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CanadaDBA
583 Posts |
 Posted - 2005-02-24 : 15:15:09
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| I ran the PERFMON and noticed that our buffer cache hit ration is running at nearly 100% meaning that all queries are being serviced out of cache rather than from disk. This tells me the SQL Server is loading both our DBs into cache. As we add more databases, the ability for SQL Server to do this will be diminished meaning that both current DBs performance will suffer?Canada DBA |
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Bustaz Kool
Master Smack Fu Yak Hacker
1834 Posts |
Posted - 2005-02-24 : 16:07:22
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| The cache doesn't hold the database, per se, just the data to be read and written. The 100% Cache Hit Rate does indicate that you're doing great...so far. As more databases, or data for that matter, are added the ability of the SQL Server to continue to pull data from cache will be taxed. At what point does this have an impact on your performance? The answer is, as always, "that depends". The cache exists as a resource of the SQL Server; not the Database. There is one cache (per SQL Server Instance). If it gets overburdened, it will impact all of the databases that make use of it. How much this will impact each database is a function of how each data element is used. A table that rarely gets read or written will not likely be in cache when asked to process data. Another table which gets read frequently will still have a high cache hit rate. Why? Because as soon as it gets flushed (if ever), the next request causes it to get reloaded.HTH=================================================================Don't say you don't have enough time. You have exactly the same number of hours per day that were given to Helen Keller, Pasteur, Michaelangelo, Mother Teresa, Leonardo da Vinci, Thomas Jefferson, and Albert Einstein.-H. Jackson Brown, Jr., writer |
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Using buffer cache