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https://issues.apache.org/jira/browse/TEPHRA-35?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15372470#comment-15372470
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James Taylor commented on TEPHRA-35:
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bq. At the time a transaction client starts a transaction, if it knows in
advance all the tables that will be used in the transaction (like in Phoenix's
case)
Phoenix doesn't know all of the tables involved at the start of a transaction.
It would at the end of the transaction, though (for example, during
canCommit()).
I think it's fine to do this in a phased approach, starting with having to wait
for all tables to major compact.
> Prune invalid transaction set once all data for a given invalid transaction
> has been dropped
> --------------------------------------------------------------------------------------------
>
> Key: TEPHRA-35
> URL: https://issues.apache.org/jira/browse/TEPHRA-35
> Project: Tephra
> Issue Type: New Feature
> Reporter: Gary Helmling
> Assignee: Poorna Chandra
> Priority: Blocker
> Attachments: ApacheTephraAutomaticInvalidListPruning-v2.pdf
>
>
> In addition to dropping the data from invalid transactions we need to be able
> to prune the invalid set of any transactions where data cleanup has been
> completely performed. Without this, the invalid set will grow indefinitely
> and become a greater and greater cost to in-progress transactions over time.
> To do this correctly, the TransactionDataJanitor coprocessor will need to
> maintain some bookkeeping for the transaction data that it removes, so that
> the transaction manager can reason about when all of a given transaction's
> data has been removed. Only at this point can the transaction manager safely
> drop the transaction ID from the invalid set.
> One approach would be for the TransactionDataJanitor to update a table
> marking when a major compaction was performed on a region and what
> transaction IDs were filtered out. Once all regions in a table containing the
> transaction data have been compacted, we can remove the filtered out
> transaction IDs from the invalid set. However, this will need to cope with
> changing region names due to splits, etc.
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