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https://issues.apache.org/jira/browse/DERBY-2878?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Knut Anders Hatlen updated DERBY-2878:
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Attachment: derby-2878-2.diff
Attaching new patch (derby-2878-2.diff) which is a pure refactoring of
BTreeScan. It adds a private method called unlockCurrentScan() to the class,
and replaces all occurrences of
- if (pos.current_scan_pageno != 0)
- {
- this.getLockingPolicy().unlockScan(pos.current_scan_pageno);
- pos.current_scan_pageno = 0;
- }
with a call to that method. This makes it simpler to reuse the protection
handle for unlockScan() since there are fewer places that need modification.
Derbyall and suites.All 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,
> derby-2878-1b.diff, derby-2878-2.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.
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