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https://issues.apache.org/jira/browse/CASSANDRA-18217?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17716806#comment-17716806
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Andres de la Peña commented on CASSANDRA-18217:
-----------------------------------------------
Here is a patch removing the need of using {{ALLOW FILTERING}} when all the
filtering expressions are supported by a single index group:
||PR||CI||
|[16052|https://github.com/maedhroz/cassandra/pull/11]|[j8|https://app.circleci.com/pipelines/github/adelapena/cassandra/2872/workflows/6b028cb0-214d-49a3-867a-cb9485155f09]
[j11|https://app.circleci.com/pipelines/github/adelapena/cassandra/2872/workflows/1d9f147c-e387-43ea-80a9-2a493f0cb655]|
The approach consists on delegating most of the {{ALLOW FILTERING}} checks to a
series of {{needsFiltering}} methods on the restrictions, so they can find out
if is an index group able to process them.
Additionally to the number of queried columns, I have found that there is also
a requirement to use AF when there query has multiple contains expressions,
even if they are for the same column. For example:
{code:java}
CREATE TABLE %s (pk int primary key, value map<int, text>);
CREATE CUSTOM INDEX ON %s(ENTRIES(value)) USING 'StorageAttachedIndex';
SELECT * FROM %s WHERE value[1] = 'v1' AND value[2] = 'v2' ALLOW FILTERING;
{code}
I think that makes sense for legacy indexes, where we can only efficiently
query a single value. However, SAI doesn't seem to perform filtering in that
case, so IUC it shouldn't require {{{}ALLOW FILTERING{}}}. So I have added a
new {{Index#filtersMultipleContains}} method to define whether the index
implementation is able to process multiple contains without filtering.
I have also eliminated all the now unneeded uses of {{ALLOW FILTERING}} that I
have found on the tests. In order to reduce the risk of missing something, I
have extended {{IndexQuerySupport.BaseQuerySet#validate}} to verify that any
query supplied with AF really needs it.
> Allow CQL queries on multiple indexes without ALLOW FILTERING
> -------------------------------------------------------------
>
> Key: CASSANDRA-18217
> URL: https://issues.apache.org/jira/browse/CASSANDRA-18217
> Project: Cassandra
> Issue Type: Improvement
> Components: Feature/SAI
> Reporter: Mike Adamson
> Assignee: Andres de la Peña
> Priority: Normal
> Labels: SAI
>
> The Index Group index was added by
> [CASSANDRA-16092|https://issues.apache.org/jira/browse/CASSANDRA-16092] to
> allow indexes to be grouped and have more than one index expression in a
> query. This did not make any changes to StatementRestrictions so CQL queries
> using multiple index expression still need to add ALLOW FILTERING to the
> query to be valid.
> This restriction should be removed such that any number of index expressions
> can be used on a CQL query without needing ALLOW FILTERING.
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