From 32193b6059d9ff11ace65a9b1def85653e22de94 Mon Sep 17 00:00:00 2001
From: Aliaksandr Valialkin <valyala@victoriametrics.com>
Date: Tue, 14 May 2024 01:23:44 +0200
Subject: [PATCH] lib/encoding: optimize UnmarshalVarUint64, UnmarshalVarInt64
 and UnmarshalBytes a bit

Change the return values for these functions - now they return the unmarshaled result plus
the size of the unmarshaled result in bytes, so the caller could re-slice the src for further unmarshaling.

This improves performance of these functions in hot loops of VictoriaLogs a bit.
---
 lib/encoding/encoding.go          |   8 +--
 lib/encoding/int.go               |  60 ++++++++++------
 lib/encoding/int_test.go          |  21 +++---
 lib/encoding/int_timing_test.go   |  16 ++---
 lib/logstorage/block_header.go    | 112 +++++++++++++++---------------
 lib/logstorage/encoding.go        |   9 +--
 lib/logstorage/indexdb.go         |  10 +--
 lib/logstorage/pipe_stats.go      |   8 +--
 lib/logstorage/pipe_uniq.go       |  24 +++----
 lib/logstorage/rows.go            |  16 ++---
 lib/logstorage/stream_tags.go     |  24 +++----
 lib/logstorage/values_encoder.go  |   8 +--
 lib/mergeset/block_header.go      |  16 ++---
 lib/mergeset/metaindex_row.go     |   8 +--
 lib/promutils/labelscompressor.go |   8 ++-
 lib/storage/block.go              |  15 ++--
 lib/storage/block_header.go       |  40 +++++++----
 lib/storage/index_db.go           |  16 ++---
 lib/storage/search.go             |  76 ++++++++++----------
 lib/storage/storage.go            |  11 +--
 lib/streamaggr/streamaggr.go      |  19 ++---
 21 files changed, 282 insertions(+), 243 deletions(-)

diff --git a/lib/encoding/encoding.go b/lib/encoding/encoding.go
index 89168529d..6effdb41c 100644
--- a/lib/encoding/encoding.go
+++ b/lib/encoding/encoding.go
@@ -231,12 +231,12 @@ func unmarshalInt64Array(dst []int64, src []byte, mt MarshalType, firstValue int
 		return dst, nil
 	case MarshalTypeDeltaConst:
 		v := firstValue
-		tail, d, err := UnmarshalVarInt64(src)
-		if err != nil {
+		d, nLen := UnmarshalVarInt64(src)
+		if nLen <= 0 {
 			return nil, fmt.Errorf("cannot unmarshal delta value for delta const: %w", err)
 		}
-		if len(tail) > 0 {
-			return nil, fmt.Errorf("unexpected trailing data after delta const (d=%d): %d bytes", d, len(tail))
+		if nLen < len(src) {
+			return nil, fmt.Errorf("unexpected trailing data after delta const (d=%d): %d bytes", d, len(src)-nLen)
 		}
 		for itemsCount > 0 {
 			dst = append(dst, v)
diff --git a/lib/encoding/int.go b/lib/encoding/int.go
index aef274a8e..a0cd4a715 100644
--- a/lib/encoding/int.go
+++ b/lib/encoding/int.go
@@ -167,16 +167,15 @@ func marshalVarInt64sSlow(dst []byte, vs []int64) []byte {
 	return dst
 }
 
-// UnmarshalVarInt64 returns unmarshaled int64 from src and returns the remaining tail from src.
-func UnmarshalVarInt64(src []byte) ([]byte, int64, error) {
+// UnmarshalVarInt64 returns unmarshaled int64 from src and its size in bytes.
+//
+// It returns 0 or negative value if it cannot unmarshal int64 from src.
+func UnmarshalVarInt64(src []byte) (int64, int) {
 	// TODO substitute binary.Uvarint with binary.Varint when benchmark results will show it is faster.
 	// It is slower on amd64/linux Go1.22.
-	u64, offset := binary.Uvarint(src)
-	if offset <= 0 {
-		return src, 0, fmt.Errorf("cannot unmarshal varint")
-	}
+	u64, nSize := binary.Uvarint(src)
 	i64 := int64(int64(u64>>1) ^ (int64(u64<<63) >> 63))
-	return src[offset:], i64, nil
+	return i64, nSize
 }
 
 // UnmarshalVarInt64s unmarshals len(dst) int64 values from src to dst and returns the remaining tail from src.
@@ -363,13 +362,27 @@ func marshalVarUint64sSlow(dst []byte, us []uint64) []byte {
 	return dst
 }
 
-// UnmarshalVarUint64 returns unmarshaled uint64 from src and returns the remaining tail from src.
-func UnmarshalVarUint64(src []byte) ([]byte, uint64, error) {
-	u64, offset := binary.Uvarint(src)
-	if offset <= 0 {
-		return src, 0, fmt.Errorf("cannot read varuint")
+// UnmarshalVarUint64 returns unmarshaled uint64 from src and its size in bytes.
+//
+// It returns 0 or negative value if it cannot unmarshal uint64 from src.
+func UnmarshalVarUint64(src []byte) (uint64, int) {
+	if len(src) == 0 {
+		return 0, 0
 	}
-	return src[offset:], u64, nil
+	if src[0] < 0x80 {
+		// Fast path for a single byte
+		return uint64(src[0]), 1
+	}
+	if len(src) == 1 {
+		return 0, 0
+	}
+	if src[1] < 0x80 {
+		// Fast path for two bytes
+		return uint64(src[0]&0x7f) | uint64(src[1])<<7, 2
+	}
+
+	// Slow path for other number of bytes
+	return binary.Uvarint(src)
 }
 
 // UnmarshalVarUint64s unmarshals len(dst) uint64 values from src to dst and returns the remaining tail from src.
@@ -496,17 +509,20 @@ func MarshalBytes(dst, b []byte) []byte {
 	return dst
 }
 
-// UnmarshalBytes returns unmarshaled bytes from src.
-func UnmarshalBytes(src []byte) ([]byte, []byte, error) {
-	tail, n, err := UnmarshalVarUint64(src)
-	if err != nil {
-		return nil, nil, fmt.Errorf("cannot unmarshal string size: %w", err)
+// UnmarshalBytes returns unmarshaled bytes from src and the size of the unmarshaled bytes.
+//
+// It returns 0 or negative value if it is impossible to unmarshal bytes from src.
+func UnmarshalBytes(src []byte) ([]byte, int) {
+	n, nSize := UnmarshalVarUint64(src)
+	if nSize <= 0 {
+		return nil, 0
 	}
-	src = tail
-	if uint64(len(src)) < n {
-		return nil, nil, fmt.Errorf("src is too short for reading string with size %d; len(src)=%d", n, len(src))
+	if uint64(nSize)+n > uint64(len(src)) {
+		return nil, 0
 	}
-	return src[n:], src[:n], nil
+	start := nSize
+	nSize += int(n)
+	return src[start:nSize], nSize
 }
 
