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https://issues.apache.org/jira/browse/OAK-6165?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15996363#comment-15996363
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Marcel Reutegger commented on OAK-6165:
---------------------------------------
Queries on _sdType are not yet frequent, but will be when continuous revision
GC is employed (OAK-3710). I have a test system running where I simulate this
with the oak-run "revisions collect" command using the {{--continuous}}
options. This command calls the revision GC every five seconds. On MongoDB it
issues a query like this (among others) when the system is a two node cluster:
{noformat}
{
$and: [
{ _sdType: { $exists: true } },
{ $or: [
{ _sdType: 50 },
{ _sdType: 60 },
{ _sdType: 70,
$and: [ { $or: [ { _id: /.*-1\/0/ }, { _id: /[^-]*/, _path: /.*-1\/0/ }
] } ],
_sdMaxRevTime: { $lt: 1489069960 } },
{ _sdType: 70,
$and: [ { $or: [ { _id: /.*-2\/0/ }, { _id: /[^-]*/, _path: /.*-2\/0/ }
] } ],
_sdMaxRevTime: { $lt: 1489069960 } }
] },
{ _sdMaxRevTime: { $lt: 1489069960 } }
]
}
{noformat}
Without a compound index, the store is forced to scan all documents with an
{{_sdType}} field. Running such a query on a moderately sized 1.6 repository
(~60GB), leads to response times ranging from seconds to minutes, depending on
how much page faulting is necessary. With a compound index in place, I get an
instantaneous result.
> Create compound index on _sdType and _sdMaxRevTime (RDB)
> --------------------------------------------------------
>
> Key: OAK-6165
> URL: https://issues.apache.org/jira/browse/OAK-6165
> Project: Jackrabbit Oak
> Issue Type: Improvement
> Components: rdbmk
> Reporter: Chetan Mehrotra
> Assignee: Julian Reschke
> Fix For: 1.8
>
>
> Clone for OAK-6129 for RDB i.e. create index on OAK-6129on _sdType and
> _sdMaxRevTime. This is required to run queries issued by the Revision GC
> efficiently.
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