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https://issues.apache.org/jira/browse/CASSANDRA-18519?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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David Capwell updated CASSANDRA-18519:
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Reviewers: Ariel Weisberg
Status: Review In Progress (was: Patch Available)
> CEP-15: (C*) Add notion of CommandsForRanges and make this durable in C*
> ------------------------------------------------------------------------
>
> Key: CASSANDRA-18519
> URL: https://issues.apache.org/jira/browse/CASSANDRA-18519
> Project: Cassandra
> Issue Type: Task
> Components: Accord
> Reporter: David Capwell
> Assignee: David Capwell
> Priority: Normal
> Labels: pull-request-available
> Fix For: 5.x
>
> Time Spent: 2h 50m
> Remaining Estimate: 0h
>
> To add support for range transactions in C* we need to make sure
> 1) their state is durable and can be recovered on restart
> 2) have some way to find all CommandsForKey that are contained in the range
> transaction range
> 3) have some way to find all CommandsForRange that intersect this range
> To do this, I propose the following
> 1) Create a new commands_for_range table that stores: (store, range) ->
> list<accord_timestamp_tuple> — this is byId, not sure if repair needs
> byExecuteId as well
> 2) For C*, store a in-memory mapping of Range -> List<TxnId>, and on-boot
> repopulate this cache. This then can be used to construct the
> CommandsForRange needed by the transaction. This makes an assumption that
> many ranges will not exist, at least for the time being.
> 3) Change commands_for_keys to use LocalPartitioner, and order the table by
> (store, key)
> 4) When C* sees a range transaction, find all keys that are contained by the
> range by running the logical query "SELECT key FROM commands_for_keys WHERE
> key BETWEEN range.start AND range.end". Implementation has to make sure to
> handle many keys (may need to partition the range to increase parallel
> access, and may need to page through the table to see all keys (aka multiple
> ReadCommands)). Once all keys are found, then must load into the
> CommandsForKeys cache
> For #4, https://github.com/apache/cassandra-accord/pull/27 maybe able to
> optimize the logic to lazy load only what is actually needed rather than load
> the whole world
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