vectors (8bytes each) and
			// dim index vectors (4 bytes each)
			memUsage += firstColumnSize * (4 + 8) * 2
		}
		memUsage += firstColumnSize * qc.OOPK.DimRowBytes * 2
	}

	// 9. Measure vector memory usage (input + output)
	memUsage += firstColumnSize * qc.OOPK.MeasureBytes * 2

	return
}

// memory usage duration expression (filter, dimension, measure) evaluation
func (qc *AQLQueryContext) estimateExpressionEvaluationMemUsage(inputSize int) (memUsage int) {