On 11/18/2010 4:56 PM, Fredric Fredricson wrote:
Hi, I have designed a handful databases but is absolutely no SQL-expert. Nor have I had any formal database training and have never worked with someone who had. What I know about SQL I have read in the documentation, found with google, and learned from my numerous mistakes. This question I have is somewhat related to the "unlogged tables" proposal that is discussed in another thread. The background is that I am designing a data storage that, unlike all other data storage, have some performance requirements (yes, that was a joke ;-). What I have done to handle this is to create "lookup" tables that cache preprocessed information. The simplest is row count but also results from selects with joins and group clauses. These tables are updated either on demand (first call), by triggers, or periodically. I assumed this was fairly standard practice and when I read about unlogged tables these tables was the first use that came to my mind. Since the lookup tables are used for performance and contain redundant data loosing the data at a restart is no real problem. What puzzle me though is that this use is never mentioned in the discussions, at least as far as I can see. Am I doing something "strange"? Is this something you should not have to do if you have "proper" database design? Regards /Fredric
unlogged will only help insert/update performance. Lookup tables sound readonly for a majority of time. (I'm assuming lots of reads and every once and a while updates). I doubt that unlogged tables would speed up lookup tables.
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