What caused the sudden spike in error rates for Alation's Query Log Ingestion feature last week?

Introduction

The sudden spike in error rates for Alation's Query Log Ingestion feature last week is a critical issue that demands immediate attention and thorough analysis. As we delve into this problem, we'll follow a systematic approach to identify, validate, and address the root cause while considering both short-term fixes and long-term implications for our product ecosystem.

Step 1

Clarifying Questions (3 minutes)

• Looking at the timing, I'm thinking this could be related to a recent deployment. Has there been any significant update or change to the Query Log Ingestion feature or related systems in the past week?

Why it matters: Recent changes often correlate with sudden performance shifts. Expected answer: Yes, there was a deployment last Tuesday. Impact on approach: If confirmed, we'd focus on changes in that deployment.

• Considering the nature of the feature, I'm wondering about data volume. Have we seen any unusual spikes in query log volume from our customers recently?

Why it matters: Unexpected data volume could overwhelm our ingestion systems. Expected answer: No significant changes in overall volume. Impact on approach: If true, we'd look more at internal processing issues rather than input overload.

• Given that this is an ingestion feature, I'm curious about downstream impacts. Are we seeing any knock-on effects in data availability or quality for features that depend on ingested query logs?

Why it matters: Helps us understand the scope and severity of the issue. Expected answer: Yes, some reporting features are showing incomplete data. Impact on approach: This would prioritize our investigation and potentially widen its scope.

• Thinking about our system architecture, I'm wondering about dependencies. Have there been any changes or issues with dependent services or infrastructure components?

Why it matters: Issues in dependent systems could manifest in our feature. Expected answer: There was a database upgrade in a related service. Impact on approach: We'd need to investigate potential compatibility issues or performance impacts from this upgrade.