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Posted to issues@hive.apache.org by "Hive QA (JIRA)" <ji...@apache.org> on 2017/12/05 12:25:00 UTC
[jira] [Commented] (HIVE-18149) Stats: rownum estimation from
datasize underestimates in most cases
[ https://issues.apache.org/jira/browse/HIVE-18149?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16278468#comment-16278468 ]
Hive QA commented on HIVE-18149:
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| (/) *{color:green}+1 overall{color}* |
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|| Vote || Subsystem || Runtime || Comment ||
|| || || || {color:brown} Prechecks {color} ||
| {color:blue}0{color} | {color:blue} findbugs {color} | {color:blue} 0m 1s{color} | {color:blue} Findbugs executables are not available. {color} |
| {color:green}+1{color} | {color:green} @author {color} | {color:green} 0m 0s{color} | {color:green} The patch does not contain any @author tags. {color} |
|| || || || {color:brown} master Compile Tests {color} ||
| {color:blue}0{color} | {color:blue} mvndep {color} | {color:blue} 0m 56s{color} | {color:blue} Maven dependency ordering for branch {color} |
| {color:green}+1{color} | {color:green} mvninstall {color} | {color:green} 5m 45s{color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green} 1m 15s{color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} checkstyle {color} | {color:green} 0m 50s{color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green} 1m 5s{color} | {color:green} master passed {color} |
|| || || || {color:brown} Patch Compile Tests {color} ||
| {color:blue}0{color} | {color:blue} mvndep {color} | {color:blue} 0m 20s{color} | {color:blue} Maven dependency ordering for patch {color} |
| {color:green}+1{color} | {color:green} mvninstall {color} | {color:green} 1m 33s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green} 1m 20s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} javac {color} | {color:green} 1m 20s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} checkstyle {color} | {color:green} 0m 47s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} whitespace {color} | {color:green} 0m 0s{color} | {color:green} The patch has no whitespace issues. {color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green} 1m 7s{color} | {color:green} the patch passed {color} |
|| || || || {color:brown} Other Tests {color} ||
| {color:green}+1{color} | {color:green} asflicense {color} | {color:green} 0m 12s{color} | {color:green} The patch does not generate ASF License warnings. {color} |
| {color:black}{color} | {color:black} {color} | {color:black} 15m 28s{color} | {color:black} {color} |
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|| Subsystem || Report/Notes ||
| Optional Tests | asflicense javac javadoc findbugs checkstyle compile |
| uname | Linux hiveptest-server-upstream 3.16.0-4-amd64 #1 SMP Debian 3.16.36-1+deb8u1 (2016-09-03) x86_64 GNU/Linux |
| Build tool | maven |
| Personality | /data/hiveptest/working/yetus/dev-support/hive-personality.sh |
| git revision | master / f631241 |
| Default Java | 1.8.0_111 |
| modules | C: common ql U: . |
| Console output | http://104.198.109.242/logs//PreCommit-HIVE-Build-8109/yetus.txt |
| Powered by | Apache Yetus http://yetus.apache.org |
This message was automatically generated.
> Stats: rownum estimation from datasize underestimates in most cases
> -------------------------------------------------------------------
>
> Key: HIVE-18149
> URL: https://issues.apache.org/jira/browse/HIVE-18149
> Project: Hive
> Issue Type: Sub-task
> Components: Statistics
> Reporter: Zoltan Haindrich
> Assignee: Zoltan Haindrich
> Attachments: HIVE-18149.01wip01.patch
>
>
> rownum estimation is based on the following fact as of now:
> * datasize being used from the following sources:
> ** basicstats aggregates the loaded "on-heap" row sizes ; other readers are able to give "raw size" estimation - I've checked orc; but I'm sure others will do the same....api docs are a bit vague about the methods purpose...
> ** if the basicstats level info is not available; the filesystem level "file-size-sums" are used as the "raw data size" ; which is multiplied by the [deserialization ratio|https://github.com/apache/hive/blob/d9924ab3e285536f7e2cc15ecbea36a78c59c66d/ql/src/java/org/apache/hadoop/hive/ql/stats/StatsUtils.java#L261] ; which is currently 1.
> the problem with all of this is that deser factor is 1; and that rowsize counts in the online object headers..
> example; 20 rows are loaded into a partition [columnstats_partlvl_dp.q|https://github.com/apache/hive/blob/d9924ab3e285536f7e2cc15ecbea36a78c59c66d/ql/src/test/queries/clientpositive/columnstats_partlvl_dp.q#L7]
> after HIVE-18108 [this explain|https://github.com/apache/hive/blob/d9924ab3e285536f7e2cc15ecbea36a78c59c66d/ql/src/test/queries/clientpositive/columnstats_partlvl_dp.q#L25] will estimate the rowsize of the table to be 404 bytes; however the 20 rows of text is only 169 bytes...so it ends up with 0 rows...
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