 // GetInt64s returns an int64 slice with the given size.
diff --git a/lib/encoding/int_test.go b/lib/encoding/int_test.go
index d38bbe81d..f8b75c94c 100644
--- a/lib/encoding/int_test.go
+++ b/lib/encoding/int_test.go
@@ -224,10 +224,11 @@ func testMarshalUnmarshalVarInt64(t *testing.T, v int64) {
 	t.Helper()
 
 	b := MarshalVarInt64(nil, v)
-	tail, vNew, err := UnmarshalVarInt64(b)
-	if err != nil {
-		t.Fatalf("unexpected error when unmarshaling v=%d from b=%x: %s", v, b, err)
+	vNew, nSize := UnmarshalVarInt64(b)
+	if nSize <= 0 {
+		t.Fatalf("unexpected error when unmarshaling v=%d from b=%x", v, b)
 	}
+	tail := b[nSize:]
 	if vNew != v {
 		t.Fatalf("unexpected vNew from b=%x; got %d; expecting %d", b, vNew, v)
 	}
@@ -272,10 +273,11 @@ func testMarshalUnmarshalVarUint64(t *testing.T, u uint64) {
 	t.Helper()
 
 	b := MarshalVarUint64(nil, u)
-	tail, uNew, err := UnmarshalVarUint64(b)
-	if err != nil {
-		t.Fatalf("unexpected error when unmarshaling u=%d from b=%x: %s", u, b, err)
+	uNew, nSize := UnmarshalVarUint64(b)
+	if nSize <= 0 {
+		t.Fatalf("unexpected error when unmarshaling u=%d from b=%x", u, b)
 	}
+	tail := b[nSize:]
 	if uNew != u {
 		t.Fatalf("unexpected uNew from b=%x; got %d; expecting %d", b, uNew, u)
 	}
@@ -310,10 +312,11 @@ func testMarshalUnmarshalBytes(t *testing.T, s string) {
 	t.Helper()
 
 	b := MarshalBytes(nil, []byte(s))
-	tail, bNew, err := UnmarshalBytes(b)
-	if err != nil {
-		t.Fatalf("unexpected error when unmarshaling s=%q from b=%x: %s", s, b, err)
+	bNew, nSize := UnmarshalBytes(b)
+	if nSize <= 0 {
+		t.Fatalf("unexpected error when unmarshaling s=%q from b=%x", s, b)
 	}
+	tail := b[nSize:]
 	if string(bNew) != s {
 		t.Fatalf("unexpected sNew from b=%x; got %q; expecting %q", b, bNew, s)
 	}
diff --git a/lib/encoding/int_timing_test.go b/lib/encoding/int_timing_test.go
index 481316e2e..602cf8486 100644
--- a/lib/encoding/int_timing_test.go
+++ b/lib/encoding/int_timing_test.go
@@ -173,12 +173,12 @@ func benchmarkUnmarshalVarUint64(b *testing.B, maxValue uint64) {
 		for pb.Next() {
 			src := data
 			for len(src) > 0 {
-				tail, n, err := UnmarshalVarUint64(src)
-				if err != nil {
-					panic(fmt.Errorf("unexpected error: %w", err))
+				n, nSize := UnmarshalVarUint64(src)
+				if nSize <= 0 {
+					panic(fmt.Errorf("unexpected error"))
 				}
+				src = src[nSize:]
 				sink += n
-				src = tail
 			}
 		}
 		Sink.Add(sink)
@@ -265,12 +265,12 @@ func benchmarkUnmarshalVarInt64(b *testing.B, maxValue int64) {
 		for pb.Next() {
 			src := data
 			for len(src) > 0 {
-				tail, n, err := UnmarshalVarInt64(src)
-				if err != nil {
-					panic(fmt.Errorf("unexpected error: %w", err))
+				n, nSize := UnmarshalVarInt64(src)
+				if nSize <= 0 {
+					panic(fmt.Errorf("unexpected error"))
 				}
+				src = src[nSize:]
 				sink += uint64(n)
-				src = tail
 			}
 		}
 		Sink.Add(sink)
diff --git a/lib/logstorage/block_header.go b/lib/logstorage/block_header.go
index edd28fe9f..578cae535 100644
--- a/lib/logstorage/block_header.go
+++ b/lib/logstorage/block_header.go
@@ -85,23 +85,23 @@ func (bh *blockHeader) unmarshal(src []byte) ([]byte, error) {
 	src = tail
 
 	// unmarshal bh.uncompressedSizeBytes
-	tail, n, err := encoding.UnmarshalVarUint64(src)
-	if err != nil {
-		return srcOrig, fmt.Errorf("cannot unmarshal uncompressedSizeBytes: %w", err)
+	n, nSize := encoding.UnmarshalVarUint64(src)
+	if nSize <= 0 {
+		return srcOrig, fmt.Errorf("cannot unmarshal uncompressedSizeBytes")
 	}
+	src = src[nSize:]
 	bh.uncompressedSizeBytes = n
-	src = tail
 
 	// unmarshal bh.rowsCount
-	tail, n, err = encoding.UnmarshalVarUint64(src)
-	if err != nil {
-		return srcOrig, fmt.Errorf("cannot unmarshal rowsCount: %w", err)
+	n, nSize = encoding.UnmarshalVarUint64(src)
+	if nSize <= 0 {
+		return srcOrig, fmt.Errorf("cannot unmarshal rowsCount")
 	}
+	src = src[nSize:]
 	if n > maxRowsPerBlock {
 		return srcOrig, fmt.Errorf("too big value for rowsCount: %d; mustn't exceed %d", n, maxRowsPerBlock)
 	}
 	bh.rowsCount = n
-	src = tail
 
 	// unmarshal bh.timestampsHeader
 	tail, err = bh.timestampsHeader.unmarshal(src)
@@ -111,23 +111,23 @@ func (bh *blockHeader) unmarshal(src []byte) ([]byte, error) {
 	src = tail
 
 	// unmarshal columnsHeaderOffset
-	tail, n, err = encoding.UnmarshalVarUint64(src)
-	if err != nil {
-		return srcOrig, fmt.Errorf("cannot unmarshal columnsHeaderOffset: %w", err)
+	n, nSize = encoding.UnmarshalVarUint64(src)
+	if nSize <= 0 {
+		return srcOrig, fmt.Errorf("cannot unmarshal columnsHeaderOffset")
 	}
+	src = src[nSize:]
 	bh.columnsHeaderOffset = n
-	src = tail
 
 	// unmarshal columnsHeaderSize
-	tail, n, err = encoding.UnmarshalVarUint64(src)
-	if err != nil {
-		return srcOrig, fmt.Errorf("cannot unmarshal columnsHeaderSize: %w", err)
+	n, nSize = encoding.UnmarshalVarUint64(src)
+	if nSize <= 0 {
+		return srcOrig, fmt.Errorf("cannot unmarshal columnsHeaderSize")
 	}
+	src = src[nSize:]
 	if n > maxColumnsHeaderSize {
 		return srcOrig, fmt.Errorf("too big value for columnsHeaderSize: %d; mustn't exceed %d", n, maxColumnsHeaderSize)
 	}
 	bh.columnsHeaderSize = n
-	src = tail
 
 	return src, nil
 }
@@ -296,17 +296,18 @@ func (csh *columnsHeader) unmarshal(a *arena, src []byte) error {
 	csh.reset()
 
