Forcing garbage collection with in memory oltp

To force manual garbage collection:

1. First we check the status of the checkpoint files:

select container_id,state_desc,lower_bound_tsn,upper_bound_tsn from sys.dm_db_xtp_checkpoint_files

Anything that is MERGE TARGET is pending a merge.

In SQL Server 2014 we can run:

sys.sp_xtp_merge_checkpoint_files database_name, @transaction_lower_bound, @transaction_upper_bound

to force a merge, manual merges are not possible in SQL Server 2016!

2. Once the merge is complete we have to run a checkpoint to ensure everything is persisted on disk.

3. Next we need to run a log backup otherwise dm_db_xtp_checkpoint_files.state_desc would be ‘WAITING FOR LOG TRUNCATION’

4. Finally we can force garbage collection using

sys.sp_xtp_checkpoint_force_garbage_collection [[ @dbname=database_name]

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