Retries and Idempotency

This guide explains how retries work in the SDK and when to enable idempotency.

Retry policy overview

Retries are powered by @ydbjs/retry with sensible defaults:

• Immediate retry for BAD_SESSION, SESSION_EXPIRED, ABORTED.
• Exponential backoff for OVERLOADED and gRPC RESOURCE_EXHAUSTED (starts at 1000 ms).
• Exponential backoff for all other retryable cases (starts at 10 ms).
• Budget is unlimited by default; pass budget to cap attempts.

Query retries depend on the idempotency flag:

• Always retried: ABORTED, OVERLOADED, UNAVAILABLE, BAD_SESSION, SESSION_BUSY.
• Conditionally retried (only with .idempotent(true)): SESSION_EXPIRED, UNDETERMINED, TIMEOUT.

See implementation: packages/retry/src/index.ts and packages/query/src/query.ts.

Marking single calls as idempotent

await sql`UPDATE counters SET v = v + 1 WHERE id = ${id}`
  .idempotent(true)
  .timeout(3000)

Inside sql.begin/sql.transaction, the per-call idempotency flag is ignored; configure idempotency at the transaction level and make your business logic idempotent (e.g., via idempotency keys).

Customizing retry strategy

import { retry, defaultRetryConfig, strategies } from '@ydbjs/retry'

await retry({
  ...defaultRetryConfig,
  budget: 5,
  strategy: strategies.exponential(200),
}, async (signal) => {
  return await sql`SELECT 1`.signal(signal)
})

Topic streaming

Topic readers/writers reconnect on failures and rebuild command queues. Use retryConfig on writer for fine tuning; keep producers idempotent with producerId + seqNo.

Best practices

• Prefer idempotent operations and use idempotency keys for at-least-once flows.
• Set explicit timeouts to constrain tail latencies.
• Log retries via on('retry') and enable DEBUG=ydbjs:* in staging.