[jira] [Commented] (CASSANDRA-4694) populate_io_cache_on_flush option should be configurable for each column family independently

["Alexey Zotov (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-4694?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13461689#comment-13461689 ] 

Alexey Zotov commented on CASSANDRA-4694:
-----------------------------------------

>From description of populate_io_cache_on_flush option:
{code}
# The following setting populates the page cache on memtable flush and compaction
# WARNING: Enable this setting only when the whole node's data fits in memory.
# Defaults to: false
# populate_io_cache_on_flush: false
{code}

I'll try to describe my thoughts. Lets imagine that you have a few column families: cf1 and cf2. 
cf1 has a huge amount of data that doesn't fit in memory. Most of queries to cf1 use only small part of data (so-called hot data). You can use row cache for processing all these queries. 
cf2 has a acceptable size of data for in-memory storing. You can use populate_io_cache_on_flush option for fast reading of sstables from IO cache (from memory in fact). 

You are right about fix versions. I can migrate it to 1.2 version if it's needed. Should I do that?
                
> populate_io_cache_on_flush option should be configurable for each column family independently
> ---------------------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-4694
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-4694
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Alexey Zotov
>            Assignee: Alexey Zotov
>            Priority: Minor
>              Labels: cli, core, documentation
>             Fix For: 1.1.6
>
>         Attachments: cassandra-1.1-4694-populate_io_cache.txt
>
>
> I suggest to configure populate_io_cache_on_flush option for each column family. It should be configurable from cassandra-cli and should be stored in System keyspace. 
> That could be useful if you have a few column families inside single keyspace and you need to fit in memory only one of them.
> Patch has been attached. I've been testing it on pseudo-cluster using ccm. So I don't have fully confidence about lack of bugs. Please carefully review that code.

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