[
https://issues.apache.org/jira/browse/BEAM-9008?focusedWorklogId=415903&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-415903
]
ASF GitHub Bot logged work on BEAM-9008:
----------------------------------------
Author: ASF GitHub Bot
Created on: 04/Apr/20 02:26
Start Date: 04/Apr/20 02:26
Worklog Time Spent: 10m
Work Description: vmarquez commented on issue #10546: [BEAM-9008] Add
CassandraIO readAll method
URL: https://github.com/apache/beam/pull/10546#issuecomment-607043571
Hi @iemejia I've been busy with work and life but was finally able to this
just about finished up! To get around the connection issue (not caching the
connection was causing the Cassandra tests to run for ~ten minutes!), by
passing in a ReadAll<T> to the ReadFn, we're able to initiate a connection in
the setup method, but we can still 'dynamically' use the passed in Read<T> to
generate specific queries or query ranges.
As for a more advanced connection pooling, I'd prefer to get this merged in
and then perhaps work on an additional PR.
----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
For queries about this service, please contact Infrastructure at:
us...@infra.apache.org
Issue Time Tracking
-------------------
Worklog Id: (was: 415903)
Time Spent: 5h 40m (was: 5.5h)
> Add readAll() method to CassandraIO
> -----------------------------------
>
> Key: BEAM-9008
> URL: https://issues.apache.org/jira/browse/BEAM-9008
> Project: Beam
> Issue Type: New Feature
> Components: io-java-cassandra
> Affects Versions: 2.16.0
> Reporter: vincent marquez
> Assignee: vincent marquez
> Priority: Minor
> Fix For: 2.21.0
>
> Time Spent: 5h 40m
> Remaining Estimate: 0h
>
> When querying a large cassandra database, it's often *much* more useful to
> programatically generate the queries needed to to be run rather than reading
> all partitions and attempting some filtering.
> As an example:
> {code:java}
> public class Event {
> @PartitionKey(0) public UUID accountId;
> @PartitionKey(1)public String yearMonthDay;
> @ClusteringKey public UUID eventId;
> //other data...
> }{code}
> If there is ten years worth of data, you may want to only query one year's
> worth. Here each token range would represent one 'token' but all events for
> the day.
> {code:java}
> Set<UUID> accounts = getRelevantAccounts();
> Set<String> dateRange = generateDateRange("2018-01-01", "2019-01-01");
> PCollection<TokenRange> tokens = generateTokens(accounts, dateRange);
> {code}
>
> I propose an additional _readAll()_ PTransform that can take a PCollection
> of token ranges and can return a PCollection<T> of what the query would
> return.
> *Question: How much code should be in common between both methods?*
> Currently the read connector already groups all partitions into a List of
> Token Ranges, so it would be simple to refactor the current read() based
> method to a 'ParDo' based one and have them both share the same function.
> Reasons against sharing code between read and readAll
> * Not having the read based method return a BoundedSource connector would
> mean losing the ability to know the size of the data returned
> * Currently the CassandraReader executes all the grouped TokenRange queries
> *asynchronously* which is (maybe?) fine when all that's happening is
> splitting up all the partition ranges but terrible for executing potentially
> millions of queries.
> Reasons _for_ sharing code would be simplified code base and that both of
> the above issues would most likely have a negligable performance impact.
>
>
>
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
