fix: change DocumentStoreFileChunk columns to LONGTEXT

[KushagraaWadhwa]

Description

Fixes chatflow corruption when uploading large documents (>64KB) to Document Store by changing database column types from TEXT to LONGTEXT.

Problem

Users experience the following when uploading large markdown documents:

1. SyntaxError: Unterminated string in JSON at position 65527
2. The entire chatflow becomes corrupted and unopenable
3. All work is lost

Root Cause

The metadata and pageContent columns in DocumentStoreFileChunk used TEXT type:

• MySQL/MariaDB TEXT has a maximum size of 65,535 bytes (64KB)
• Error at position 65,527 indicates the limit was hit
• MySQL silently truncates data exceeding this limit
• Truncated JSON becomes malformed → application crashes

Changes

1. Entity Update: Changed column types from TEXT to LONGTEXT in DocumentStoreFileChunk.ts

   • pageContent: TEXT (64KB) → LONGTEXT (4GB)
   • metadata: TEXT (64KB) → LONGTEXT (4GB)

2. Database Migrations: Created migrations for MySQL and MariaDB

   • 1765000000000-FixDocumentStoreFileChunkLongText.ts (MySQL)
   • 1765000000000-FixDocumentStoreFileChunkLongText.ts (MariaDB)
   • Registered migrations in index files

3. Migration Safety:

   • Existing data is preserved
   • up() migration expands columns to LONGTEXT
   • down() migration reverts to TEXT if needed
   • PostgreSQL and SQLite unaffected (TEXT already unlimited)

Files Changed

• packages/server/src/database/entities/DocumentStoreFileChunk.ts
• packages/server/src/database/migrations/mysql/1765000000000-FixDocumentStoreFileChunkLongText.ts (new)
• packages/server/src/database/migrations/mysql/index.ts
• packages/server/src/database/migrations/mariadb/1765000000000-FixDocumentStoreFileChunkLongText.ts (new)
• packages/server/src/database/migrations/mariadb/index.ts

Testing

• [ ] Test with documents >64KB in Document Store
• [ ] Verify migration runs successfully on existing databases
• [ ] Confirm chatflows remain functional after migration
• [ ] Test rollback migration if needed

Migration Instructions

After merging, users need to run: pnpm typeorm:migration-run## Related Issues Fixes #2352

Type of Change

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature
• [ ] Breaking change
• [ ] Documentation update

Checklist

• [x] My code follows the project's style guidelines
• [x] I have performed a self-review of my code
• [x] No linter errors introduced
• [x] Database migrations follow TypeORM conventions
• [x] Backward compatible with existing data

[gemini-code-assist[bot]]

Summary of Changes

Hello @KushagraaWadhwa, I'm Gemini Code Assist[^1]! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a critical bug causing chatflow corruption when users upload large documents exceeding 64KB to the Document Store. The issue stemmed from MySQL/MariaDB's TEXT column type having a 64KB size limit, leading to data truncation and malformed JSON. The changes involve upgrading the relevant database columns to LONGTEXT to support significantly larger data, thereby preventing data loss and ensuring the stability of chatflows.

Highlights

• Database Column Type Expansion: The pageContent and metadata columns in the DocumentStoreFileChunk entity have been updated from TEXT to LONGTEXT to accommodate larger data volumes, specifically addressing issues with documents exceeding 64KB.
• New Database Migrations: Dedicated migration files (1765000000000-FixDocumentStoreFileChunkLongText.ts) have been introduced for both MySQL and MariaDB to apply the column type changes to the document_store_file_chunk table.
• Data Integrity and Backward Compatibility: The migrations are designed to preserve existing data during the up() process, expanding column types safely. A down() migration is also provided for reversion. PostgreSQL and SQLite databases are unaffected as their TEXT types already support larger sizes.

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