[fix](statistics)Control memory use for sample partition column and key column. (#46534)#48927
Merged
yiguolei merged 1 commit intoapache:branch-2.1from Mar 14, 2025
Merged
Conversation
…ey column. (apache#46534) When doing sample analyze for partition column and key column, BE may encounter OOM problem. The reason is, partition column need to choose at least one tablet in each partition to calculate the NDV and couldn't use limit in the SQL, so when the table has large number of partitions and each tablet in each partition is quite large, the sample SQL may try to read too many data which will cause BE OOM. Similarly, key column couldn't use limit as well, so when one tablet is very large, it also could cause OOM. This pr is try to solve this problem. For partition columns, when the selected tablets contain more than 1000000000 (one billion) rows, we use ndv() function to read up to 5 partitions to get the NDV value of this 5 partitions, say the ndv is n. Suppose the row count in the 5 partitions is r, and the row count of tje table is R, the table NDV would be n * R / r. ndv() function use hll, so it only use a small amount of memory. For key columns, when the selected tablets contain more than 1000000000 rows, we use limit 1000000000 to control the rows to read. Reading 1000000000 rows would use at most 8GB memory in BE, which is acceptable. Issue Number: close #xxx Related PR: #xxx Problem Summary: None
Contributor
Author
|
run buildall |
Contributor
|
Thank you for your contribution to Apache Doris. Please clearly describe your PR:
|
yiguolei
approved these changes
Mar 14, 2025
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
3 participants
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.
backport: #46534