[sitharus]

That doesn't sit well with Postgres' MVCC system, since between updates and VACUUMs you'd either need a secondary heap or the heap would need row-adjacent space reserved for the updates.

FWIW MS SQL Server has this problem with snapshot isolation. An inserted or updated row lives in TempDB until the DB finds time to push the rows back to the cluster (I can't recall exactly when), so the more insert/update heavy your workload is the more tempdb space you'll need. This also makes selects slower since it has to check the row map for ones that are current in tempdb.

Could work well for infrequently changing tables though.

[doug1001]

but if the snapshot is read-only? can the master rely on this config to avoid having to check the row map?