Semi-durable Tables

The idea is to be able to create tables that need not be fully durable. The durability of these tables will be equivalent to innodb_flush_log_at_trx_commit=0, where the log file is flushed every second.

This means that, at most, 1 second of committed data in the table can be lost. PBXT will determine if a transaction only involves this type of table. If so it will delay the log flush. If a transaction modifies at least one fully durable table, then the transaction log is flushed as usual.