runs one SQL statement
dialect-correct identifier quoting (PG folds unquoted case)
true for a failure of the connection rather than of the query
Builds the combined statement. Exposed for tests.
Called by view index in place of executing its count SQL. Resolves with
that view's count rows once the batch flushes.
Called when view index has finished (success or failure). A view that
never registered a count (failed before the count step, external entity)
must still be counted as arrived, or the batch would wait forever.
number of views in the batch