Bharath Vissapragada has posted comments on this change. ( http://gerrit.cloudera.org:8080/11206 )
Change subject: IMPALA-5937: [DOCS] Documented enable_expr_rewrites query option ...................................................................... Patch Set 2: (3 comments) http://gerrit.cloudera.org:8080/#/c/11206/2/docs/topics/impala_enable_expr_rewrites.xml File docs/topics/impala_enable_expr_rewrites.xml: http://gerrit.cloudera.org:8080/#/c/11206/2/docs/topics/impala_enable_expr_rewrites.xml@37 PS2, Line 37: impala28 Does this mean these are in Impala 2.8.0. Please refer to my comment below. http://gerrit.cloudera.org:8080/#/c/11206/2/docs/topics/impala_enable_expr_rewrites.xml@39 PS2, Line 39: These optimizations walk through the expression trees and : rewrite them if they have constants that can be evaluated during query : analysis and replace them with evaluated expressions, removing the need to : evaluate them during runtime They don't always need to be constants. For ex: this [1] just walks through the tree and rewrites it to a different form. Constant folding is just one of the optimizations. May be clarify that? [1] https://github.com/apache/impala/commit/0aeb68050b3bc16b8a10a5a3ae65428e7edd9df5 http://gerrit.cloudera.org:8080/#/c/11206/2/docs/topics/impala_enable_expr_rewrites.xml@48 PS2, Line 48: impala29 This has improved over time. For ex: constant folding (IMPALA-1788) and Extract common conjuncts from disjunctions (IMPALA-1286) were added in 2.8.0 whereas "Simplify conditionals with constant conditions (IMPALA-1861)" was in 2.9.0. All of these are controlled with this switch. Do we need to update this doc to reflect this? -- To view, visit http://gerrit.cloudera.org:8080/11206 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: I82a27172a6a6570f9c3cebe1a516a29c755e6d58 Gerrit-Change-Number: 11206 Gerrit-PatchSet: 2 Gerrit-Owner: Alex Rodoni <[email protected]> Gerrit-Reviewer: Alex Rodoni <[email protected]> Gerrit-Reviewer: Bharath Vissapragada <[email protected]> Gerrit-Reviewer: Impala Public Jenkins <[email protected]> Gerrit-Reviewer: Lars Volker <[email protected]> Gerrit-Comment-Date: Tue, 14 Aug 2018 02:32:25 +0000 Gerrit-HasComments: Yes
