[jira] [Reopened] (CASSANDRA-6876) Improve PerRowSecondaryIndex performance by removing O(N) complexity when computing indexes for a column

["Sergio Bossa (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CASSANDRA-6876?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Sergio Bossa reopened CASSANDRA-6876:
-------------------------------------


Reopened, as removal of a field causes removal of the related secondary index from the "all indexes" map, even if such index is still used.

> Improve PerRowSecondaryIndex performance by removing O(N) complexity when computing indexes for a column
> --------------------------------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-6876
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6876
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Sergio Bossa
>            Assignee: Sergio Bossa
>            Priority: Minor
>             Fix For: 2.0.7, 2.1 beta2
>
>         Attachments: CASSANDRA-6876-2.patch, CASSANDRA-6876.2.1.patch, CASSANDRA-6876.patch
>
>
> Currently, given SecondaryIndexManager tracks all per-column and per-row secondary indexes in a by-column map, when computing indexes for a given column it has to scan all indexes for *all* columns, meaning that it will scan the *same* per-row index N times, where N is the number of columns it is associated with, raising the complexity of what could be an O(1) operation to O(N).



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