diff --git a/lib/logstorage/pipe_sort.go b/lib/logstorage/pipe_sort.go
index 5e1a95cc8..4e7995c3e 100644
--- a/lib/logstorage/pipe_sort.go
+++ b/lib/logstorage/pipe_sort.go
@@ -188,17 +188,16 @@ func (shard *pipeSortProcessorShard) writeBlock(br *blockResult) {
 	byColumnsBufLen := len(byColumnsBuf)
 	for _, bf := range byFields {
 		c := br.getColumnByName(bf.name)
-		values := c.getValues(br)
-		values = shard.copyValues(values)
-		u64Values := shard.createUint64Values(values)
-		f64Values := shard.createFloat64Values(values)
-		timestamps := shard.createTimestampsIfNeeded(br.timestamps, c.isTime)
-		byColumnsBuf = append(byColumnsBuf, sortBlockByColumn{
-			values:     values,
-			u64Values:  u64Values,
-			f64Values:  f64Values,
-			timestamps: timestamps,
-		})
+		byColumnsBuf = append(byColumnsBuf, sortBlockByColumn{})
+		bc := &byColumnsBuf[len(byColumnsBuf)-1]
+		if c.isTime {
+			bc.timestamps = shard.copyTimestamps(br.timestamps)
+		} else {
+			values := c.getValues(br)
+			bc.values = shard.copyValues(values)
+			bc.u64Values = shard.createUint64Values(values)
+			bc.f64Values = shard.createFloat64Values(values)
+		}
 	}
 	shard.byColumnsBuf = byColumnsBuf
 	byColumns := byColumnsBuf[byColumnsBufLen:]
@@ -312,11 +311,7 @@ func (shard *pipeSortProcessorShard) createFloat64Values(values []string) []floa
 	return f64ValuesBuf[f64ValuesBufLen:]
 }
 
-func (shard *pipeSortProcessorShard) createTimestampsIfNeeded(timestamps []int64, isTime bool) []int64 {
-	if !isTime {
-		return nil
-	}
-
+func (shard *pipeSortProcessorShard) copyTimestamps(timestamps []int64) []int64 {
 	timestampsBuf := shard.timestampsBuf
 	timestampsBufLen := len(shard.timestampsBuf)
 	timestampsBuf = append(timestampsBuf, timestamps...)
@@ -461,9 +456,12 @@ func (psp *pipeSortProcessor) flush() error {
 }
 
 type pipeSortWriteContext struct {
-	psp       *pipeSortProcessor
-	rcs       []resultColumn
-	br        blockResult
+	psp *pipeSortProcessor
+	rcs []resultColumn
+	br  blockResult
+
+	auxBuf []byte
+
 	valuesLen int
 }
 
@@ -502,11 +500,20 @@ func (wctx *pipeSortWriteContext) writeRow(shard *pipeSortProcessorShard, rowIdx
 	}
 
 	byColumns := b.byColumns
+	auxBuf := wctx.auxBuf
 	for i := range byFields {
-		v := byColumns[i].values[rr.rowIdx]
-		rcs[i].addValue(v)
-		wctx.valuesLen += len(v)
+		bc := &byColumns[i]
+		if len(bc.timestamps) > 0 {
+			auxBuf = marshalTimestampISO8601(auxBuf[:0], bc.timestamps[rr.rowIdx])
+			rcs[i].addValue(bytesutil.ToUnsafeString(auxBuf))
+			wctx.valuesLen += len(auxBuf)
+		} else {
+			v := bc.values[rr.rowIdx]
+			rcs[i].addValue(v)
+			wctx.valuesLen += len(v)
+		}
 	}
+	wctx.auxBuf = auxBuf
 
 	otherColumns := b.otherColumns
 	for i := range otherColumns {
@@ -594,6 +601,14 @@ func sortBlockLess(shardA *pipeSortProcessorShard, rowIdxA uint, shardB *pipeSor
 			}
 			return tA < tB
 		}
+		if len(cA.timestamps) > 0 {
+			// treat timestamps as smaller than other values
+			return true
+		}
+		if len(cB.timestamps) > 0 {
+			// treat timestamps as smaller than other values
+			return false
+		}
 
 		// Try sorting by uint64 values at first
 		uA := cA.u64Values[rrA.rowIdx]