Force Merge

Official ElasticSearch documentation can be found here

Additional Notes

We use the force merge API in the past, when we've had a very large account purged and needed to free up disk space more quickly than letting the cluster clean it up on its own in the background and have seen disk space free up by 10% or more.

We have only done this on one index at a time in the past.

There is an optional parameter called only_expunge_deletes that basically, when set to true, indicates that you only want to free up disk space of deleted documents. If this is set to true, it seems that you don't need to worry about turning off writes to the index while it is running.

If you do not set only_expunge_deletes to true, it is recommended that you turn off writes to the index well the force merge task runs.

This could change over time, but at the time of writing, you can do this by turning off / disabling the following function apps / specific functions

• Turn off AtlantisSearch-Indexing function app

• Disable TikaExtractComplete function in revver-textExtractionProcessing function app

• Disable OCRExtractComplete function in revver-ocrProcessing function app
• Disable queue triggered functions in the AtlantisFileProcessing-ExtractedTextManagment function app (this is probably overkill, but I have not researched exactly with functions write to the index)