 	// unmarshal columnHeaders
-	tail, n, err := encoding.UnmarshalVarUint64(src)
-	if err != nil {
-		return fmt.Errorf("cannot unmarshal columnHeaders len: %w", err)
+	n, nSize := encoding.UnmarshalVarUint64(src)
+	if nSize <= 0 {
+		return fmt.Errorf("cannot unmarshal columnHeaders len")
 	}
+	src = src[nSize:]
 	if n > maxColumnsPerBlock {
 		return fmt.Errorf("too many column headers: %d; mustn't exceed %d", n, maxColumnsPerBlock)
 	}
-	src = tail
+
 	chs := csh.resizeColumnHeaders(int(n))
 	for i := range chs {
-		tail, err = chs[i].unmarshal(a, src)
+		tail, err := chs[i].unmarshal(a, src)
 		if err != nil {
 			return fmt.Errorf("cannot unmarshal columnHeader %d out of %d columnHeaders: %w", i, len(chs), err)
 		}
@@ -315,17 +316,18 @@ func (csh *columnsHeader) unmarshal(a *arena, src []byte) error {
 	csh.columnHeaders = chs
 
 	// unmarshal constColumns
-	tail, n, err = encoding.UnmarshalVarUint64(src)
-	if err != nil {
-		return fmt.Errorf("cannot unmarshal constColumns len: %w", err)
+	n, nSize = encoding.UnmarshalVarUint64(src)
+	if nSize <= 0 {
+		return fmt.Errorf("cannot unmarshal constColumns len")
 	}
+	src = src[nSize:]
 	if n+uint64(len(csh.columnHeaders)) > maxColumnsPerBlock {
 		return fmt.Errorf("too many columns: %d; mustn't exceed %d", n+uint64(len(csh.columnHeaders)), maxColumnsPerBlock)
 	}
-	src = tail
+
 	ccs := csh.resizeConstColumns(int(n))
 	for i := range ccs {
-		tail, err = ccs[i].unmarshal(a, src)
+		tail, err := ccs[i].unmarshal(a, src)
 		if err != nil {
 			return fmt.Errorf("cannot unmarshal constColumn %d out of %d columns: %w", i, len(ccs), err)
 		}
@@ -504,12 +506,12 @@ func (ch *columnHeader) unmarshal(a *arena, src []byte) ([]byte, error) {
 	srcOrig := src
 
 	// Unmarshal column name
-	tail, data, err := encoding.UnmarshalBytes(src)
-	if err != nil {
-		return srcOrig, fmt.Errorf("cannot unmarshal column name: %w", err)
+	data, nSize := encoding.UnmarshalBytes(src)
+	if nSize <= 0 {
+		return srcOrig, fmt.Errorf("cannot unmarshal column name")
 	}
+	src = src[nSize:]
 	ch.name = a.copyBytesToString(data)
-	src = tail
 
 	// Unmarshal value type
 	if len(src) < 1 {
@@ -521,13 +523,13 @@ func (ch *columnHeader) unmarshal(a *arena, src []byte) ([]byte, error) {
 	// Unmarshal the rest of data depending on valueType
 	switch ch.valueType {
 	case valueTypeString:
-		tail, err = ch.unmarshalValuesAndBloomFilters(src)
+		tail, err := ch.unmarshalValuesAndBloomFilters(src)
 		if err != nil {
 			return srcOrig, fmt.Errorf("cannot unmarshal values and bloom filters at valueTypeString for column %q: %w", ch.name, err)
 		}
 		src = tail
 	case valueTypeDict:
-		tail, err = ch.valuesDict.unmarshal(a, src)
+		tail, err := ch.valuesDict.unmarshal(a, src)
 		if err != nil {
 			return srcOrig, fmt.Errorf("cannot unmarshal dict at valueTypeDict for column %q: %w", ch.name, err)
 		}
@@ -546,7 +548,7 @@ func (ch *columnHeader) unmarshal(a *arena, src []byte) ([]byte, error) {
 		ch.maxValue = uint64(src[1])
 		src = src[2:]
 
-		tail, err = ch.unmarshalValuesAndBloomFilters(src)
+		tail, err := ch.unmarshalValuesAndBloomFilters(src)
 		if err != nil {
 			return srcOrig, fmt.Errorf("cannot unmarshal values and bloom filters at valueTypeUint8 for column %q: %w", ch.name, err)
 		}
@@ -559,7 +561,7 @@ func (ch *columnHeader) unmarshal(a *arena, src []byte) ([]byte, error) {
 		ch.maxValue = uint64(encoding.UnmarshalUint16(src[2:]))
 		src = src[4:]
 
-		tail, err = ch.unmarshalValuesAndBloomFilters(src)
+		tail, err := ch.unmarshalValuesAndBloomFilters(src)
 		if err != nil {
 			return srcOrig, fmt.Errorf("cannot unmarshal values and bloom filters at valueTypeUint16 for column %q: %w", ch.name, err)
 		}
@@ -572,7 +574,7 @@ func (ch *columnHeader) unmarshal(a *arena, src []byte) ([]byte, error) {
 		ch.maxValue = uint64(encoding.UnmarshalUint32(src[4:]))
 		src = src[8:]
 
-		tail, err = ch.unmarshalValuesAndBloomFilters(src)
+		tail, err := ch.unmarshalValuesAndBloomFilters(src)
 		if err != nil {
 			return srcOrig, fmt.Errorf("cannot unmarshal values and bloom filters at valueTypeUint32 for column %q: %w", ch.name, err)
 		}
@@ -585,7 +587,7 @@ func (ch *columnHeader) unmarshal(a *arena, src []byte) ([]byte, error) {
 		ch.maxValue = encoding.UnmarshalUint64(src[8:])
 		src = src[16:]
 
-		tail, err = ch.unmarshalValuesAndBloomFilters(src)
+		tail, err := ch.unmarshalValuesAndBloomFilters(src)
 		if err != nil {
 			return srcOrig, fmt.Errorf("cannot unmarshal values and bloom filters at valueTypeUint64 for column %q: %w", ch.name, err)
 		}
@@ -599,7 +601,7 @@ func (ch *columnHeader) unmarshal(a *arena, src []byte) ([]byte, error) {
 		ch.maxValue = encoding.UnmarshalUint64(src[8:])
 		src = src[16:]
 
-		tail, err = ch.unmarshalValuesAndBloomFilters(src)
+		tail, err := ch.unmarshalValuesAndBloomFilters(src)
 		if err != nil {
 			return srcOrig, fmt.Errorf("cannot unmarshal values and bloom filters at valueTypeFloat64 for column %q: %w", ch.name, err)
 		}
@@ -612,7 +614,7 @@ func (ch *columnHeader) unmarshal(a *arena, src []byte) ([]byte, error) {
 		ch.maxValue = uint64(encoding.UnmarshalUint32(src[4:]))
 		src = src[8:]
 
