diff --git a/common/pinot/pinotQueryValidator.go b/common/pinot/pinotQueryValidator.go
index d869ff1c06c..e01fd32eef7 100644
--- a/common/pinot/pinotQueryValidator.go
+++ b/common/pinot/pinotQueryValidator.go
@@ -386,6 +386,12 @@ func processCustomString(comparisonExpr *sqlparser.ComparisonExpr, colNameStr st
 		Type: sqlparser.StrVal,
 		Val:  []byte("%" + colValStr + "%"),
 	}
+
+	if colValStr == "" {
+		return fmt.Sprintf("(JSON_MATCH(Attr, '\"$.%s\" is not null') "+
+			"AND REGEXP_LIKE(JSON_EXTRACT_SCALAR(Attr, '$.%s', 'string'), '^$'))", colNameStr, colNameStr)
+	}
+
 	return fmt.Sprintf("(JSON_MATCH(Attr, '\"$.%s\" is not null') "+
 		"AND REGEXP_LIKE(JSON_EXTRACT_SCALAR(Attr, '$.%s', 'string'), '%s*'))", colNameStr, colNameStr, colValStr)
 }
diff --git a/common/pinot/pinotQueryValidator_test.go b/common/pinot/pinotQueryValidator_test.go
index b7c7b1025b5..0705aa2b5a3 100644
--- a/common/pinot/pinotQueryValidator_test.go
+++ b/common/pinot/pinotQueryValidator_test.go
@@ -46,10 +46,14 @@ func TestValidateQuery(t *testing.T) {
 			query:     "WorkflowID = 'wid'",
 			validated: "WorkflowID = 'wid'",
 		},
-		"Case3: query with custom field": {
+		"Case3-1: query with custom field": {
 			query:     "CustomStringField = 'custom'",
 			validated: "(JSON_MATCH(Attr, '\"$.CustomStringField\" is not null') AND REGEXP_LIKE(JSON_EXTRACT_SCALAR(Attr, '$.CustomStringField', 'string'), 'custom*'))",
 		},
+		"Case3-2: query with custom field value is empty": {
+			query:     "CustomStringField = ''",
+			validated: "(JSON_MATCH(Attr, '\"$.CustomStringField\" is not null') AND REGEXP_LIKE(JSON_EXTRACT_SCALAR(Attr, '$.CustomStringField', 'string'), '^$'))",
+		},
 		"Case4: custom field query with or in string": {
 			query:     "CustomStringField='Or'",
 			validated: "(JSON_MATCH(Attr, '\"$.CustomStringField\" is not null') AND REGEXP_LIKE(JSON_EXTRACT_SCALAR(Attr, '$.CustomStringField', 'string'), 'Or*'))",