suxiaogang223 opened a new pull request, #57972:
URL: https://github.com/apache/doris/pull/57972
### What problem does this PR solve?
## Summary
This PR implements support for partition evolution in Iceberg tables,
allowing users to dynamically modify table partition strategies without
rewriting data files. This is a metadata-only operation that maintains multiple
partition spec versions.
## Background
Apache Iceberg supports partition evolution, which enables changing
partition strategies on existing tables without data migration. Doris, as a
query engine for Iceberg, needs to support SQL syntax for partition evolution
operations to provide users with flexible partition management.
## Features
### Core Functionality
- **Add Partition Field**: Add new partition fields to existing partition
specifications
- **Drop Partition Field**: Remove partition fields from existing partition
specifications
### Design Principles
1. **Metadata-only operation**: Partition evolution only updates table
metadata, no data files are rewritten
2. **Backward compatibility**: Historical data retains original partition
specs, new data uses new partition specs
3. **Syntax compatibility**: Follows Spark SQL ALTER TABLE syntax for
consistency
## Syntax
### Add Partition Field
```sql
ALTER TABLE table_name ADD PARTITION FIELD partition_transform;
```
### Drop Partition Field
```sql
ALTER TABLE table_name DROP PARTITION FIELD partition_transform;
```
### Supported Partition Transforms
| Transform | Syntax | Example |
|-----------|--------|---------|
| bucket | `bucket(N, column)` | `bucket(16, id)` |
| truncate | `truncate(N, column)` | `truncate(10, name)` |
| year | `year(column)` or `years(column)` | `year(ts)` |
| month | `month(column)` or `months(column)` | `month(ts)` |
| day | `day(column)` or `days(column)` or `date(column)` | `day(ts)` |
| hour | `hour(column)` or `hours(column)` or `date_hour(column)` |
`hour(ts)` |
| identity | `column` | `category` |
### 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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