-		tail, err = ch.unmarshalValuesAndBloomFilters(src)
+		tail, err := ch.unmarshalValuesAndBloomFilters(src)
 		if err != nil {
 			return srcOrig, fmt.Errorf("cannot unmarshal values and bloom filters at valueTypeIPv4 for column %q: %w", ch.name, err)
 		}
@@ -626,7 +628,7 @@ func (ch *columnHeader) unmarshal(a *arena, src []byte) ([]byte, error) {
 		ch.maxValue = encoding.UnmarshalUint64(src[8:])
 		src = src[16:]
 
-		tail, err = ch.unmarshalValuesAndBloomFilters(src)
+		tail, err := ch.unmarshalValuesAndBloomFilters(src)
 		if err != nil {
 			return srcOrig, fmt.Errorf("cannot unmarshal values and bloom filters at valueTypeTimestampISO8601 for column %q: %w", ch.name, err)
 		}
@@ -659,22 +661,22 @@ func (ch *columnHeader) unmarshalValuesAndBloomFilters(src []byte) ([]byte, erro
 func (ch *columnHeader) unmarshalValues(src []byte) ([]byte, error) {
 	srcOrig := src
 
-	tail, n, err := encoding.UnmarshalVarUint64(src)
-	if err != nil {
-		return srcOrig, fmt.Errorf("cannot unmarshal valuesOffset: %w", err)
+	n, nSize := encoding.UnmarshalVarUint64(src)
+	if nSize <= 0 {
+		return srcOrig, fmt.Errorf("cannot unmarshal valuesOffset")
 	}
+	src = src[nSize:]
 	ch.valuesOffset = n
-	src = tail
 
-	tail, n, err = encoding.UnmarshalVarUint64(src)
-	if err != nil {
-		return srcOrig, fmt.Errorf("cannot unmarshal valuesSize: %w", err)
+	n, nSize = encoding.UnmarshalVarUint64(src)
+	if nSize <= 0 {
+		return srcOrig, fmt.Errorf("cannot unmarshal valuesSize")
 	}
+	src = src[nSize:]
 	if n > maxValuesBlockSize {
 		return srcOrig, fmt.Errorf("too big valuesSize: %d bytes; mustn't exceed %d bytes", n, maxValuesBlockSize)
 	}
 	ch.valuesSize = n
-	src = tail
 
 	return src, nil
 }
@@ -682,22 +684,22 @@ func (ch *columnHeader) unmarshalValues(src []byte) ([]byte, error) {
 func (ch *columnHeader) unmarshalBloomFilters(src []byte) ([]byte, error) {
 	srcOrig := src
 
-	tail, n, err := encoding.UnmarshalVarUint64(src)
-	if err != nil {
-		return srcOrig, fmt.Errorf("cannot unmarshal bloomFilterOffset: %w", err)
+	n, nSize := encoding.UnmarshalVarUint64(src)
+	if nSize <= 0 {
+		return srcOrig, fmt.Errorf("cannot unmarshal bloomFilterOffset")
 	}
+	src = src[nSize:]
 	ch.bloomFilterOffset = n
-	src = tail
 
-	tail, n, err = encoding.UnmarshalVarUint64(src)
-	if err != nil {
-		return srcOrig, fmt.Errorf("cannot unmarshal bloomFilterSize: %w", err)
+	n, nSize = encoding.UnmarshalVarUint64(src)
+	if nSize <= 0 {
+		return srcOrig, fmt.Errorf("cannot unmarshal bloomFilterSize")
 	}
+	src = src[nSize:]
 	if n > maxBloomFilterBlockSize {
 		return srcOrig, fmt.Errorf("too big bloomFilterSize: %d bytes; mustn't exceed %d bytes", n, maxBloomFilterBlockSize)
 	}
 	ch.bloomFilterSize = n
-	src = tail
 
 	return src, nil
 }
diff --git a/lib/logstorage/encoding.go b/lib/logstorage/encoding.go
index ccce895f7..083519957 100644
--- a/lib/logstorage/encoding.go
+++ b/lib/logstorage/encoding.go
@@ -279,11 +279,11 @@ func unmarshalBytesBlock(dst, src []byte) ([]byte, []byte, error) {
 		// Compressed block
 
 		// Read block length
-		tail, blockLen, err := encoding.UnmarshalVarUint64(src)
-		if err != nil {
-			return dst, src, fmt.Errorf("cannot unmarshal compressed block size: %w", err)
+		blockLen, nSize := encoding.UnmarshalVarUint64(src)
+		if nSize <= 0 {
+			return dst, src, fmt.Errorf("cannot unmarshal compressed block size")
 		}
-		src = tail
+		src = src[nSize:]
 		if uint64(len(src)) < blockLen {
 			return dst, src, fmt.Errorf("cannot read compressed block with the size %d bytes from %d bytes", blockLen, len(src))
 		}
@@ -292,6 +292,7 @@ func unmarshalBytesBlock(dst, src []byte) ([]byte, []byte, error) {
 
 		// Decompress the block
 		bb := bbPool.Get()
+		var err error
 		bb.B, err = encoding.DecompressZSTD(bb.B[:0], compressedBlock)
 		if err != nil {
 			return dst, src, fmt.Errorf("cannot decompress block: %w", err)
diff --git a/lib/logstorage/indexdb.go b/lib/logstorage/indexdb.go
index e98afb244..dba66b3a1 100644
--- a/lib/logstorage/indexdb.go
+++ b/lib/logstorage/indexdb.go
@@ -507,14 +507,14 @@ func (idb *indexdb) loadStreamIDsFromCache(tenantIDs []TenantID, sf *StreamFilte
 		return nil, false
 	}
 	// Cache hit - unpack streamIDs from data.
-	tail, n, err := encoding.UnmarshalVarUint64(data)
-	if err != nil {
-		logger.Panicf("BUG: unexpected error when unmarshaling the number of streamIDs from cache: %s", err)
+	n, nSize := encoding.UnmarshalVarUint64(data)
+	if nSize <= 0 {
+		logger.Panicf("BUG: unexpected error when unmarshaling the number of streamIDs from cache")
 	}
-	src := tail
+	src := data[nSize:]
 	streamIDs := make([]streamID, n)
 	for i := uint64(0); i < n; i++ {
-		tail, err = streamIDs[i].unmarshal(src)
+		tail, err := streamIDs[i].unmarshal(src)
 		if err != nil {
 			logger.Panicf("BUG: unexpected error when unmarshaling streamID #%d: %s", i, err)
 		}
diff --git a/lib/logstorage/pipe_stats.go b/lib/logstorage/pipe_stats.go
index 88a0bf8d3..3a9d8980b 100644
--- a/lib/logstorage/pipe_stats.go
+++ b/lib/logstorage/pipe_stats.go
@@ -398,12 +398,12 @@ func (psp *pipeStatsProcessor) flush() error {
 		values = values[:0]
 		keyBuf := bytesutil.ToUnsafeBytes(key)
 		for len(keyBuf) > 0 {
-			tail, v, err := encoding.UnmarshalBytes(keyBuf)
-			if err != nil {
-				logger.Panicf("BUG: cannot unmarshal value from keyBuf=%q: %w", keyBuf, err)
+			v, nSize := encoding.UnmarshalBytes(keyBuf)
+			if nSize <= 0 {
+				logger.Panicf("BUG: cannot unmarshal value from keyBuf=%q", keyBuf)
 			}
+			keyBuf = keyBuf[nSize:]
 			values = append(values, bytesutil.ToUnsafeString(v))
-			keyBuf = tail
 		}
 		if len(values) != len(byFields) {
 			logger.Panicf("BUG: unexpected number of values decoded from keyBuf; got %d; want %d", len(values), len(byFields))
diff --git a/lib/logstorage/pipe_uniq.go b/lib/logstorage/pipe_uniq.go
index 6c171b931..6cdd46fc7 100644
--- a/lib/logstorage/pipe_uniq.go
+++ b/lib/logstorage/pipe_uniq.go
@@ -238,17 +238,17 @@ func (pup *pipeUniqProcessor) flush() error {
 			rowFields = rowFields[:0]
 			keyBuf := bytesutil.ToUnsafeBytes(k)
 			for len(keyBuf) > 0 {
-				tail, name, err := encoding.UnmarshalBytes(keyBuf)
-				if err != nil {
-					logger.Panicf("BUG: cannot unmarshal field name: %s", err)
+				name, nSize := encoding.UnmarshalBytes(keyBuf)
+				if nSize <= 0 {
+					logger.Panicf("BUG: cannot unmarshal field name")
 				}
-				keyBuf = tail
+				keyBuf = keyBuf[nSize:]
 
