refactor: analyze table #18514
Open
refactor: analyze table #18514
+725
−270
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
github-actions
bot
added
the
pr-refactor
zhyass
added
ci-benchmark
zhyass
added
ci-benchmark
zhyass
added
ci-benchmark
Docker Image for PR
|
Docker Image for PR
|
NDV (Number of Distinct Values) Statistics Accuracy Comparison ReportData Source and Methodology
Complete NDV Accuracy Comparison Table
Key Findings and AnalysisSignificant Performance Differences Detected1. tpcds_100 Shows Superior Accuracy Overall
2. tpcds_100_v2 Shows Mixed Performance
Critical Problem Areas in tpcds_100_v2
Areas Where tpcds_100_v2 Performs Better
Statistical Quality Impact
Conclusion
|
dantengsky
reviewed
Aug 12, 2025
Comment on lines
+139
to
+142
| let prev_snapshot_id = snapshot.prev_snapshot_id.map(|(id, _)| id); | ||
| if Some(table_statistics.snapshot_id) == prev_snapshot_id { | ||
| return Ok(PipelineBuildResult::create()); | ||
| } |
There was a problem hiding this comment.
Shall we compare with the current snapshot id?
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Outdated suggestions cannot be applied.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.
I hereby agree to the terms of the CLA available at: https://docs.databend.com/dev/policies/cla/
Summary
Summary:
This PR improves the
ANALYZE TABLEprocess by directly merging pre-collected block-level HyperLogLog (HLL) data, instead of relying on query-based calculations.Previously,
HLLstatistics were calculated dynamically duringANALYZE TABLEthrough queries.Now, the block-level HLL data is directly used to merge statistics, reducing calculation time.
Reduces the cost of
ANALYZE TABLEby leveraging existing statistics, enhancing performance, especially for large tables.Tests
Type of change
This change is