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https://issues.apache.org/jira/browse/PHOENIX-6141?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17754284#comment-17754284
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ASF GitHub Bot commented on PHOENIX-6141:
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palashc opened a new pull request, #1655:
URL: https://github.com/apache/phoenix/pull/1655
…SYSTEM.CHILD_LINK (#1575)"
This reverts commit 61180892c2f71f5e7eb2956c0e226cd03dda48f1.
As reported in
[PHOENIX-7017](https://issues.apache.org/jira/browse/PHOENIX-7017), this change
introduced a bug in CREATE VIEW where the child link metadata is deleted if the
same view is created again on the same parent. The read repair implementation
also does not ensure that the parent-child link is not overwritten with a new
timestamp when creating same view on same parent.
We will rethink how to implement
[PHOENIX-6141](https://issues.apache.org/jira/browse/PHOENIX-6141) using the
current indexing framework.
> 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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