From 98b7c3a89cdd4556042a7d89a405aa2ed4dc13ed Mon Sep 17 00:00:00 2001
From: Yuce Tekol <yucetekol@gmail.com>
Date: Thu, 5 Feb 2026 15:18:39 +0300
Subject: [PATCH] Sort fields in compact schema by name

---
 src/serialization/compact/Schema.ts           | 10 +++++++---
 src/serialization/compact/SchemaWriter.ts     |  6 ++----
 .../compact/RabinFingerprintTest.js           | 19 +++++++++++++++++++
 test/unit/serialization/compact/SchemaTest.js |  4 +++-
 4 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/src/serialization/compact/Schema.ts b/src/serialization/compact/Schema.ts
index 4f3106064..e4f935acb 100644
--- a/src/serialization/compact/Schema.ts
+++ b/src/serialization/compact/Schema.ts
@@ -37,9 +37,13 @@ export class Schema {
     constructor(typeName: string, fields: FieldDescriptor[]) {
         this.typeName = typeName;
         this.fields = fields;
-        this.fieldDefinitionMap = new Map<string, FieldDescriptor>();
+        this.fields.sort((field1, field2) => {
+            return field1.fieldName > field2.fieldName ? 1 : -1;
+        })
 
-        for (const field of fields) {
+        this.fieldDefinitionMap = new Map<string, FieldDescriptor>();
+        for (const field of this.fields) {
+            // map entries are sorted by insertion order
             this.fieldDefinitionMap.set(field.fieldName, field);
         }
 
@@ -101,7 +105,7 @@ export class Schema {
     getFields() : IterableIterator<FieldDescriptor> {
         return this.fieldDefinitionMap.values();
     }
-    
+
     private hasSameFields(other: Schema): boolean {
         if (other.fieldDefinitionMap.size !== this.fieldDefinitionMap.size) {
             return false;
diff --git a/src/serialization/compact/SchemaWriter.ts b/src/serialization/compact/SchemaWriter.ts
index 744b19013..966ce9bcf 100644
--- a/src/serialization/compact/SchemaWriter.ts
+++ b/src/serialization/compact/SchemaWriter.ts
@@ -212,14 +212,12 @@ export class SchemaWriter implements CompactWriter {
                 'Field with the name ' + field.fieldName + ' already exists'
             );
         }
-            
+
         this.fieldNames.add(field.fieldName);
         this.fields.push(field);
     }
 
     build() : Schema {
-        return new Schema(this.typeName, this.fields.sort((field1, field2) => {
-            return field1.fieldName > field2.fieldName ? 1 : -1;
-        }));
+        return new Schema(this.typeName, this.fields);
     }
 }
diff --git a/test/unit/serialization/compact/RabinFingerprintTest.js b/test/unit/serialization/compact/RabinFingerprintTest.js
index aa7376992..f8e221ad7 100644
--- a/test/unit/serialization/compact/RabinFingerprintTest.js
+++ b/test/unit/serialization/compact/RabinFingerprintTest.js
@@ -19,6 +19,10 @@ const chai = require('chai');
 const Long = require('long');
 const { RabinFingerprint64, INIT } = require('../../../../lib/serialization/compact/RabinFingerprint');
 const { SchemaWriter } = require('../../../../lib/serialization/compact/SchemaWriter');
+const {Schema} = require('../../../../lib/serialization/compact/Schema');
+const {FieldDescriptor} = require('../../../../lib/serialization/generic_record/FieldDescriptor');
+const {FieldKind} = require('../../../../lib/serialization/generic_record/FieldKind');
+
 chai.should();
 
 describe('RabinFingerprintTest', function () {
@@ -88,4 +92,19 @@ describe('RabinFingerprintTest', function () {
         const schema = writer.build();
         schema.schemaId.eq(Long.fromString('3662264393229655598')).should.be.true;
     });
+
+    it('should compute the same fingerprint for equivalent schemas regardless of the field order', function () {
+        const schema1 = new Schema('my-schema', [
+            new FieldDescriptor('field-1', FieldKind.ARRAY_OF_DATE),
+            new FieldDescriptor('field-2', FieldKind.ARRAY_OF_DATE),
+        ]);
+        const fp1 = RabinFingerprint64.ofSchema(schema1);
+
+        const schema2 = new Schema('my-schema', [
+            new FieldDescriptor('field-2', FieldKind.ARRAY_OF_DATE),
+            new FieldDescriptor('field-1', FieldKind.ARRAY_OF_DATE),
+        ]);
+        const fp2 = RabinFingerprint64.ofSchema(schema2);
+        fp1.eq(fp2).should.be.true;
+    });
 });
diff --git a/test/unit/serialization/compact/SchemaTest.js b/test/unit/serialization/compact/SchemaTest.js
index 0581ea6bf..2f7c0bffc 100644
--- a/test/unit/serialization/compact/SchemaTest.js
+++ b/test/unit/serialization/compact/SchemaTest.js
@@ -27,7 +27,9 @@ describe('SchemaTest', function () {
         const boolCount = 100;
         const boolFields = new Array(100);
         for (let i = 0; i < boolCount; i++) {
-            boolFields[i] = new FieldDescriptor(i.toString(), FieldKind.BOOLEAN);
+            // the fields are sorted by name, so have to append 0 for numbers < 10
+            const name = i >= 10? i.toString() : '0' + i.toString();
+            boolFields[i] = new FieldDescriptor(name, FieldKind.BOOLEAN);
         }
 
         const fields = [