[ https://issues.apache.org/jira/browse/HIVE-18108?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Zoltan Haindrich updated HIVE-18108: ------------------------------------ Attachment: HIVE-18108.03.patch > in case basic stats are missing; rowcount estimation depends on the selected > columns size > ----------------------------------------------------------------------------------------- > > Key: HIVE-18108 > URL: https://issues.apache.org/jira/browse/HIVE-18108 > Project: Hive > Issue Type: Sub-task > Reporter: Zoltan Haindrich > Assignee: Zoltan Haindrich > Attachments: HIVE-18108.01.patch, HIVE-18108.02.patch, > HIVE-18108.02wip02.patch, HIVE-18108.03.patch > > > in case basicstats are not available (especially rowcount): > {code} > set hive.stats.autogather=false; > create table t (a integer, b string); > insert into t values (1,'asd1'); > insert into t values (2,'asd2'); > insert into t values (3,'asd3'); > insert into t values (4,'asd4'); > insert into t values (5,'asd5'); > explain select a,count(1) from t group by a; > -- estimated to read 8 rows from table t > explain select b,count(1) from t group by b; > -- estimated: 1 rows > explain select a,b,count(1) from t group by a,b; > -- estimated: 1 rows > {code} > it may not depend on the actually selected column set. -- This message was sent by Atlassian JIRA (v6.4.14#64029)