Connection Pooling#

PoolConfig configures connection pool behavior for pooled drivers.

PoolConfig Fields#

const PoolConfig(
  min: 2,
  max: 10,
  acquireTimeoutMillis: 60000,
  idleTimeoutMillis: null,
  reapIntervalMillis: 1000,
)

• min: minimum open connections to keep.
• max: maximum open connections.
• acquireTimeoutMillis: max wait time to get a connection from the pool.
• idleTimeoutMillis: how long an idle connection can stay open before cleanup.
• reapIntervalMillis: how often idle-connection cleanup runs.

PostgreSQL Example#

import 'package:knex_dart/knex_dart.dart' show PoolConfig;
import 'package:knex_dart_postgres/knex_dart_postgres.dart';

final db = await KnexPostgres.connect(
  host: 'localhost',
  database: 'app',
  username: 'postgres',
  password: 'secret',
  poolConfig: const PoolConfig(
    min: 2,
    max: 10,
    acquireTimeoutMillis: 30000,
    idleTimeoutMillis: 30000,
    reapIntervalMillis: 1000,
  ),
);

MySQL Example#

import 'package:knex_dart/knex_dart.dart' show PoolConfig;
import 'package:knex_dart_mysql/knex_dart_mysql.dart';

final db = await KnexMySQL.connect(
  host: 'localhost',
  user: 'root',
  password: 'secret',
  database: 'app',
  poolConfig: const PoolConfig(
    min: 2,
    max: 10,
    acquireTimeoutMillis: 30000,
    idleTimeoutMillis: 30000,
    reapIntervalMillis: 1000,
  ),
);

Drivers Without Pooling#

These drivers currently run without a connection pool (single-connection or request-based transport):

• knex_dart_sqlite
• knex_dart_duckdb
• knex_dart_mssql
• knex_dart_bigquery
• knex_dart_snowflake
• knex_dart_turso
• knex_dart_d1

Best Practices#

• Start with min: 2 to keep warm connections ready.
• Set max based on database limits and app concurrency.
• Use idleTimeoutMillis to clean up idle connections in bursty workloads.
• Keep reapIntervalMillis small (default 1000) for predictable idle cleanup.

Implementation note: PostgreSQL and MySQL both accept PoolConfig; MySQL currently uses all five fields directly, while PostgreSQL primarily uses max and acquireTimeoutMillis in its underlying pool settings.