Support for database/user/client based aggregates added to access
these statistics with three new views added. Some new counters added
including min/max/mean's time histograms. We are saving the parameters
of the slow queries, which can be tested later. Did some refactoring
of the code, by renaming the whole extension from pg_stat_statement to
pg_stat_monitor.
The pg_stat_monitor is based on PostgreSQL-11's pg_stat_statement.
To keep track of the changes, this is the base code of
PostgreSQL's pg_stat_statement.
(commit = d898edf4f233a3ffe6a0da64179fc268a1d46200).
Ibrar Ahmed