Thursday, January 26, 2006

related conferences:
sigmod, icde, vldb, sigcomm, hotnets, iptps, dbisp2p, webdb

Monday, January 16, 2006

reader/writer

from http://cne.gmu.edu/modules/ipc/orange/readmon.html

  monitor ReadersWriters
condition OKtoWrite, OKtoRead;
int ReaderCount = 0;
Boolean busy = false;


procedure StartRead()
{
if (busy) // if database is not free, block
OKtoRead.wait;
ReaderCount++; // increment reader ReaderCount
OKtoRead.signal();

}

procedure EndRead()
{
ReaderCount-- ; // decrement reader ReaderCount
if ( ReaderCount == 0 )
OKtoWrite.signal();
}


procedure StartWrite()
{
if ( busy || ReaderCount != 0 )
OKtoWrite.wait();
busy = true;
}

procedure EndWrite()
{
busy = false;
If (OKtoRead.Queue)
OKtoRead.signal();
else
OKtoWrite.signal();
}

Reader()
{
while (TRUE) // loop forever
{
ReadersWriters.StartRead();
readDatabase(); // call readDatabase function in monitor
ReadersWriters.EndRead();
}
}

Writer()
{
while (TRUE) // loop forever
{
make_data(&info); // create data to write
ReaderWriters.StartWrite();
writeDatabase(); // call writeDatabase function in monitor
ReadersWriters.EndWrite();
}
}

Wednesday, January 04, 2006

view over distributed database

early days, there are works on this topic: view management in distributed data base systems (E. Bertino et al.)...

Tuesday, January 03, 2006

queuing

A queue is only useful if the production rate is greater than consumption rate for a limited burst time only. These bursts should be spread out in time.

Monday, January 02, 2006

when network latency below disk access time

As network latency drops below disk latency, access time to a remote disk will
begin to approach local disk access time. ..

http://www.cs.umd.edu/Library/TRs/CS-TR-3082/CS-TR-3082.abs

testing should fix one variable

instead of making each run by using different seeds, I should use the same seed for different runs, since the data and block size keep changing, which are the parameters I care about, so the lesson is: fix those uninterested things.