Usage report calculates negative endpoint throughput after queue table deletion#5516
Open
jasontaylordev wants to merge 1 commit into
Open
Usage report calculates negative endpoint throughput after queue table deletion#5516jasontaylordev wants to merge 1 commit into
jasontaylordev wants to merge 1 commit into
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Symptoms
Usage reports can contain negative throughput values for an endpoint/queue.
This can happen when a queue table is deleted between throughput snapshots.
Who's affected
Users generating usage reports where queue tables may have been deleted during the reporting period.
Root cause
Throughput is calculated by comparing two snapshots taken an hour apart.
When a queue table is deleted, the end-of-hour total is not set and defaults to 0, causing the calculation to produce a negative throughput value.
Confirmed workarounds
None
Original bug report
While calculating throughput, when a queue table is deleted, we see a negative throughput entry recorded in the usage report for the day.This happens because we take two snapshots, an hour apart, and then use this to figure out how many messages have been processed:
When a table gets deleted, the sequence no longer exists and querying it throws a PostgreSQL 42P01 exception. This exception is caught and the end-of-hour total is left unset, defaulting to 0. This ends up looking like this:
That is always going to be a negative number, and one that is not representative of the throughput in that hour.