RoanHeNaN opened a new issue, #70500: URL: https://github.com/apache/doris/issues/70500
### Search before asking - [x] I had searched in the [issues](https://github.com/apache/doris/issues?q=is%3Aissue) and found no similar issues. ### Version branch-4.0 source (8a9961723ea4be00cdf923c60759607202c7e2e7); exact deployed patch version not collected. ### What's Wrong? information_schema.backend_tablets.COMPRESS_KIND reports COMPRESS_LZ4 even when the FE default_compression_type is ZSTD. This column is documented as the compression type, so the result suggests that the table uses LZ4 and makes it difficult to verify the actual compression setting. In branch-4.0, tablet_meta.cpp always sets TabletSchemaPB.compress_kind to COMPRESS_LZ4, while the configured algorithm is stored separately in TabletSchemaPB.compression_type. schema_tablets_scanner.cpp populates backend_tablets.COMPRESS_KIND from tablet->compress_kind(), so it reports the fixed metadata field instead of the segment page compression setting. SegmentWriter reads tablet_schema->compression_type() for page writing. This report concerns the system table result; it does not claim that page data is actually compressed with LZ4. ### What You Expected? Expose the configured segment page compression type (for example, ZSTD) in backend_tablets so users can inspect the effective tablet setting. A separate COMPRESSION_TYPE column would preserve the existing COMPRESS_KIND output for compatibility; alternatively, clarify the existing column semantics in the documentation. ### How to Reproduce? 1. On a branch-4.0 cluster, run: ```sql CREATE TABLE compression_kind_repro (id INT) DUPLICATE KEY(id) DISTRIBUTED BY HASH(id) BUCKETS 1 PROPERTIES ("compression" = "zstd"); SHOW TABLETS FROM compression_kind_repro; SELECT TABLET_ID, COMPRESS_KIND FROM information_schema.backend_tablets WHERE TABLET_ID = <tablet_id_from_show_tablets>; ``` 2. Observe `COMPRESS_LZ4` in the system table, although the table property requests ZSTD page compression. The source path above explains why the field is fixed to LZ4. ### Anything Else? Relevant code: - https://github.com/apache/doris/blob/branch-4.0/be/src/olap/tablet_meta.cpp - https://github.com/apache/doris/blob/branch-4.0/be/src/exec/schema_scanner/schema_tablets_scanner.cpp - https://github.com/apache/doris/blob/branch-4.0/be/src/olap/rowset/segment_v2/segment_writer.cpp Documentation: https://doris.apache.org/docs/4.x/table-design/column-compression/ and https://doris.apache.org/docs/4.x/admin-manual/system-tables/information_schema/backend_tablets/ ### Are you willing to submit PR? - [ ] Yes I am willing to submit a PR! ### Code of Conduct - [x] I agree to follow this project's [Code of Conduct](https://www.apache.org/foundation/policies/conduct) -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
