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Posted to commits@cassandra.apache.org by "Wei Deng (JIRA)" <ji...@apache.org> on 2016/07/21 07:18:20 UTC
[jira] [Updated] (CASSANDRA-3952) avoid quadratic startup time in
LeveledManifest
[ https://issues.apache.org/jira/browse/CASSANDRA-3952?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Wei Deng updated CASSANDRA-3952:
--------------------------------
Labels: lcs lhf (was: lhf)
> avoid quadratic startup time in LeveledManifest
> -----------------------------------------------
>
> Key: CASSANDRA-3952
> URL: https://issues.apache.org/jira/browse/CASSANDRA-3952
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Jonathan Ellis
> Assignee: Dave Brosius
> Priority: Minor
> Labels: lcs, lhf
> Fix For: 1.1.0
>
> Attachments: speed_up_level_of.diff
>
>
> Checking that each sstable is in the manifest on startup is O(N**2) in the number of sstables:
> {code}
> . // ensure all SSTables are in the manifest
> for (SSTableReader ssTableReader : cfs.getSSTables())
> {
> if (manifest.levelOf(ssTableReader) < 0)
> manifest.add(ssTableReader);
> }
> {code}
> {code}
> private int levelOf(SSTableReader sstable)
> {
> for (int level = 0; level < generations.length; level++)
> {
> if (generations[level].contains(sstable))
> return level;
> }
> return -1;
> }
> {code}
> Note that the contains call is a linear List.contains.
> We need to switch to a sorted list and bsearch, or a tree, to support TB-levels of data in LeveledCompactionStrategy.
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