CachePrepared avoid compilation of the same sql statement several times.

CloseCashePrepared closes all prepared sql statements cache for cleaning memory at the server it is called upong program terminating as well as once in a 5 minute.

utilites to implement caching of prepared statements.

IsDuplicateError determines if an error is pq: duplicate key value violates unique constraint error.

IsNotFoundError determines if an error is sql.ErrNoRows.

Transaction is a wrapper function which helps to avoid the use of sql.DB instance directly.

GetDBLock obtains lock for lockInterval period and returns two functions: holdLock() continues to hold lock and refreshes it ech refreshInterval.