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Vikas Saurabh commented on OAK-2808: ------------------------------------ Discussed this a bit with [~chetanm] offline. I was of the idea that maybe we can commit a delete list. But, in current scenario, the delete list is pretty unbound and itself might cause issues down the line. So, we might be better off with the best-effort-basis approach. Also, for bq. We go over all lucene index definition and mark the blobids we can add a buffer around the min_time_at_which_blobs_are_safe_to_delete of say 1/2 or 1 hour (the only case I know is when segstore can rollback a bit during ungraceful shutdowns) - so, basically, we should delete blobs deleted before min(oldest_checkpoint_timestamp, curTime-1Hour) > Active deletion of 'deleted' Lucene index files from DataStore without > relying on full scale Blob GC > ---------------------------------------------------------------------------------------------------- > > Key: OAK-2808 > URL: https://issues.apache.org/jira/browse/OAK-2808 > Project: Jackrabbit Oak > Issue Type: Improvement > Components: lucene > Reporter: Chetan Mehrotra > Assignee: Thomas Mueller > Labels: datastore, performance > Fix For: 1.8 > > Attachments: copyonread-stats.png, OAK-2808-1.patch > > > With storing of Lucene index files within DataStore our usage pattern > of DataStore has changed between JR2 and Oak. > With JR2 the writes were mostly application based i.e. if application > stores a pdf/image file then that would be stored in DataStore. JR2 by > default would not write stuff to DataStore. Further in deployment > where large number of binary content is present then systems tend to > share the DataStore to avoid duplication of storage. In such cases > running Blob GC is a non trivial task as it involves a manual step and > coordination across multiple deployments. Due to this systems tend to > delay frequency of GC > Now with Oak apart from application the Oak system itself *actively* > uses the DataStore to store the index files for Lucene and there the > churn might be much higher i.e. frequency of creation and deletion of > index file is lot higher. This would accelerate the rate of garbage > generation and thus put lot more pressure on the DataStore storage > requirements. > Discussion thread http://markmail.org/thread/iybd3eq2bh372zrl -- This message was sent by Atlassian JIRA (v6.3.15#6346)