diff --git a/lib/logstorage/logfmt_parser.go b/lib/logstorage/logfmt_parser.go
new file mode 100644
index 000000000..5eede8bbb
--- /dev/null
+++ b/lib/logstorage/logfmt_parser.go
@@ -0,0 +1,77 @@
+package logstorage
+
+import (
+	"strings"
+	"sync"
+)
+
+type logfmtParser struct {
+	fields []Field
+}
+
+func (p *logfmtParser) reset() {
+	clear(p.fields)
+	p.fields = p.fields[:0]
+}
+
+func (p *logfmtParser) addField(name, value string) {
+	p.fields = append(p.fields, Field{
+		Name:  name,
+		Value: value,
+	})
+}
+
+func (p *logfmtParser) parse(s string) {
+	for {
+		// Search for field name
+		n := strings.IndexByte(s, '=')
+		if n < 0 {
+			// field name couldn't be read
+			return
+		}
+
+		name := strings.TrimSpace(s[:n])
+		s = s[n+1:]
+		if len(s) == 0 {
+			p.addField(name, "")
+			return
+		}
+
+		// Search for field value
+		value, nOffset := tryUnquoteString(s)
+		if nOffset >= 0 {
+			p.addField(name, value)
+			s = s[nOffset:]
+			if len(s) == 0 {
+				return
+			}
+			if s[0] != ' ' {
+				return
+			}
+			s = s[1:]
+		} else {
+			n := strings.IndexByte(s, ' ')
+			if n < 0 {
+				p.addField(name, s)
+				return
+			}
+			p.addField(name, s[:n])
+			s = s[n+1:]
+		}
+	}
+}
+
+func getLogfmtParser() *logfmtParser {
+	v := logfmtParserPool.Get()
+	if v == nil {
+		return &logfmtParser{}
+	}
+	return v.(*logfmtParser)
+}
+
+func putLogfmtParser(p *logfmtParser) {
+	p.reset()
+	logfmtParserPool.Put(p)
+}
+
+var logfmtParserPool sync.Pool
diff --git a/lib/logstorage/logfmt_parser_test.go b/lib/logstorage/logfmt_parser_test.go
new file mode 100644
index 000000000..60161271e
--- /dev/null
+++ b/lib/logstorage/logfmt_parser_test.go
@@ -0,0 +1,30 @@
+package logstorage
+
+import (
+	"testing"
+)
+
+func TestLogfmtParser(t *testing.T) {
+	f := func(s, resultExpected string) {
+		t.Helper()
+
+		p := getLogfmtParser()
+		defer putLogfmtParser(p)
+
+		p.parse(s)
+		result := marshalFieldsToJSON(nil, p.fields)
+		if string(result) != resultExpected {
+			t.Fatalf("unexpected result when parsing [%s]; got\n%s\nwant\n%s\n", s, result, resultExpected)
+		}
+	}
+
+	f(``, `{}`)
+	f(`foo=bar`, `{"foo":"bar"}`)
+	f(`foo="bar=baz x=y"`, `{"foo":"bar=baz x=y"}`)
+	f(`foo=`, `{"foo":""}`)
+	f(`foo=bar baz="x y" a=b`, `{"foo":"bar","baz":"x y","a":"b"}`)
+
+	// errors
+	f(`foo`, `{}`)
+	f(`foo=bar  baz=x z qwe`, `{"foo":"bar","baz":"x"}`)
+}
diff --git a/lib/logstorage/pipe_unpack_json.go b/lib/logstorage/pipe_unpack_json.go
index dd6cdab3e..790950c45 100644
--- a/lib/logstorage/pipe_unpack_json.go
+++ b/lib/logstorage/pipe_unpack_json.go
@@ -44,15 +44,44 @@ func (pu *pipeUnpackJSON) String() string {
 }
 