-				tail, value, err := encoding.UnmarshalBytes(keyBuf)
-				if err != nil {
-					logger.Panicf("BUG: cannot unmarshal field value: %s", err)
+				value, nSize := encoding.UnmarshalBytes(keyBuf)
+				if nSize <= 0 {
+					logger.Panicf("BUG: cannot unmarshal field value")
 				}
-				keyBuf = tail
+				keyBuf = keyBuf[nSize:]
 
 				rowFields = append(rowFields, Field{
 					Name:  bytesutil.ToUnsafeString(name),
@@ -269,11 +269,11 @@ func (pup *pipeUniqProcessor) flush() error {
 			keyBuf := bytesutil.ToUnsafeBytes(k)
 			fieldIdx := 0
 			for len(keyBuf) > 0 {
-				tail, value, err := encoding.UnmarshalBytes(keyBuf)
-				if err != nil {
-					logger.Panicf("BUG: cannot unmarshal field value: %s", err)
+				value, nSize := encoding.UnmarshalBytes(keyBuf)
+				if nSize <= 0 {
+					logger.Panicf("BUG: cannot unmarshal field value")
 				}
-				keyBuf = tail
+				keyBuf = keyBuf[nSize:]
 
 				rowFields = append(rowFields, Field{
 					Name:  byFields[fieldIdx],
diff --git a/lib/logstorage/rows.go b/lib/logstorage/rows.go
index 62ab3c53f..fe7c268fd 100644
--- a/lib/logstorage/rows.go
+++ b/lib/logstorage/rows.go
@@ -38,20 +38,20 @@ func (f *Field) unmarshal(a *arena, src []byte) ([]byte, error) {
 	srcOrig := src
 
 	// Unmarshal field name
-	tail, b, err := encoding.UnmarshalBytes(src)
-	if err != nil {
-		return srcOrig, fmt.Errorf("cannot unmarshal field name: %w", err)
+	b, nSize := encoding.UnmarshalBytes(src)
+	if nSize <= 0 {
+		return srcOrig, fmt.Errorf("cannot unmarshal field name")
 	}
+	src = src[nSize:]
 	f.Name = a.copyBytesToString(b)
-	src = tail
 
 	// Unmarshal field value
-	tail, b, err = encoding.UnmarshalBytes(src)
-	if err != nil {
-		return srcOrig, fmt.Errorf("cannot unmarshal field value: %w", err)
+	b, nSize = encoding.UnmarshalBytes(src)
+	if nSize <= 0 {
+		return srcOrig, fmt.Errorf("cannot unmarshal field value")
 	}
+	src = src[nSize:]
 	f.Value = a.copyBytesToString(b)
-	src = tail
 
 	return src, nil
 }
diff --git a/lib/logstorage/stream_tags.go b/lib/logstorage/stream_tags.go
index b83567cc3..2e946bab6 100644
--- a/lib/logstorage/stream_tags.go
+++ b/lib/logstorage/stream_tags.go
@@ -119,23 +119,23 @@ func (st *StreamTags) UnmarshalCanonical(src []byte) ([]byte, error) {
 
 	srcOrig := src
 
-	tail, n, err := encoding.UnmarshalVarUint64(src)
-	if err != nil {
-		return srcOrig, fmt.Errorf("cannot unmarshal tags len: %w", err)
+	n, nSize := encoding.UnmarshalVarUint64(src)
+	if nSize <= 0 {
+		return srcOrig, fmt.Errorf("cannot unmarshal tags len")
 	}
-	src = tail
+	src = src[nSize:]
 	for i := uint64(0); i < n; i++ {
-		tail, name, err := encoding.UnmarshalBytes(src)
-		if err != nil {
-			return srcOrig, fmt.Errorf("cannot unmarshal tag name: %w", err)
+		name, nSize := encoding.UnmarshalBytes(src)
+		if nSize <= 0 {
+			return srcOrig, fmt.Errorf("cannot unmarshal tag name")
 		}
-		src = tail
+		src = src[nSize:]
 
-		tail, value, err := encoding.UnmarshalBytes(src)
-		if err != nil {
-			return srcOrig, fmt.Errorf("cannot unmarshal tag value: %w", err)
+		value, nSize := encoding.UnmarshalBytes(src)
+		if nSize <= 0 {
+			return srcOrig, fmt.Errorf("cannot unmarshal tag value")
 		}
-		src = tail
+		src = src[nSize:]
 
 		sName := bytesutil.ToUnsafeString(name)
 		sValue := bytesutil.ToUnsafeString(value)
diff --git a/lib/logstorage/values_encoder.go b/lib/logstorage/values_encoder.go
index 131721b70..9b7da6069 100644
--- a/lib/logstorage/values_encoder.go
+++ b/lib/logstorage/values_encoder.go
@@ -1137,11 +1137,11 @@ func (vd *valuesDict) unmarshal(a *arena, src []byte) ([]byte, error) {
 	dictLen := int(src[0])
 	src = src[1:]
 	for i := 0; i < dictLen; i++ {
-		tail, data, err := encoding.UnmarshalBytes(src)
-		if err != nil {
-			return srcOrig, fmt.Errorf("cannot umarshal value %d out of %d from dict: %w", i, dictLen, err)
+		data, nSize := encoding.UnmarshalBytes(src)
+		if nSize <= 0 {
+			return srcOrig, fmt.Errorf("cannot umarshal value %d out of %d from dict", i, dictLen)
 		}
-		src = tail
+		src = src[nSize:]
 
