Lucene query filter for elasticsearch data source field and set up alert on grafana

Any Help will be appreciated.

Looking for some help in writing some advance lucene query or script to set up alerting.

I have a elasticsearch data source and having message field with following out put.

Message: [Eden: 3624.0M(3624.0M)->0.0B(3608.0M) Survivors: 63488.0K->69632.0K Heap: 5279.9M(6144.0)M->1633.4M->1633.0M(6144.0M) ]

Looking for set up alert when Heap value crosses 5000M will trigger an alert.

I am trying to write a lucene query in grafana dashboard to subtract the field Heap>5000M.

Thank you,