 func (pu *pipeUnpackJSON) updateNeededFields(neededFields, unneededFields fieldsSet) {
+	updateNeededFieldsForUnpackPipe(pu.fromField, pu.fields, pu.iff, neededFields, unneededFields)
+}
+
+func updateNeededFieldsForUnpackPipe(fromField string, outFields []string, iff *ifFilter, neededFields, unneededFields fieldsSet) {
 	if neededFields.contains("*") {
-		unneededFields.remove(pu.fromField)
-		if pu.iff != nil {
-			unneededFields.removeFields(pu.iff.neededFields)
+		unneededFieldsOrig := unneededFields.clone()
+		unneededFieldsCount := 0
+		if len(outFields) > 0 {
+			for _, f := range outFields {
+				if unneededFieldsOrig.contains(f) {
+					unneededFieldsCount++
+				}
+				unneededFields.add(f)
+			}
+		}
+		if len(outFields) == 0 || unneededFieldsCount < len(outFields) {
+			unneededFields.remove(fromField)
+			if iff != nil {
+				unneededFields.removeFields(iff.neededFields)
+			}
 		}
 	} else {
-		neededFields.add(pu.fromField)
-		if pu.iff != nil {
-			neededFields.addFields(pu.iff.neededFields)
+		neededFieldsOrig := neededFields.clone()
+		needFromField := len(outFields) == 0
+		if len(outFields) > 0 {
+			needFromField = false
+			for _, f := range outFields {
+				if neededFieldsOrig.contains(f) {
+					needFromField = true
+				}
+				neededFields.remove(f)
+			}
+		}
+		if needFromField {
+			neededFields.add(fromField)
+			if iff != nil {
+				neededFields.addFields(iff.neededFields)
+			}
 		}
 	}
 }
@@ -64,19 +93,29 @@ func (pu *pipeUnpackJSON) newPipeProcessor(workersCount int, _ <-chan struct{},
 			return
 		}
 		p := GetJSONParser()
-		if err := p.ParseLogMessage(bytesutil.ToUnsafeBytes(s)); err == nil {
+		err := p.ParseLogMessage(bytesutil.ToUnsafeBytes(s))
+		if err != nil {
+			for _, fieldName := range pu.fields {
+				uctx.addField(fieldName, "")
+			}
+		} else {
 			if len(pu.fields) == 0 {
 				for _, f := range p.Fields {
 					uctx.addField(f.Name, f.Value)
 				}
 			} else {
 				for _, fieldName := range pu.fields {
+					addedField := false
 					for _, f := range p.Fields {
 						if f.Name == fieldName {
 							uctx.addField(f.Name, f.Value)
+							addedField = true
 							break
 						}
 					}
+					if !addedField {
+						uctx.addField(fieldName, "")
+					}
 				}
 			}
 		}
diff --git a/lib/logstorage/pipe_unpack_json_test.go b/lib/logstorage/pipe_unpack_json_test.go
index d0c06d01d..53650f071 100644
--- a/lib/logstorage/pipe_unpack_json_test.go
+++ b/lib/logstorage/pipe_unpack_json_test.go
@@ -64,6 +64,7 @@ func TestPipeUnpackJSON(t *testing.T) {
 		{
 			{"_msg", `{"foo":"bar","z":"q","a":"b"}`},
 			{"foo", "bar"},
+			{"b", ""},
 		},
 	})
 
@@ -465,24 +466,34 @@ func TestPipeUnpackJSONUpdateNeededFields(t *testing.T) {
 	// all the needed fields
 	f("unpack_json from x", "*", "", "*", "")
 	f("unpack_json if (y:z) from x", "*", "", "*", "")
+	f("unpack_json if (y:z) from x fields (a, b)", "*", "", "*", "a,b")
 
 	// all the needed fields, unneeded fields do not intersect with src
 	f("unpack_json from x", "*", "f1,f2", "*", "f1,f2")
 	f("unpack_json if (y:z) from x", "*", "f1,f2", "*", "f1,f2")
 	f("unpack_json if (f1:z) from x", "*", "f1,f2", "*", "f2")
+	f("unpack_json if (y:z) from x fields (f3)", "*", "f1,f2", "*", "f1,f2,f3")
+	f("unpack_json if (y:z) from x fields (f1)", "*", "f1,f2", "*", "f1,f2")
 
 	// all the needed fields, unneeded fields intersect with src
 	f("unpack_json from x", "*", "f2,x", "*", "f2")
 	f("unpack_json if (y:z) from x", "*", "f2,x", "*", "f2")
 	f("unpack_json if (f2:z) from x", "*", "f1,f2,x", "*", "f1")
+	f("unpack_json if (f2:z) from x fields (f3)", "*", "f1,f2,x", "*", "f1,f3")
 
 	// needed fields do not intersect with src
 	f("unpack_json from x", "f1,f2", "", "f1,f2,x", "")
 	f("unpack_json if (y:z) from x", "f1,f2", "", "f1,f2,x,y", "")
 	f("unpack_json if (f1:z) from x", "f1,f2", "", "f1,f2,x", "")
+	f("unpack_json if (y:z) from x fields (f3)", "f1,f2", "", "f1,f2", "")
+	f("unpack_json if (y:z) from x fields (f2)", "f1,f2", "", "f1,x,y", "")
+	f("unpack_json if (f2:z) from x fields (f2)", "f1,f2", "", "f1,f2,x", "")
 
