Execute an insert to an append-only store. If less than expectedRowsInserted are found inserted perform a select and verify that the existing data is what we expect to existing in our store. If the existing data fails the provided check predicate a java.lang.IllegalStateException will be thrown as this indicates either a bug or a configuration error (such as a new node running with a database initialized by another node). If more rows are returned than expectedRowsInserted a java.lang.IllegalStateException is also thrown as this indicates the insert query is doing something contrary to the developers expectations and is likely a bug.

Typical usage will look like:

insertVerifyingConflicts(
  sql"insert into my_table (pk_col, name) values ($$id, $$name) on conflict do nothing".asUpdate,
  sql"select name from my_table where pk_col = $$id".as[String].head // query values to check successfully exist in the target store.
)(
  _ == name,
  existingName => s"Expected row $$id to have name $$name but found existing name $$existingName"
)

Note that no transaction is started within this method and therefore changes could become visible between the insert and the select that we may then perform. However as the usage of this is intended for append-only stores separate modifications of this data is not expected.

Regarding performance the select statement will only be executed if the returned inserted row count is different from the expectedRowsInserted value. We anticipate this happening potentially due to crashes or retries due to connectivity issues, and should be rare during normal healthy operation. So typically only the insert should be run.