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From "Jim Kellerman (JIRA)" <j...@apache.org>
Subject [jira] Resolved: (HBASE-632) HTable.getMetadata is very inefficient
Date Wed, 04 Jun 2008 04:56:45 GMT

     [ https://issues.apache.org/jira/browse/HBASE-632?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Jim Kellerman resolved HBASE-632.
---------------------------------

    Resolution: Fixed

Committed.

> HTable.getMetadata is very inefficient
> --------------------------------------
>
>                 Key: HBASE-632
>                 URL: https://issues.apache.org/jira/browse/HBASE-632
>             Project: Hadoop HBase
>          Issue Type: Improvement
>          Components: client
>            Reporter: Bryan Duxbury
>            Assignee: Jim Kellerman
>            Priority: Minor
>             Fix For: 0.2.0
>
>
> The current implementation of HTable.getMetadata is very inefficient. In order to find
the HTableDescriptor, it does a full meta scan for all table names. Then, it selects the one
that matches the table we're looking for. That's a huge number of operations to satisfy a
very simple question. To make matters worse, it doesn't even cache the result it gets - subsequent
calls will go right back out to a meta scan.
> At the very least, we should only look up the first meta row for a given take and do
it as a random read. We should consider caching the result, or even just grabbing it during
table creation (as we will check meta to make sure the table you're opening exists). Of course,
if we move table descriptors out of META altogether (maybe into Zookeeper?) then this will
have to be revisited no matter what.

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