[
https://issues.apache.org/jira/browse/DERBY-2878?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Knut Anders Hatlen updated DERBY-2878:
--------------------------------------
Attachment: derby-2878-1.stat
derby-2878-1.diff
Attached is the first step towards eliminating the allocation of protection
handles. It adds a method to Page/BasePage called getProtectionRecordHandle().
This method creates a new record handle if it hasn't been called before and
returns a cached value otherwise. B2IRowLocking3.lockScan() and
lockScanForReclaimSpace() have been modified to use the new method.
unlockScan() still allocates a protection handle since it cannot access the
page object, but it should be fairly easy to make it reuse the handle too.
suites.All and derbyall passed.
> 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: Performance, Store
> Affects Versions: 10.4.0.0
> Reporter: Knut Anders Hatlen
> Assignee: Knut Anders Hatlen
> Priority: Minor
> Attachments: derby-2878-1.diff, derby-2878-1.stat
>
>
> 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.
