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From "Edward Capriolo (JIRA)" <>
Subject [jira] Commented: (HIVE-1841) datanucleus.fixedDatastore should be true in hive-default.xml
Date Wed, 08 Dec 2010 19:29:00 GMT


Edward Capriolo commented on HIVE-1841:


I agree with
But datanucleus.fixedDatastore is not specified and it defaults to true. This causes and auto-upgrade
which could be dangerous. I believe we should set datanucleus.fixedDatastore to true, or at
very least document it in hive-default.xml. 

I say this because my first assumption was if i build a hive from trunk and point it at a
production metastore, run some select queries for QA, it could "do no harm". However since
datanucleus.fixedDatastore is true as soon as a client touches the metastore it will make
any changes it feels are appropriate. In the future imagine and old hive install laying around,
what if an old hive 0.4.0 instances points at an hive 0.9.0 metastore if could try to add
something that has since been removed, or worse.

>  datanucleus.fixedDatastore should be true in hive-default.xml
> --------------------------------------------------------------
>                 Key: HIVE-1841
>                 URL:
>             Project: Hive
>          Issue Type: Improvement
>          Components: Configuration
>    Affects Versions: 0.6.0
>            Reporter: Edward Capriolo
>             Fix For: 0.7.0
> Two datanucleus variables:
> {noformat}
> <property>
>  <name>datanucleus.autoCreateSchema</name>
>  <value>false</value>
> </property>
> <property>
>  <name>datanucleus.fixedDatastore</name>
>  <value>true</value>
> </property>
> {noformat}
> are dangerous.  We do want the schema to auto-create itself, but we do not want the schema
to auto update itself. 
> Someone might accidentally point a trunk at the wrong meta-store and unknowingly update.
I believe we should set this to false and possibly trap exceptions stemming from hive wanting
to do any update. This way someone has to actively acknowledge the update, by setting this
to true and then starting up hive, or leaving it false, removing schema modifies for the user
that hive usages, and doing all the time and doing the updates by hand. 

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