 		v := a.copyBytesToString(data)
 		vd.values = append(vd.values, v)
diff --git a/lib/mergeset/block_header.go b/lib/mergeset/block_header.go
index 817fee7e6..a0fb1af2c 100644
--- a/lib/mergeset/block_header.go
+++ b/lib/mergeset/block_header.go
@@ -77,20 +77,20 @@ func (bh *blockHeader) Marshal(dst []byte) []byte {
 func (bh *blockHeader) UnmarshalNoCopy(src []byte) ([]byte, error) {
 	bh.noCopy = true
 	// Unmarshal commonPrefix
-	tail, cp, err := encoding.UnmarshalBytes(src)
-	if err != nil {
-		return tail, fmt.Errorf("cannot unmarshal commonPrefix: %w", err)
+	cp, nSize := encoding.UnmarshalBytes(src)
+	if nSize <= 0 {
+		return src, fmt.Errorf("cannot unmarshal commonPrefix")
 	}
+	src = src[nSize:]
 	bh.commonPrefix = cp[:len(cp):len(cp)]
-	src = tail
 
 	// Unmarshal firstItem
-	tail, fi, err := encoding.UnmarshalBytes(src)
-	if err != nil {
-		return tail, fmt.Errorf("cannot unmarshal firstItem: %w", err)
+	fi, nSize := encoding.UnmarshalBytes(src)
+	if nSize <= 0 {
+		return src, fmt.Errorf("cannot unmarshal firstItem")
 	}
+	src = src[nSize:]
 	bh.firstItem = fi[:len(fi):len(fi)]
-	src = tail
 
 	// Unmarshal marshalType
 	if len(src) == 0 {
diff --git a/lib/mergeset/metaindex_row.go b/lib/mergeset/metaindex_row.go
index e80ba19a4..6e3e02ad5 100644
--- a/lib/mergeset/metaindex_row.go
+++ b/lib/mergeset/metaindex_row.go
@@ -41,12 +41,12 @@ func (mr *metaindexRow) Marshal(dst []byte) []byte {
 
 func (mr *metaindexRow) Unmarshal(src []byte) ([]byte, error) {
 	// Unmarshal firstItem
-	tail, fi, err := encoding.UnmarshalBytes(src)
-	if err != nil {
-		return tail, fmt.Errorf("cannot unmarshal firstItem: %w", err)
+	fi, nSize := encoding.UnmarshalBytes(src)
+	if nSize <= 0 {
+		return src, fmt.Errorf("cannot unmarshal firstItem")
 	}
+	src = src[nSize:]
 	mr.firstItem = append(mr.firstItem[:0], fi...)
-	src = tail
 
 	// Unmarshal blockHeadersCount
 	if len(src) < 4 {
diff --git a/lib/promutils/labelscompressor.go b/lib/promutils/labelscompressor.go
index a135d8e92..391b8f3c5 100644
--- a/lib/promutils/labelscompressor.go
+++ b/lib/promutils/labelscompressor.go
@@ -91,10 +91,11 @@ func cloneLabel(label prompbmarshal.Label) prompbmarshal.Label {
 //
 // It is safe calling Decompress from concurrent goroutines.
 func (lc *LabelsCompressor) Decompress(dst []prompbmarshal.Label, src []byte) []prompbmarshal.Label {
-	tail, labelsLen, err := encoding.UnmarshalVarUint64(src)
-	if err != nil {
-		logger.Panicf("BUG: cannot unmarshal labels length: %s", err)
+	labelsLen, nSize := encoding.UnmarshalVarUint64(src)
+	if nSize <= 0 {
+		logger.Panicf("BUG: cannot unmarshal labels length from uvarint")
 	}
+	tail := src[nSize:]
 	if labelsLen == 0 {
 		// fast path - nothing to decode
 		if len(tail) > 0 {
@@ -104,6 +105,7 @@ func (lc *LabelsCompressor) Decompress(dst []prompbmarshal.Label, src []byte) []
 	}
 
 	a := encoding.GetUint64s(int(labelsLen))
+	var err error
 	tail, err = encoding.UnmarshalVarUint64s(a.A, tail)
 	if err != nil {
 		logger.Panicf("BUG: cannot unmarshal label indexes: %s", err)
diff --git a/lib/storage/block.go b/lib/storage/block.go
index 43635f651..0aa4e0616 100644
--- a/lib/storage/block.go
+++ b/lib/storage/block.go
@@ -369,15 +369,18 @@ func (b *Block) UnmarshalPortable(src []byte) ([]byte, error) {
 	if err != nil {
 		return src, err
 	}
-	src, timestampsData, err := encoding.UnmarshalBytes(src)
-	if err != nil {
-		return src, fmt.Errorf("cannot read timestampsData: %w", err)
+	timestampsData, nSize := encoding.UnmarshalBytes(src)
+	if nSize <= 0 {
+		return src, fmt.Errorf("cannot read timestampsData")
 	}
+	src = src[nSize:]
 	b.timestampsData = append(b.timestampsData[:0], timestampsData...)
-	src, valuesData, err := encoding.UnmarshalBytes(src)
-	if err != nil {
-		return src, fmt.Errorf("cannot read valuesData: %w", err)
+
+	valuesData, nSize := encoding.UnmarshalBytes(src)
+	if nSize <= 0 {
+		return src, fmt.Errorf("cannot read valuesData")
 	}
+	src = src[nSize:]
 	b.valuesData = append(b.valuesData[:0], valuesData...)
 
 	if err := b.bh.validate(); err != nil {
diff --git a/lib/storage/block_header.go b/lib/storage/block_header.go
index f7689f5f1..293411464 100644
--- a/lib/storage/block_header.go
+++ b/lib/storage/block_header.go
@@ -167,33 +167,42 @@ func (bh *blockHeader) marshalPortable(dst []byte) []byte {
 }
 
