Re: Buffer Waits

> hmm, could you go into a bit detail on the light-scan? I have a DSS system > but I am not sure how to make it use light scan. I read something on the > book about it, but it wasn't very clear on exactly how to utilize it or > how to check it. thanks yan There's a blurb about it in the Performance manual: "Under the appropriate circumstances, Dynamic Server can bypass the LRU queues when it performs a sequential scan. A sequential scan that avoids the LRU queues is termed a light scan. Light scans can be used only for sequential scans of large data tables and are the fastest means for performing these scans. System catalog tables and tables smaller than the size of the buffer pool do not use light scans. Light scans are allowed under Dirty Read (including nonlogging databases) and Repeatable Read isolation levels." In order to get light scans, you have to meet two conditions: * Tables have to be larger than the buffer pool * Locks don't matter Depending on the version, you can do "onstat -g lsc" for light scan info.