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ASF GitHub Bot logged work on HIVE-23006: ----------------------------------------- Author: ASF GitHub Bot Created on: 03/Apr/20 02:53 Start Date: 03/Apr/20 02:53 Worklog Time Spent: 10m Work Description: jcamachor commented on issue #952: HIVE-23006 ProbeDecode compiler support URL: https://github.com/apache/hive/pull/952#issuecomment-608201286 @pgaref , thanks for changes. Patch looks good. About the name, I think it is fine (probe side for the filtering generated statically in case of expressions or dynamically for joins). I think main remaining issue is related to selection in case of multiple MJ operators. I was thinking that for the time being, we could make the policy pluggable via config and have three very simple ones: 1) keep all of them, 2) keep the one with lowest `ndv_JOIN_key_column / ndv_TS_target_column` ratio, or 3) keep those with ratio below a certain threshold specified through a config value. Alternatively, in this patch you could maybe go only with option 2 and tackle others in follow-up. You have the information about the stats in the operators themselves (follow `op.getStatistics()` calls to see how it is retrieved per column basis). Thus, I would make that decision in the TezCompiler (once we gather all the context information) rather than GenTezUtils. ---------------------------------------------------------------- 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. For queries about this service, please contact Infrastructure at: us...@infra.apache.org Issue Time Tracking ------------------- Worklog Id: (was: 415293) Time Spent: 40m (was: 0.5h) > Compiler support for Probe MapJoin > ---------------------------------- > > Key: HIVE-23006 > URL: https://issues.apache.org/jira/browse/HIVE-23006 > Project: Hive > Issue Type: Sub-task > Reporter: Panagiotis Garefalakis > Assignee: Panagiotis Garefalakis > Priority: Major > Labels: pull-request-available > Time Spent: 40m > Remaining Estimate: 0h > > The decision of pushing down information to the Record reader (potentially > reducing decoding time by row-level filtering) should be done at query > compilation time. > This patch adds an extra optimisation step with the goal of finding Table > Scan operators that could reduce the number of rows decoded at runtime using > extra available information. > It currently looks for all the available MapJoin operators that could use the > smaller HashTable on the probing side (where TS is) to filter-out rows that > would never match. > To do so the HashTable information is pushed down to the TS properties and > then propagated as part of MapWork. > If the a single TS is used by multiple operators (shared-word), this rule can > not be applied. > This rule can be extended to support static filter expressions like: > _select * from sales where sold_state = 'PR';_ > This optimisation manly targets the Tez execution engine running on Llap. -- This message was sent by Atlassian Jira (v8.3.4#803005)