db-derby-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Dag H. Wanvik (JIRA)" <j...@apache.org>
Subject [jira] Updated: (DERBY-2878) Scan protection handle could be cached in BasePage
Date Mon, 29 Jun 2009 14:09:47 GMT

     [ https://issues.apache.org/jira/browse/DERBY-2878?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Dag H. Wanvik updated DERBY-2878:

    Derby Categories: [Performance]

> Scan protection handle could be cached in BasePage
> --------------------------------------------------
>                 Key: DERBY-2878
>                 URL: https://issues.apache.org/jira/browse/DERBY-2878
>             Project: Derby
>          Issue Type: Improvement
>          Components: Store
>    Affects Versions:
>            Reporter: Knut Anders Hatlen
>            Assignee: Knut Anders Hatlen
>            Priority: Minor
>             Fix For:
>         Attachments: derby-2878-1.diff, derby-2878-1.stat, derby-2878-1b.diff, derby-2878-2.diff,
derby-2878-3.diff, derby-2878-3.stat, derby-2878-3a.diff
> Each time a leaf node in a B-tree is visited in an index scan, a scan protection row
is locked and unlocked. Both the lock operation and the unlock operation will allocate a new
RecordId object representing the scan protection row (the unlock operation additionally allocates
a PageKey object for the RecordId). Since the scan protection handle created will be identical
(seen from equals()) each time it is created for a page, it would make sense to cache it in
BasePage. Then we only need to allocate the protection handle for a page once for as long
as it stays in the page cache. This would save three object allocations per single-record
lookup via index.

This message is automatically generated by JIRA.
You can reply to this email to add a comment to the issue online.

View raw message