suxiaogang223 opened a new pull request, #58759:
URL: https://github.com/apache/doris/pull/58759
### What problem does this PR solve?
Problem Summary:
When querying external tables, if `file_split_size` is set too small, large
files will be split into a huge number of splits. In non-batch mode, all splits
are loaded into memory at once, which can cause OOM when there are too many
splits.
## Solution
Add `max_file_splits_num` configuration to limit the total number of splits
across all files. The system will perform a global assessment before generating
splits:
1. **Collect file information**: Gather file sizes before splitting
2. **Estimate total split count**: Calculate estimated total splits based on
total file size and `file_split_size`
3. **Dynamic adjustment**: If the estimated split count exceeds
`max_file_splits_num`, automatically increase `file_split_size` to
`ceil(total_file_size / max_file_splits_num)`
4. **Execute split**: Use the adjusted split size for splitting
## Main Changes
- **SessionVariable.java**: Add `max_file_splits_num` configuration
(default: 100000)
- **FileQueryScanNode.java**: Add `adjustSplitSizeForTotalLimit()` method to
estimate and adjust split size
- **HiveScanNode.java**: Collect file information and adjust split size
before splitting
- **TVFScanNode.java**: Collect file information and adjust split size
before splitting
- **PaimonScanNode.java**: Collect file information and adjust split size
before splitting
## Usage
-- Set maximum total split count (default: 1000000)
SET max_file_splits_num = 1000000;
-- Set to 0 to disable the limit
SET max_file_splits_num = 0;
### Release note
None
### Check List (For Author)
- Test <!-- At least one of them must be included. -->
- [ ] Regression test
- [ ] Unit Test
- [ ] Manual test (add detailed scripts or steps below)
- [ ] No need to test or manual test. Explain why:
- [ ] This is a refactor/code format and no logic has been changed.
- [ ] Previous test can cover this change.
- [ ] No code files have been changed.
- [ ] Other reason <!-- Add your reason? -->
- Behavior changed:
- [ ] No.
- [ ] Yes. <!-- Explain the behavior change -->
- Does this need documentation?
- [ ] No.
- [ ] Yes. <!-- Add document PR link here. eg:
https://github.com/apache/doris-website/pull/1214 -->
### Check List (For Reviewer who merge this PR)
- [ ] Confirm the release note
- [ ] Confirm test cases
- [ ] Confirm document
- [ ] Add branch pick label <!-- Add branch pick label that this PR should
merge into -->
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