How snapshot works and its impact

Hi all,

I have multiple question

  1. How the snapshot module works ?
  2. How it knows where exactly to snapshot when using incremental snapshot ?
  3. Is it a simple search query ?
  4. The impact in term of cpu ?

Thank you all.


A bit old but this should explain :

Thanks David,

The link answers to the first two questions. For the third and the fourth ? Do you have an idea ?


Lucene is the underlying search engine and it only creates new files - it never updates them.
The activity of indexing flushes new mini-indexes out to disk as "segment files". Lucene background tasks merge small segments into larger ones as a form of compaction and then delete the newly redundant segments. You can see this process here [1].
Snapshot is only concerned with copying over the segment files that are created since the last time you ran a snapshot. No queries required - it's just syncing sets of files.


Thanks Mark,

Last question, does the snapshot could impact the search thread pool ?
All this questions, because I have created a cron that call the snapshot api each hour. And each hour I see the thread pool of the search requests reaching its limit to 1000...

For information I'm on 1.7 version !


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