libSQL by xexr

Implements connection pooling for libSQL databases across three backend types: local file-based SQLite, local HTTP servers, and remote Turso cloud databases. Uses a pool manager pattern to maintain persistent connections with configurable pool sizes, reducing connection overhead for repeated queries. Automatically handles connection lifecycle management including idle timeout, reconnection on failure, and graceful shutdown.

Executes SQL queries against pooled libSQL connections with full ACID transaction support including explicit BEGIN/COMMIT/ROLLBACK semantics. Implements transaction state tracking to prevent nested transaction errors and provides row-level result streaming for large result sets. Supports parameterized queries to prevent SQL injection while maintaining query performance through prepared statement caching.

Queries libSQL system tables (sqlite_master, pragma statements) to extract comprehensive database schema metadata including table definitions, column types, indexes, constraints, and relationships. Returns structured metadata objects that describe the complete database structure without requiring external schema files or manual documentation. Caches schema metadata to reduce repeated system table queries.

Creates full database backups by copying the entire database file (for file-based backends) or exporting via SQL dump (for HTTP/Turso backends). Supports incremental backup strategies by tracking modification timestamps and selective export of changed tables. Implements point-in-time recovery by maintaining backup metadata including timestamps and transaction IDs, enabling restoration to specific points in database history.

Implements cursor-based pagination for large result sets by maintaining server-side query state and returning configurable page sizes. Supports streaming results via iterator pattern to avoid loading entire datasets into memory, with automatic cursor management and position tracking. Enables efficient processing of million-row tables by yielding results in batches rather than materializing complete result sets.

Manages database schema evolution through versioned migration files that track schema changes over time. Implements a migration state table to record which migrations have been applied, preventing duplicate execution and enabling rollback to previous schema versions. Supports both forward migrations (schema upgrades) and backward migrations (rollbacks) with automatic dependency resolution and conflict detection.

Enforces row-level security policies by filtering query results based on user identity and permissions. Implements column-level masking to redact sensitive data (PII, credentials) from query results based on user roles. Uses a policy engine that evaluates security rules before returning data, preventing unauthorized access at the database layer rather than application layer.

Captures query execution metrics including execution time, rows scanned, and index usage patterns. Analyzes query performance against configurable thresholds to identify slow queries and missing indexes. Generates optimization suggestions based on execution plans and table statistics, such as recommending indexes on frequently filtered columns or suggesting query rewrites for inefficient joins.

Manages concurrent query execution across multiple clients while maintaining ACID isolation guarantees. Implements a transaction scheduler that serializes conflicting transactions and allows concurrent execution of non-conflicting operations. Detects and prevents deadlocks through dependency graph analysis and automatic transaction ordering. Provides isolation level configuration (READ UNCOMMITTED, READ COMMITTED, REPEATABLE READ, SERIALIZABLE) to balance consistency and performance.