[jira] [Commented] (OAK-10494) Cache backend.getRecord() calls to minimise CloudBlob.downloadAttributes() over the network

["Axel Hanikel (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/OAK-10494?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17775712#comment-17775712 ] 

Axel Hanikel commented on OAK-10494:
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[~amitjain] Do you see any potential issues with this?

> Cache backend.getRecord() calls to minimise CloudBlob.downloadAttributes() over the network
> -------------------------------------------------------------------------------------------
>
>                 Key: OAK-10494
>                 URL: https://issues.apache.org/jira/browse/OAK-10494
>             Project: Jackrabbit Oak
>          Issue Type: Improvement
>          Components: blob-plugins
>            Reporter: Axel Hanikel
>            Priority: Major
>         Attachments: Measurements.md
>
>
> h1. Problem: Metadata are requested more than once for each blob
> Setting a breakpoint in {{AbstractSharedCachingDataStore.getRecordIfStored()}} and logging the dataIdentifiers, we see that it calls {{backend.getRecord()}} 3 times for the same {{dataIdentifier}} when a replication package is installed by vault. The reason seems to be that during commits, every {{CommitHook}} runs its own {{compareAgainstBaseState}} and, because the implementation avoids fetching the blob if it only needs the metadata, the request to the existing blob cache is always a miss.
> h1. Proposed solution: Cache {{backend.getRecord()}} calls
> Manual testing has shown that caching {{backend.getRecord()}} calls reduces the time spent in {{.getRecordIfStored()}} by between 12 and 35% when installing replication packages containing 500 paths.
> The PR is at https://github.com/apache/jackrabbit-oak/pull/1155



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