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Posted to issues@hive.apache.org by "Hive QA (Jira)" <ji...@apache.org> on 2019/11/19 19:47:00 UTC
[jira] [Commented] (HIVE-22513) Constant propagation of casted
column in filter ops can cause incorrect results
[ https://issues.apache.org/jira/browse/HIVE-22513?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16977791#comment-16977791 ]
Hive QA commented on HIVE-22513:
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|| Vote || Subsystem || Runtime || Comment ||
|| || || || {color:brown} Prechecks {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:green}+1{color} | {color:green} mvninstall {color} | {color:green} 9m 46s{color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green} 1m 7s{color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} checkstyle {color} | {color:green} 0m 46s{color} | {color:green} master passed {color} |
| {color:blue}0{color} | {color:blue} findbugs {color} | {color:blue} 4m 13s{color} | {color:blue} ql in master has 1539 extant Findbugs warnings. {color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green} 1m 6s{color} | {color:green} master passed {color} |
|| || || || {color:brown} Patch Compile Tests {color} ||
| {color:green}+1{color} | {color:green} mvninstall {color} | {color:green} 1m 30s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green} 1m 9s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} javac {color} | {color:green} 1m 9s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} checkstyle {color} | {color:green} 0m 41s{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} findbugs {color} | {color:green} 4m 25s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green} 1m 3s{color} | {color:green} the patch passed {color} |
|| || || || {color:brown} Other Tests {color} ||
| {color:green}+1{color} | {color:green} asflicense {color} | {color:green} 0m 15s{color} | {color:green} The patch does not generate ASF License warnings. {color} |
| {color:black}{color} | {color:black} {color} | {color:black} 26m 32s{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 3.16.43-2+deb8u5 (2017-09-19) x86_64 GNU/Linux |
| Build tool | maven |
| Personality | /data/hiveptest/working/yetus_PreCommit-HIVE-Build-19498/dev-support/hive-personality.sh |
| git revision | master / 44697f0 |
| Default Java | 1.8.0_111 |
| findbugs | v3.0.1 |
| modules | C: ql U: ql |
| Console output | http://104.198.109.242/logs//PreCommit-HIVE-Build-19498/yetus.txt |
| Powered by | Apache Yetus http://yetus.apache.org |
This message was automatically generated.
> Constant propagation of casted column in filter ops can cause incorrect results
> -------------------------------------------------------------------------------
>
> Key: HIVE-22513
> URL: https://issues.apache.org/jira/browse/HIVE-22513
> Project: Hive
> Issue Type: Bug
> Reporter: Ádám Szita
> Assignee: Ádám Szita
> Priority: Major
> Attachments: HIVE-22513.0.patch
>
>
> This issue happens if CBO is disabled.
> We should not be propagating constants if the corresponding ExprNodeColumnDesc instance is wrapped inside a CAST operator as casting might truncate information from the original column.
> This can happen if we're using CAST in a WHERE clause, which will cause the projected columns to be replaced in a SELECT operator. Their new value will be the result of casting which could be a different value compared to that in the original column:
> {code:java}
> set hive.cbo.enable=false;
> set hive.fetch.task.conversion=more; --just for testing convenience
> create table testtb (id string);
> insert into testtb values('2019-11-05 01:01:11');
> select id, CAST(id AS VARCHAR(10)) from testtb where CAST(id AS VARCHAR(9)) = '2019-11-0';
> +------------+------------+
> | id | _c1 |
> +------------+------------+
> | 2019-11-0 | 2019-11-0 |
> +------------+------------+
> 1 row selected (0.168 seconds)
> -- VS expected: 2019-11-05 01:01:11 | 2019-11-05 {code}
> As to what types of casting (from and where types) cause information loss it's hard to properly keep track of, and I don't think it should be taken into consideration when deciding whether or not to propagate a constant. Rather than adding a big and potentially convoluted and fragile check for this, I propose to prevent constant mappings to be spawned out of CASTed columns.
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