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https://issues.apache.org/jira/browse/PHOENIX-6141?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kadir Ozdemir updated PHOENIX-6141:
-----------------------------------
    Fix Version/s: 5.2.0
                   5.1.4
                       (was: 4.17.0)

> Ensure consistency between SYSTEM.CATALOG and SYSTEM.CHILD_LINK
> ---------------------------------------------------------------
>
>                 Key: PHOENIX-6141
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-6141
>             Project: Phoenix
>          Issue Type: Improvement
>    Affects Versions: 5.0.0, 4.15.0
>            Reporter: Chinmay Kulkarni
>            Assignee: Palash Chauhan
>            Priority: Blocker
>             Fix For: 5.2.0, 5.1.4
>
>
> Before 4.15, "CREATE/DROP VIEW" was an atomic operation since we were issuing 
> batch mutations on just the 1 SYSTEM.CATALOG region. In 4.15 we introduced 
> SYSTEM.CHILD_LINK to store the parent->child links and so a CREATE VIEW is no 
> longer atomic since it consists of 2 separate RPCs  (1 to SYSTEM.CHILD_LINK 
> to add the linking row and another to SYSTEM.CATALOG to write metadata for 
> the new view). 
> If the second RPC i.e. the RPC to write metadata to SYSTEM.CATALOG fails 
> after the 1st RPC has already gone through, there will be an inconsistency 
> between both metadata tables. We will see orphan parent->child linking rows 
> in SYSTEM.CHILD_LINK in this case. This can cause the following issues:
> # ALTER TABLE calls on the base table will fail
> # DROP TABLE without CASCADE will fail
> # The upgrade path has calls like UpgradeUtil.upgradeTable() which will fail
> # Any metadata consistency checks can be thrown off
> # Unnecessary extra storage of orphan links
> The first 3 issues happen because we wrongly deduce that a base table has 
> child views due to the orphan linking rows.
> This Jira aims at trying to come up with a way to make mutations among 
> SYSTEM.CATALOG and SYSTEM.CHILD_LINK an atomic transaction. We can use a 
> 2-phase commit approach like in global indexing or also potentially explore 
> using a transaction manager. 



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