[
https://issues.apache.org/jira/browse/CASSANDRA-15803?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17715740#comment-17715740
]
Stefan Miklosovic commented on CASSANDRA-15803:
-----------------------------------------------
When it comes to a practical usage, when we have dozens of tables, how would a
guardrail look like? We can have tables for which allowing the filtering within
a partition is OK because we "know" that there is not going to be a lot of rows
within a partition so we are safe to assume that it would be quick. So, for
some tables it would be ok, for some it would not. Unless we model a guardrail
to be able to make a difference, per table, I would go with WITHIN PARTITION.
I would go with a guardrail only if we do not want to make it granular per
table.
[~jeromatron] [~adelapena] what do you think?
> Separate out allow filtering scanning through a partition versus scanning
> over the table
> ----------------------------------------------------------------------------------------
>
> Key: CASSANDRA-15803
> URL: https://issues.apache.org/jira/browse/CASSANDRA-15803
> Project: Cassandra
> Issue Type: Improvement
> Components: CQL/Syntax
> Reporter: Jeremy Hanna
> Assignee: Stefan Miklosovic
> Priority: Normal
>
> Currently allow filtering can mean two things in the spirit of "avoid
> operations that don't seek to a specific row or sequential rows of data."
> First, it can mean scanning across the entire table to meet the criteria of
> the query. That's almost always a bad thing and should be discouraged or
> disabled (see CASSANDRA-8303). Second, it can mean filtering within a
> specific partition. For example, in a query you could specify the full
> partition key and if you specify a criterion on a non-key field, it requires
> allow filtering.
> The second reason to require allow filtering is significantly less work to
> scan through a partition. It is still extra work over seeking to a specific
> row and getting N sequential rows though. So while an application developer
> and/or operator needs to be cautious about this second type, it's not
> necessarily a bad thing, depending on the table and the use case.
> I propose that we separate the way to specify allow filtering across an
> entire table from specifying allow filtering across a partition in a
> backwards compatible way. One idea that was brought up in Slack in the
> cassandra-dev room was to have allow filtering mean the superset - scanning
> across the table. Then if you want to specify that you *only* want to scan
> within a partition you would use something like
> {{ALLOW FILTERING [WITHIN PARTITION]}}
> So it will succeed if you specify non-key criteria within a single partition,
> but fail with a message to say it requires the full allow filtering. This
> would allow for a backwards compatible full allow filtering while allowing a
> user to specify that they want to just scan within a partition, but error out
> if trying to scan a full table.
> This is potentially also related to the capability limitation framework by
> which operators could more granularly specify what features are allowed or
> disallowed per user, discussed in CASSANDRA-8303. This way an operator could
> disallow the more general allow filtering while allowing the partition scan
> (or disallow them both at their discretion).
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
