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From "Hive QA (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-20536) Add Surrogate Keys function to Hive
Date Wed, 19 Sep 2018 02:57:00 GMT

    [ https://issues.apache.org/jira/browse/HIVE-20536?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16620011#comment-16620011
] 

Hive QA commented on HIVE-20536:
--------------------------------

| (x) *{color:red}-1 overall{color}* |
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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}  8m 53s{color}
| {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green}  1m  6s{color} |
{color:green} master passed {color} |
| {color:green}+1{color} | {color:green} checkstyle {color} | {color:green}  0m 44s{color}
| {color:green} master passed {color} |
| {color:blue}0{color} | {color:blue} findbugs {color} | {color:blue}  4m  9s{color} | {color:blue}
ql in master has 2326 extant Findbugs warnings. {color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green}  1m  0s{color} |
{color:green} master passed {color} |
|| || || || {color:brown} Patch Compile Tests {color} ||
| {color:green}+1{color} | {color:green} mvninstall {color} | {color:green}  1m 26s{color}
| {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green}  1m  5s{color} |
{color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} javac {color} | {color:green}  1m  5s{color} | {color:green}
the patch passed {color} |
| {color:red}-1{color} | {color:red} checkstyle {color} | {color:red}  0m 45s{color} | {color:red}
ql: The patch generated 1 new + 640 unchanged - 0 fixed = 641 total (was 640) {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 18s{color} |
{color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green}  1m  1s{color} |
{color:green} the patch passed {color} |
|| || || || {color:brown} Other Tests {color} ||
| {color:green}+1{color} | {color:green} asflicense {color} | {color:green}  0m 13s{color}
| {color:green} The patch does not generate ASF License warnings. {color} |
| {color:black}{color} | {color:black} {color} | {color:black} 25m 14s{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_PreCommit-HIVE-Build-13894/dev-support/hive-personality.sh
|
| git revision | master / 9c90776 |
| Default Java | 1.8.0_111 |
| findbugs | v3.0.0 |
| checkstyle | http://104.198.109.242/logs//PreCommit-HIVE-Build-13894/yetus/diff-checkstyle-ql.txt
|
| modules | C: ql U: ql |
| Console output | http://104.198.109.242/logs//PreCommit-HIVE-Build-13894/yetus.txt |
| Powered by | Apache Yetus    http://yetus.apache.org |


This message was automatically generated.



> Add Surrogate Keys function to Hive
> -----------------------------------
>
>                 Key: HIVE-20536
>                 URL: https://issues.apache.org/jira/browse/HIVE-20536
>             Project: Hive
>          Issue Type: Task
>          Components: Hive
>            Reporter: Miklos Gergely
>            Assignee: Miklos Gergely
>            Priority: Major
>         Attachments: HIVE-20536.01.patch, HIVE-20536.02.patch, HIVE-20536.03.patch, HIVE-20536.04.patch,
HIVE-20536.05.patch, HIVE-20536.06.patch
>
>
> Surrogate keys is an ability to generate and use unique integers for each row in a table.
If we have that ability then in conjunction with default clause we can get surrogate keys
functionality. Consider following ddl:
> create table t1 (a string, b bigint default unique_long());
> We already have default clause wherein you can specify a function to provide values.
So, what we need is udf which can generate unique longs for each row across queries for a
table. 
> Idea is to use write_id . This is a column in metastore table TXN_COMPONENTS whose value
is determined at compile time to be used during query execution. Each query execution generates
a new write_id. So, we can seed udf with this value during compilation.
> Then we statically allocate ranges for each task from which it can draw next long. So,
lets say 64-bit write_id we divy up such that last 24 bits belong to original usage of it
that is txns. Next 16 bits are used for task_attempts and last 24 bits to generate new long
for each row. This implies we can allow 17M txns, 65K tasks and 17M rows in a task. If you
hit any of those limits we can fail the query.
> Implementation wise: serialize write_id in initialize() of udf. Then during execute()
we find out what task_attempt current task is and use it along with write_id() to get starting
long and give a new value on each invocation of execute().
> Here we are assuming write_id can be determined at compile time, which should be the
case but we need to figure out how to get handle to it.



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