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https://issues.apache.org/jira/browse/HIVE-22163?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16938172#comment-16938172
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Vineet Garg commented on HIVE-22163:
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+1 LGTM
> CBO: Enabling CBO turns on stats estimation, even when the estimation is
> disabled
> ---------------------------------------------------------------------------------
>
> Key: HIVE-22163
> URL: https://issues.apache.org/jira/browse/HIVE-22163
> Project: Hive
> Issue Type: Bug
> Components: CBO
> Reporter: Gopal Vijayaraghavan
> Assignee: Krisztian Kasa
> Priority: Major
> Attachments: HIVE-22163.1.patch, HIVE-22163.1.patch,
> HIVE-22163.1.patch, HIVE-22163.2.patch, HIVE-22163.3.patch,
> HIVE-22163.4.patch, HIVE-22163.4.patch, HIVE-22163.5.patch,
> HIVE-22163.5.patch, HIVE-22163.5.patch, HIVE-22163.5.patch,
> HIVE-22163.5.patch, HIVE-22163.5.patch, HIVE-22163.5.patch
>
>
> {code}
> create table claims(claim_rec_id bigint, claim_invoice_num string, typ_c int);
> alter table claims update statistics set
> ('numRows'='1154941534','rawDataSize'='1135307527922');
> set hive.stats.estimate=false;
> explain extended select count(1) from claims where typ_c=3;
> set hive.stats.ndv.estimate.percent=5e-7;
> explain extended select count(1) from claims where typ_c=3;
> {code}
> Expecting the standard /2 for the single filter, but we instead get 5 rows.
> {code}
> ' Map Operator Tree:'
> ' TableScan'
> ' alias: claims'
> ' filterExpr: (typ_c = 3) (type: boolean)'
> ' Statistics: Num rows: 1154941534 Data size: 4388777832
> Basic stats: COMPLETE Column stats: NONE'
> ' GatherStats: false'
> ' Filter Operator'
> ' isSamplingPred: false'
> ' predicate: (typ_c = 3) (type: boolean)'
> ' Statistics: Num rows: 5 Data size: 19 Basic stats:
> COMPLETE Column stats: NONE'
> {code}
> The estimation is in effect, as changing the estimate.percent changes this.
> {code}
> ' filterExpr: (typ_c = 3) (type: boolean)'
> ' Statistics: Num rows: 1154941534 Data size: 4388777832
> Basic stats: COMPLETE Column stats: NONE'
> ' GatherStats: false'
> ' Filter Operator'
> ' isSamplingPred: false'
> ' predicate: (typ_c = 3) (type: boolean)'
> ' Statistics: Num rows: 230988307 Data size: 877755567
> Basic stats: COMPLETE Column stats: NONE'
> {code}
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