doobidoo/mcp-memory-service v8.62.4

v8.62.4 - CRITICAL: SQLite-Vec KNN Syntax Fix

on GitHub

🔴 CRITICAL BUGFIX: Semantic Search Failure

Impact: Complete failure of semantic search operations on sqlite-vec and hybrid backends (affects majority of installations)

What Was Broken

Semantic search operations (retrieve_memory, recall_memory) completely failed with:

sqlite3.OperationalError: A LIMIT or 'k = ?' constraint is required on vec0 knn queries

Root Cause

SQLite-Vec v0.1.0+ introduced a breaking change requiring k = ? parameter syntax for KNN queries. The service was still using the deprecated LIMIT ? syntax.

What's Fixed

• ✅ Updated SqliteVecMemoryStorage.retrieve() to use k = ? parameter
• ✅ Updated SqliteVecMemoryStorage.recall() to use k = ? parameter
• ✅ Added integration tests (test_retrieve_knn_syntax, test_recall_knn_syntax) for regression prevention
• ✅ All semantic search operations restored to full functionality

Files Changed

• src/mcp_memory_service/storage/sqlite_vec_memory_storage.py (lines 245, 340)
• tests/integration/test_sqlite_vec_storage.py (new integration tests)

Severity & Impact

• Severity: Critical (P0)
• Affected Users: All users on sqlite-vec or hybrid backends (majority of installations)
• Regression Risk: Low - Integration tests now validate KNN syntax explicitly
• Upgrade Note: No action required - fix is backward compatible

Thanks

🙏 @feroult (Fernando Ultremare) - For identifying the issue and providing the critical fix

Related

• PR #308: Fix sqlite-vec KNN syntax error (merged)
• Issue #309: Documentation and CHANGELOG updates (this release)
• SQLite-Vec v0.1.0: Breaking change introduced k = ? requirement

Installation

pip install --upgrade mcp-memory-service

Or with uv (recommended):

uvx --from mcp-memory-service memory --version

Full Changelog: v8.62.3...v8.62.4

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