Compare performance: Detect 'shadowed' cache hits and a few other fixes #4018
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
The warning doesn't seem necessary anymore since shadowed cache hits are detected now
![github-advanced-security[bot]](https://avatars.githubusercontent.com/in/57789?s=60&v=4){kind=small}
extensions/ql-vscode/src/view/compare-performance/ComparePerformance.tsx
Fixed
Show fixed
Hide fixed
There's a linting check that fails if we export something without importing it anywhere.
aeisenberg
reviewed
Apr 28, 2025
extensions/ql-vscode/src/log-insights/performance-comparison.ts
Outdated
Show resolved
Hide resolved
Comment on lines
+886
to
+887
| // Note: we can't import "crypto" here because it is not available in the browser, | ||
| // so we just concatenate the hashes of the individual pipelines. |
There was a problem hiding this comment.
How long will this be? Can we possibly have 100s of keys? It might be safer to do some checks to ensure that the result is never larger than a fixed amount. And if it is, then you can sample the first n chars in each key to keep it under the limit, retain a reasonable amount of stochasticity, and ensure the result easy to reproduce given the same input.
There was a problem hiding this comment.
Back when the "standard order" existed there could be multiple pipelines, but nowadays there are 2 for recursive predicates and 1 for all other predicates. So it's really small.
extensions/ql-vscode/src/view/compare-performance/ComparePerformance.tsx
Outdated
Show resolved
Hide resolved
Co-authored-by: Andrew Eisenberg <aeisenberg@github.com>
aeisenberg
approved these changes
Apr 29, 2025
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
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.
Adds detection of 'shadowed' cache hits in the compare performance view, greatly improving its usefulness when comparing two query runs where the cache was not cleared in-between. Previously, one side of the comparison would get blamed for the cost of evaluating a lot of predicates that the other side could omit because of the cache. Detecting this is harder than it sounds, see explanation comment in 06fcd6f.
Also fixes a few other things, such as the
NAMED_LOCALnot being handled, and themillisfield referring to the entire SCC cost onCOMPUTE_RECURSIVEevents, which is not what we want.Commit-by-commit strongly recommended.