与拉取请求有关的事件

7月24日19:17 UTC至7月24日20:02 UTC期间，由于数据库模式变更，用户无法创建拉取请求。总计影响50,904名用户的113,930次拉取请求创建尝试，对拉取请求服务的所有请求平均错误率为1.75%，最大错误率为2.25%。现有的拉取请求及其他GitHub功能未受影响。通过回滚受影响数据库的变更，问题得以解决，拉取请求创建随即恢复。<br /><br />根本原因与向托管拉取请求数据的Vitess键空间执行回填工作流有关。回填Vitess命令遇到错误并增加了VReplication延迟，工作流于19:17 UTC被取消。取消操作执行了一个被误解的Vitess代码路径，删除了目标键空间的支撑表，留下不存在的引用，导致创建拉取请求时出错。缓解措施是执行命令删除对已删除表的vschema引用，使拉取请求创建得以恢复。<br /><br />我们正在为工具添加更强的预检验证以防止类似问题，并扩展较低环境支持，以便在推广至生产环境前提供更好的端到端测试覆盖。同时，我们也在修复回填迁移工具，以防止此特定代码路径引发问题。

原文Between July 24, 19:17 UTC and July 24, 20:02 UTC, users were unable to create pull requests due to a database schema change. In total, 113,930 pull request creation attempts were impacted across 50,904 users, with an average error rate of 1.75% and a maximum error rate of 2.25% for all requests to Pull Requests service. Existing pull requests and other GitHub functionality were not affected. The issue was resolved by reverting the change to the affected database, upon which pull request creation immediately resumed.<br /><br />The root cause was related to a backfill workflow into the Vitess keyspace hosting Pull Request data. The backfill Vitess command encountered errors and increased VReplication lag, and the workflow was canceled at 19:17 UTC. The cancellation executed a misunderstood Vitess codepath that dropped the backing table to the target keyspace, leaving a non-existent reference that resulted in errors creating Pull Requests. The mitigation was executing a command to drop the vschema reference to the dropped table, allowing Pull Request creation to resume.<br /><br />We are adding stronger pre-flight validation to our tooling to prevent similar issues and expanding lower-environment support to provide better test coverage end-to-end before promoting them to production. We're also fixing our backfill migration tooling to protect from this specific codepath.

影响Pull Requests的服务降级问题已得到缓解。我们正在持续监控以确保稳定性。

原文The degradation affecting Pull Requests has been mitigated. We are monitoring to ensure stability.

我们已采取缓解措施，并正在监控恢复情况。

原文We have applied a mitigation and are monitoring for recovery

Pull Requests 正经历可用性降级。我们正在继续调查。

原文Pull Requests is experiencing degraded availability. We are continuing to investigate.

我们正在调查创建拉取请求时出现的错误。

原文We are investigating errors creating pull requests

我们正在调查关于拉取请求性能下降的报告。

原文We are investigating reports of degraded performance for Pull Requests