Tim Armstrong has posted comments on this change. ( http://gerrit.cloudera.org:8080/11565 )
Change subject: Optimize expression to collect NULLs count ...................................................................... Patch Set 1: (1 comment) http://gerrit.cloudera.org:8080/#/c/11565/1/fe/src/main/java/org/apache/impala/analysis/ComputeStatsStmt.java File fe/src/main/java/org/apache/impala/analysis/ComputeStatsStmt.java: http://gerrit.cloudera.org:8080/#/c/11565/1/fe/src/main/java/org/apache/impala/analysis/ComputeStatsStmt.java@250 PS1, Line 250: columnStatsSelectList.add("COUNT(*) - COUNT(" + colRefSql + ")"); It's not obvious to me that this should be faster after we do code generation since the generated code for the case statement should be basically the same as for counting non-null values except with the condition inverted. Have you done any experiments? -- To view, visit http://gerrit.cloudera.org:8080/11565 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: Ic68f8b4c3756eb1980ce299a602a7d56db1e507a Gerrit-Change-Number: 11565 Gerrit-PatchSet: 1 Gerrit-Owner: [email protected] Gerrit-Reviewer: Impala Public Jenkins <[email protected]> Gerrit-Reviewer: Tim Armstrong <[email protected]> Gerrit-Comment-Date: Tue, 02 Oct 2018 20:59:19 +0000 Gerrit-HasComments: Yes