 	// needed fields intersect with src
 	f("unpack_json from x", "f2,x", "", "f2,x", "")
 	f("unpack_json if (y:z) from x", "f2,x", "", "f2,x,y", "")
 	f("unpack_json if (f2:z y:qwe) from x", "f2,x", "", "f2,x,y", "")
+	f("unpack_json if (y:z) from x fields (f1)", "f2,x", "", "f2,x", "")
+	f("unpack_json if (y:z) from x fields (f2)", "f2,x", "", "x,y", "")
+	f("unpack_json if (y:z) from x fields (x)", "f2,x", "", "f2,x,y", "")
 }
diff --git a/lib/logstorage/pipe_unpack_logfmt.go b/lib/logstorage/pipe_unpack_logfmt.go
index 984df2498..bc294a9b5 100644
--- a/lib/logstorage/pipe_unpack_logfmt.go
+++ b/lib/logstorage/pipe_unpack_logfmt.go
@@ -3,7 +3,6 @@ package logstorage
 import (
 	"fmt"
 	"slices"
-	"strings"
 )
 
 // pipeUnpackLogfmt processes '| unpack_logfmt ...' pipe.
@@ -43,63 +42,35 @@ func (pu *pipeUnpackLogfmt) String() string {
 }
 
 func (pu *pipeUnpackLogfmt) updateNeededFields(neededFields, unneededFields fieldsSet) {
-	if neededFields.contains("*") {
-		unneededFields.remove(pu.fromField)
-		if pu.iff != nil {
-			unneededFields.removeFields(pu.iff.neededFields)
-		}
-	} else {
-		neededFields.add(pu.fromField)
-		if pu.iff != nil {
-			neededFields.addFields(pu.iff.neededFields)
-		}
-	}
+	updateNeededFieldsForUnpackPipe(pu.fromField, pu.fields, pu.iff, neededFields, unneededFields)
 }
 
 func (pu *pipeUnpackLogfmt) newPipeProcessor(workersCount int, _ <-chan struct{}, _ func(), ppBase pipeProcessor) pipeProcessor {
-	addField := func(uctx *fieldsUnpackerContext, name, value string) {
-		if len(pu.fields) == 0 || slices.Contains(pu.fields, name) {
-			uctx.addField(name, value)
-		}
-	}
-
 	unpackLogfmt := func(uctx *fieldsUnpackerContext, s string) {
-		for {
-			// Search for field name
-			n := strings.IndexByte(s, '=')
-			if n < 0 {
-				// field name couldn't be read
-				return
-			}
+		p := getLogfmtParser()
 
-			name := strings.TrimSpace(s[:n])
-			s = s[n+1:]
-			if len(s) == 0 {
-				addField(uctx, name, "")
+		p.parse(s)
+		if len(pu.fields) == 0 {
+			for _, f := range p.fields {
+				uctx.addField(f.Name, f.Value)
 			}
-
-			// Search for field value
-			value, nOffset := tryUnquoteString(s)
-			if nOffset >= 0 {
-				addField(uctx, name, value)
-				s = s[nOffset:]
-				if len(s) == 0 {
-					return
+		} else {
+			for _, fieldName := range pu.fields {
+				addedField := false
+				for _, f := range p.fields {
+					if f.Name == fieldName {
+						uctx.addField(f.Name, f.Value)
+						addedField = true
+						break
+					}
 				}
-				if s[0] != ' ' {
-					return
+				if !addedField {
+					uctx.addField(fieldName, "")
 				}
-				s = s[1:]
-			} else {
-				n := strings.IndexByte(s, ' ')
-				if n < 0 {
-					addField(uctx, name, s)
-					return
-				}
-				addField(uctx, name, s[:n])
-				s = s[n+1:]
 			}
 		}
+
+		putLogfmtParser(p)
 	}
 
 	return newPipeUnpackProcessor(workersCount, unpackLogfmt, ppBase, pu.fromField, pu.resultPrefix, pu.iff)
diff --git a/lib/logstorage/pipe_unpack_logfmt_test.go b/lib/logstorage/pipe_unpack_logfmt_test.go
index ff1711d69..a5c7426f8 100644
--- a/lib/logstorage/pipe_unpack_logfmt_test.go
+++ b/lib/logstorage/pipe_unpack_logfmt_test.go
@@ -63,6 +63,7 @@ func TestPipeUnpackLogfmt(t *testing.T) {
 			{"_msg", `foo=bar baz="x y=z" a=b`},
 			{"foo", "bar"},
 			{"a", "b"},
+			{"b", ""},
 		},
 	})