ClickHouse / ClickHouse/clickhouse-java

[client-v2, jdbc-v2] Make execution TIMEOUT error optionally retriable

Open
#3,072 0 comments 0 reactions 0 assignees View on GitHub
area:general client-api-v2 jdbc-v2
Dominant language
Java
Stars
1.6k
Forks
636
Avg merge
2d 16h
Merged PRs (30d)
28

Description

## Description

Current `159, TIMEOUT_EXCEEDED` is retried unconditionally. It should be a dedicated failure cause selectable per operation because different queries need different behavior:

| Query Type | Scenario | Retriable? | Recommended Action |
| :--- | :--- | :---: | :--- |
| **`SELECT`** | Pure read operations | **Yes** | Retry with exponential backoff or redirect to a replica node. |
| **`SELECT`** | Heavy unoptimized query hitting `max_execution_time` | **No** | Do not retry under identical settings. Increase `max_execution_time` or rewrite query. |
| **`INSERT`** | MergeTree tables with deduplication active (`insert_deduplicate = 1`) | **Yes** | Safe to retry using the exact same data block structure. |
| **`INSERT`** | Tables without block deduplication | **No** | **Unsafe.** Partial blocks may have been written; retrying risks duplicate rows. Check table state first. |
| **`DDL / Mutations`** | `ALTER`, `OPTIMIZE`, or background mutations | **No** | Inspect system tables (`system.mutations`, `system.merges`) before re-executing. |

Contributor guide

Open the contributing guide

Assessment

This issue has not been assessed yet.

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.