I have a question about replication as it pertains to LOBs (BLOBs and CLOBs). According to the documentation...
If the master looses connection with the slave, "transactions are allowed to continue processing while the master tries to reconnect with the slave. Log records generated while the connection is down are buffered in main memory. If the log buffer reaches its size limit before the connection can be reestablished, the master replication functionality is stopped." And the documentation for derby.replication.logBufferSize says the maximum size of the buffer is 1048576 (1MB). This seems to imply that if I have a database in which I store LOBs which are, for example, 256K in size, and the connection between master and slave is severed, I can perform 4 inserts or less before the master gives up. Is this so? If this is in fact the case, I would like to file a request that this limit be raised considerably or eliminated altogether. I have two servers (master and slave) running 64-bit JVMs, 64GB of memory each, SSD drives, connected by 10GbE fiber. I would like to dedicate as much memory as I want to deal with a disconnect/resume scenario (to avoid the onerous failover). At an insertion rate of 16 rows per second (~4MB), currently the setup would tolerate a connection interruption of a fraction of a second. A 1GB buffer would afford a connection interruption of ~250 seconds (for example, rebooting the fiber switch). Last question, aimed at devs, why does Derby even bother to buffer logs in memory? Can't it just keep an offset/marker into the transaction log files, and replay transactions from there, rather than buffering them in memory? Regards, Brett