 func (bh *blockHeader) unmarshalPortable(src []byte) ([]byte, error) {
-	src, minTimestamp, err := encoding.UnmarshalVarInt64(src)
-	if err != nil {
-		return src, fmt.Errorf("cannot unmarshal firstTimestamp: %w", err)
+	minTimestamp, nSize := encoding.UnmarshalVarInt64(src)
+	if nSize <= 0 {
+		return src, fmt.Errorf("cannot unmarshal firstTimestamp from varint")
 	}
+	src = src[nSize:]
 	bh.MinTimestamp = minTimestamp
-	src, maxTimestamp, err := encoding.UnmarshalVarInt64(src)
-	if err != nil {
-		return src, fmt.Errorf("cannot unmarshal firstTimestamp: %w", err)
+
+	maxTimestamp, nSize := encoding.UnmarshalVarInt64(src)
+	if nSize <= 0 {
+		return src, fmt.Errorf("cannot unmarshal firstTimestamp rom varint")
 	}
+	src = src[nSize:]
 	bh.MaxTimestamp = maxTimestamp
-	src, firstValue, err := encoding.UnmarshalVarInt64(src)
-	if err != nil {
-		return src, fmt.Errorf("cannot unmarshal firstValue: %w", err)
+
+	firstValue, nSize := encoding.UnmarshalVarInt64(src)
+	if nSize <= 0 {
+		return src, fmt.Errorf("cannot unmarshal firstValue from varint")
 	}
+	src = src[nSize:]
 	bh.FirstValue = firstValue
-	src, rowsCount, err := encoding.UnmarshalVarUint64(src)
-	if err != nil {
-		return src, fmt.Errorf("cannot unmarshal rowsCount: %w", err)
+
+	rowsCount, nSize := encoding.UnmarshalVarUint64(src)
+	if nSize <= 0 {
+		return src, fmt.Errorf("cannot unmarshal rowsCount from varuint")
 	}
+	src = src[nSize:]
 	if rowsCount > math.MaxUint32 {
 		return src, fmt.Errorf("got too big rowsCount=%d; it mustn't exceed %d", rowsCount, uint32(math.MaxUint32))
 	}
 	bh.RowsCount = uint32(rowsCount)
-	src, scale, err := encoding.UnmarshalVarInt64(src)
-	if err != nil {
-		return src, fmt.Errorf("cannot unmarshal scale: %w", err)
+
+	scale, nSize := encoding.UnmarshalVarInt64(src)
+	if nSize <= 0 {
+		return src, fmt.Errorf("cannot unmarshal scale from varint")
 	}
+	src = src[nSize:]
 	if scale < math.MinInt16 {
 		return src, fmt.Errorf("got too small scale=%d; it mustn't be smaller than %d", scale, math.MinInt16)
 	}
@@ -204,6 +213,7 @@ func (bh *blockHeader) unmarshalPortable(src []byte) ([]byte, error) {
 	if len(src) < 1 {
 		return src, fmt.Errorf("cannot unmarshal marshalType for timestamps from %d bytes; need at least %d bytes", len(src), 1)
 	}
+
 	bh.TimestampsMarshalType = encoding.MarshalType(src[0])
 	src = src[1:]
 	if len(src) < 1 {
diff --git a/lib/storage/index_db.go b/lib/storage/index_db.go
index 758b9795f..449689786 100644
--- a/lib/storage/index_db.go
+++ b/lib/storage/index_db.go
@@ -2170,11 +2170,11 @@ func removeCompositeTagFilters(tfs []*tagFilter, prefix []byte) []*tagFilter {
 			continue
 		}
 		tagKey = tagKey[1:]
-		var nameLen uint64
-		tagKey, nameLen, err = encoding.UnmarshalVarUint64(tagKey)
-		if err != nil {
-			logger.Panicf("BUG: cannot unmarshal nameLen from tagKey %q: %s", tagKey, err)
+		nameLen, nSize := encoding.UnmarshalVarUint64(tagKey)
+		if nSize <= 0 {
+			logger.Panicf("BUG: cannot unmarshal nameLen from tagKey %q", tagKey)
 		}
+		tagKey = tagKey[nSize:]
 		if nameLen == 0 {
 			logger.Panicf("BUG: nameLen must be greater than 0")
 		}
@@ -2987,11 +2987,11 @@ func unmarshalCompositeTagKey(src []byte) ([]byte, []byte, error) {
 		return nil, nil, fmt.Errorf("missing composite tag key prefix in %q", src)
 	}
 	src = src[1:]
-	tail, n, err := encoding.UnmarshalVarUint64(src)
-	if err != nil {
-		return nil, nil, fmt.Errorf("cannot unmarshal metric name length from composite tag key: %w", err)
+	n, nSize := encoding.UnmarshalVarUint64(src)
+	if nSize <= 0 {
+		return nil, nil, fmt.Errorf("cannot unmarshal metric name length from composite tag key")
 	}
-	src = tail
+	src = src[nSize:]
 	if uint64(len(src)) < n {
 		return nil, nil, fmt.Errorf("missing metric name with length %d in composite tag key %q", n, src)
 	}
diff --git a/lib/storage/search.go b/lib/storage/search.go
index cbe95a27a..b12f58c6e 100644
--- a/lib/storage/search.go
+++ b/lib/storage/search.go
@@ -88,12 +88,12 @@ func MarshalBlock(dst []byte, b *Block) []byte {
 // Unmarshal unmarshals MetricBlock from src
 func (mb *MetricBlock) Unmarshal(src []byte) ([]byte, error) {
 	mb.Block.Reset()
-	tail, mn, err := encoding.UnmarshalBytes(src)
-	if err != nil {
-		return tail, fmt.Errorf("cannot unmarshal MetricName: %w", err)
+	mn, nSize := encoding.UnmarshalBytes(src)
+	if nSize <= 0 {
+		return src, fmt.Errorf("cannot unmarshal MetricName")
 	}
+	src = src[nSize:]
 	mb.MetricName = append(mb.MetricName[:0], mn...)
-	src = tail
 
 	return UnmarshalBlock(&mb.Block, src)
 }
@@ -108,19 +108,19 @@ func UnmarshalBlock(dst *Block, src []byte) ([]byte, error) {
 	}
 	src = tail
 
-	tail, tds, err := encoding.UnmarshalBytes(src)
-	if err != nil {
-		return tail, fmt.Errorf("cannot unmarshal timestampsData: %w", err)
+	tds, nSize := encoding.UnmarshalBytes(src)
+	if nSize <= 0 {
+		return tail, fmt.Errorf("cannot unmarshal timestampsData")
 	}
+	src = src[nSize:]
 	dst.timestampsData = append(dst.timestampsData[:0], tds...)
-	src = tail
 
-	tail, vd, err := encoding.UnmarshalBytes(src)
-	if err != nil {
-		return tail, fmt.Errorf("cannot unmarshal valuesData: %w", err)
+	vd, nSize := encoding.UnmarshalBytes(src)
+	if nSize <= 0 {
+		return tail, fmt.Errorf("cannot unmarshal valuesData")
 	}
+	src = src[nSize:]
 	dst.valuesData = append(dst.valuesData[:0], vd...)
-	src = tail
 
 	return src, nil
 }
@@ -365,19 +365,19 @@ func (tf *TagFilter) Marshal(dst []byte) []byte {
 
 // Unmarshal unmarshals tf from src and returns the tail.
 func (tf *TagFilter) Unmarshal(src []byte) ([]byte, error) {
-	tail, k, err := encoding.UnmarshalBytes(src)
-	if err != nil {
-		return tail, fmt.Errorf("cannot unmarshal Key: %w", err)
+	k, nSize := encoding.UnmarshalBytes(src)
+	if nSize <= 0 {
+		return src, fmt.Errorf("cannot unmarshal Key")
 	}
+	src = src[nSize:]
 	tf.Key = append(tf.Key[:0], k...)
-	src = tail
 
