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Posted to issues@ignite.apache.org by "Ivan Pavlukhin (JIRA)" <ji...@apache.org> on 2019/02/04 13:49:00 UTC
[jira] [Comment Edited] (IGNITE-8841) MVCC TX: Read transactions
remap when coordinator fails.
[ https://issues.apache.org/jira/browse/IGNITE-8841?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16759857#comment-16759857 ]
Ivan Pavlukhin edited comment on IGNITE-8841 at 2/4/19 1:48 PM:
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[~gvvinblade] please find my comments below.
# Can we get rid of {{MvccUtils.requestSnapshot}} as it mostly delegates to {{GridNearTxLocal}}?
# I did not get why do we need to call {{PreviousQueries.init}} from {{onLocalJoin}} callback? It worth adding a comment explaining the idea.
was (Author: pavlukhin):
[~gvvinblade] please find my comments below.
# Can we get rid of {{MvccUtils.requestSnapshot as it mostly delegates to {{GridNearTxLocal}}?
# I did not get why do we need to call {{PreviousQueries.init}} from {{onLocalJoin}} callback? It worth adding a comment explaining the idea.
> MVCC TX: Read transactions remap when coordinator fails.
> --------------------------------------------------------
>
> Key: IGNITE-8841
> URL: https://issues.apache.org/jira/browse/IGNITE-8841
> Project: Ignite
> Issue Type: Bug
> Components: mvcc, sql
> Reporter: Roman Kondakov
> Assignee: Igor Seliverstov
> Priority: Major
> Labels: failover
> Time Spent: 50m
> Remaining Estimate: 0h
>
> At the moment read transactions that don't acquire topology lock will be forcibly rolled back on topology change as read tx can be in fly while topology being change.
> This is done to prevent having active transaction with stale snapshots on new topology in cases of TX coordinator or Near node were lost.
>
> It would be nice to remap it somehow until they locked a topology or at least throw some meaningful exception to user.
> For example, it is possible to obtain a new "write" mvcc version from the new coordinator and use this version for all further writes while using "old" version for reads. In this case we need to change visibility rules a little: "old" version should see "own" updates made by "new" "write" version.
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