zwy991114 opened a new pull request, #67116:
URL: https://github.com/apache/doris/pull/67116
### What problem does this PR solve?
Problem Summary:
Doris dictionary (`CREATE DICTIONARY`) previously supported only the
`HASH_MAP` and `IP_TRIE` layouts. This PR adds a ClickHouse-style `FLAT` layout
for integer-keyed dictionaries.
In a `FLAT` dictionary, a single non-negative integer key is used directly
as an array index into column-wise value storage, with a presence bitmap
distinguishing absent keys from present-with-default keys. This avoids the
per-lookup hashing that `HASH_MAP` performs, making it a good fit for dense
integer surrogate keys (e.g. dimension-table enrichment).
### Release note
Support `FLAT` layout in `CREATE DICTIONARY` for integer-keyed dictionaries.
### Check List (For Author)
- Test <!-- At least one of them must be included. -->
- [x] Regression test
- [x] 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:
- [x] No.
- [ ] Yes. <!-- Explain the behavior change -->
- Does this need documentation?
- [ ] No.
- [x] 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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