-	tail, v, err := encoding.UnmarshalBytes(src)
-	if err != nil {
-		return tail, fmt.Errorf("cannot unmarshal Value: %w", err)
+	v, nSize := encoding.UnmarshalBytes(src)
+	if nSize <= 0 {
+		return src, fmt.Errorf("cannot unmarshal Value")
 	}
+	src = src[nSize:]
 	tf.Value = append(tf.Value[:0], v...)
-	src = tail
 
 	if len(src) < 1 {
 		return src, fmt.Errorf("cannot unmarshal IsNegative+IsRegexp from empty src")
@@ -445,42 +445,42 @@ func (sq *SearchQuery) Unmarshal(src []byte) ([]byte, error) {
 	if len(src) < 4 {
 		return src, fmt.Errorf("cannot unmarshal AccountID: too short src len: %d; must be at least %d bytes", len(src), 4)
 	}
-	sq.AccountID = encoding.UnmarshalUint32(src)
 	src = src[4:]
+	sq.AccountID = encoding.UnmarshalUint32(src)
 
 	if len(src) < 4 {
 		return src, fmt.Errorf("cannot unmarshal ProjectID: too short src len: %d; must be at least %d bytes", len(src), 4)
 	}
-	sq.ProjectID = encoding.UnmarshalUint32(src)
 	src = src[4:]
+	sq.ProjectID = encoding.UnmarshalUint32(src)
 
-	tail, minTs, err := encoding.UnmarshalVarInt64(src)
-	if err != nil {
-		return src, fmt.Errorf("cannot unmarshal MinTimestamp: %w", err)
+	minTs, nSize := encoding.UnmarshalVarInt64(src)
+	if nSize <= 0 {
+		return src, fmt.Errorf("cannot unmarshal MinTimestamp from varint")
 	}
+	src = src[nSize:]
 	sq.MinTimestamp = minTs
-	src = tail
 
-	tail, maxTs, err := encoding.UnmarshalVarInt64(src)
-	if err != nil {
-		return src, fmt.Errorf("cannot unmarshal MaxTimestamp: %w", err)
+	maxTs, nSize := encoding.UnmarshalVarInt64(src)
+	if nSize <= 0 {
+		return src, fmt.Errorf("cannot unmarshal MaxTimestamp from varint")
 	}
+	src = src[nSize:]
 	sq.MaxTimestamp = maxTs
-	src = tail
 
-	tail, tfssCount, err := encoding.UnmarshalVarUint64(src)
-	if err != nil {
-		return src, fmt.Errorf("cannot unmarshal the count of TagFilterss: %w", err)
+	tfssCount, nSize := encoding.UnmarshalVarUint64(src)
+	if nSize <= 0 {
+		return src, fmt.Errorf("cannot unmarshal the count of TagFilterss from uvarint")
 	}
+	src = src[nSize:]
 	sq.TagFilterss = slicesutil.SetLength(sq.TagFilterss, int(tfssCount))
-	src = tail
 
 	for i := 0; i < int(tfssCount); i++ {
-		tail, tfsCount, err := encoding.UnmarshalVarUint64(src)
-		if err != nil {
-			return src, fmt.Errorf("cannot unmarshal the count of TagFilters: %w", err)
+		tfsCount, nSize := encoding.UnmarshalVarUint64(src)
+		if nSize <= 0 {
+			return src, fmt.Errorf("cannot unmarshal the count of TagFilters from uvarint")
 		}
-		src = tail
+		src = src[nSize:]
 
 		tagFilters := sq.TagFilterss[i]
 		tagFilters = slicesutil.SetLength(tagFilters, int(tfsCount))
diff --git a/lib/storage/storage.go b/lib/storage/storage.go
index 7848f383e..6e2f6303c 100644
--- a/lib/storage/storage.go
+++ b/lib/storage/storage.go
@@ -1683,25 +1683,26 @@ func UnmarshalMetricRows(dst []MetricRow, src []byte, maxRows int) ([]MetricRow,
 //
 // mr refers to src, so it remains valid until src changes.
 func (mr *MetricRow) UnmarshalX(src []byte) ([]byte, error) {
-	tail, metricNameRaw, err := encoding.UnmarshalBytes(src)
-	if err != nil {
-		return tail, fmt.Errorf("cannot unmarshal MetricName: %w", err)
+	metricNameRaw, nSize := encoding.UnmarshalBytes(src)
+	if nSize <= 0 {
+		return src, fmt.Errorf("cannot unmarshal MetricName")
 	}
+	tail := src[nSize:]
 	mr.MetricNameRaw = metricNameRaw
 
 	if len(tail) < 8 {
 		return tail, fmt.Errorf("cannot unmarshal Timestamp: want %d bytes; have %d bytes", 8, len(tail))
 	}
 	timestamp := encoding.UnmarshalUint64(tail)
-	mr.Timestamp = int64(timestamp)
 	tail = tail[8:]
+	mr.Timestamp = int64(timestamp)
 
 	if len(tail) < 8 {
 		return tail, fmt.Errorf("cannot unmarshal Value: want %d bytes; have %d bytes", 8, len(tail))
 	}
 	value := encoding.UnmarshalUint64(tail)
-	mr.Value = math.Float64frombits(value)
 	tail = tail[8:]
+	mr.Value = math.Float64frombits(value)
 
 	return tail, nil
 }
diff --git a/lib/streamaggr/streamaggr.go b/lib/streamaggr/streamaggr.go
index 261967853..f7110290e 100644
--- a/lib/streamaggr/streamaggr.go
+++ b/lib/streamaggr/streamaggr.go
@@ -867,22 +867,23 @@ func decompressLabels(dst []prompbmarshal.Label, key string) []prompbmarshal.Lab
 
 func getOutputKey(key string) string {
 	src := bytesutil.ToUnsafeBytes(key)
-	tail, inputKeyLen, err := encoding.UnmarshalVarUint64(src)
-	if err != nil {
-		logger.Panicf("BUG: cannot unmarshal inputKeyLen: %s", err)
+	inputKeyLen, nSize := encoding.UnmarshalVarUint64(src)
+	if nSize <= 0 {
+		logger.Panicf("BUG: cannot unmarshal inputKeyLen from uvarint")
 	}
-	outputKey := tail[inputKeyLen:]
+	outputKey := src[inputKeyLen:]
 	return bytesutil.ToUnsafeString(outputKey)
 }
 
 func getInputOutputKey(key string) (string, string) {
 	src := bytesutil.ToUnsafeBytes(key)
-	tail, inputKeyLen, err := encoding.UnmarshalVarUint64(src)
-	if err != nil {
-		logger.Panicf("BUG: cannot unmarshal inputKeyLen: %s", err)
+	inputKeyLen, nSize := encoding.UnmarshalVarUint64(src)
+	if nSize <= 0 {
+		logger.Panicf("BUG: cannot unmarshal inputKeyLen from uvarint")
 	}
-	inputKey := tail[:inputKeyLen]
-	outputKey := tail[inputKeyLen:]
+	src = src[nSize:]
+	inputKey := src[:inputKeyLen]
+	outputKey := src[inputKeyLen:]
 	return bytesutil.ToUnsafeString(inputKey), bytesutil.ToUnsafeString(outputKey)
 }