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Posted to commits@cassandra.apache.org by "Benjamin Lerer (Jira)" <ji...@apache.org> on 2022/02/15 10:35:00 UTC
[jira] [Comment Edited] (CASSANDRA-17198) Allow to filter using LIKE predicates
[ https://issues.apache.org/jira/browse/CASSANDRA-17198?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17492515#comment-17492515 ]
Benjamin Lerer edited comment on CASSANDRA-17198 at 2/15/22, 10:34 AM:
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[~subkanthi] Looking at the patch there are several point that would need to be changed.
* Without indexes LIKE restrictions can only be performed through filtering. That means that the queries should fail if {{ALLOW FILTERING}} is not specified. As shown by some of the unit tests it is not the case. This should be changed for clustering columns by modifying {{StatementRestrictions.processClusteringColumnRestrictions}} and for the partition keys by modifying {{PartitionKeySingleRestrictionSet.needFiltering}}. For that last one you will need to add a new {{hasLike}} method to {{Restrictions}} and use it.
* If the user attempt to use a LIKE restriction on a column which is not a string type the error can be confusing. The logic within {{SingleColumnRelation.newLikeRestriction}} can be changed to validate that the type of the receiver (for a LIKE you are guaranty to have only one) is a instanceof StringType.
* It should be good to test that LIKE statement cannot be used on UPDATE or DELETE statements.
was (Author: blerer):
[~subkanthi] Looking at the patch there are several point that would need to be changed.
* Without indexes LIKE restrictions can only be performed through filtering. That means that the queries should fail if {{ALLOW FILTERING}} is not specified. As shown by some of the unit tests it is not the case. This should be changed for clustering columns by modifying {{StatementRestrictions.processClusteringColumnRestrictions}} and for the partition keys by modifying {{PartitionKeySingleRestrictionSet.needFiltering}}. For that last one you will need to add a new {{hasLike}} method to {{Restrictions}} and use it.
* If the user attempt to use a LIKE restriction on a column which is not a string type the error can be confusing. The logic within {{SingleColumnRelation.newLikeRestriction}} can be changed to validate that the type of the receiver (for a LIKE you are guaranty to have only one) is a instanceof StringType.
> Allow to filter using LIKE predicates
> -------------------------------------
>
> Key: CASSANDRA-17198
> URL: https://issues.apache.org/jira/browse/CASSANDRA-17198
> Project: Cassandra
> Issue Type: Improvement
> Components: CQL/Syntax
> Reporter: Benjamin Lerer
> Assignee: Kanthi Subramanian
> Priority: Normal
> Labels: AdventCalendar2021, lhf
> Fix For: 4.x
>
>
> {{LIKE}} predicates can only be used with the SASI indices. In several usecases (e.g. querying the {{settings}} virtual table) it makes sense to support them for filtering.
> +Additional information for newcomers:+
> There are some checks in the {{StatementRestrictions}} constructor and on {{LikeRestriction}} that need to be removed for allowing filtering using LIKE on clustering and regular columns.
> For filtering on partition columns the {{needFiltering}} methods in {{PartitionKeySingleRestrictionSet}} will need to be modified to return true when LIKE predicate are used.
> The unit tests should go in {{SelectTest}}.
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