xinyiZzz opened a new pull request, #19338: URL: https://github.com/apache/doris/pull/19338
# Proposed changes Issue Number: close #xxx ## Problem summary session variable `scanner_once_block_num` support the maximum number of blocks returned by each scanning. Instead of maximum number of data rows returned by each scanning thread in a single execution. In some scenarios, modify `scanner_once_block_num` which will be faster and use less memory. The default `scanner_once_block_num=5`, which is the same behavior as the previous `doris_scanner_row_num=16384`. For large and wide table queries with 800 columns, adjust `scanner_once_block_num=1`, the time-cost is from 0.6s -> 0.4s, and the memory is only used by 40% of the previous one. ``` select * from tbl where str1="" and str2="" and str3="" ``` ## Checklist(Required) * [ ] Does it affect the original behavior * [ ] Has unit tests been added * [ ] Has document been added or modified * [ ] Does it need to update dependencies * [ ] Is this PR support rollback (If NO, please explain WHY) ## Further comments If this is a relatively large or complex change, kick off the discussion at [d...@doris.apache.org](mailto:d...@doris.apache.org) by explaining why you chose the solution you did and what alternatives you considered, etc... -- 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: commits-unsubscr...@doris.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@doris.apache.org For additional commands, e-mail: commits-h...@doris.apache.org
