SQL Server Performance Tuning
Why is it better to use RAID 1 for the operating system, SQL Server binaries, and the swap file? What advantages does RAID 1 have over RAID 5?
Both hardware RAID 1 (mirroring or duplexing) or RAID 5 (striping with parity) offer good data redundancy should a single hard disk in a RAID array fail. And as you might expect, there is some differences in performance between the two. The major difference in performance between RAID 1 and RAID 5 is that RAID […]
Question I’m facing a concurrency problem with SQL Server. If one user is in a transaction and is updating a particular table, then other user’s aren’t able to read any data from that table at all. The other user application’s hang and wait until the first user either commits or rollbacks the transaction. This is […]
My question is how do I move already existing log files in a different drive, or how can I separate data files and log files into different drives?
Question I am just starting as a DBA in a new company. We are running a single SQL server. We have about 15 databases, the largest being 2 GBs. During peak hours and weekends, there are several hits on the server that affect performance. I found out that the data files and log files are […]
In the past couple of weeks, my SQL Server seems to be running slower. Queries just don’t seem to run as fast. What should I do?
While this is a simple question, it is not an easy one to answer. If fact, one of the reasons I developed this website was to help answer this question. It would take a very long article to address all the potential causes of a SQL Server getting slower over time (which won’t be done […]
Should I schedule the indexes in my SQL Server databases to be rebuilt before or after the statistics on my tables are updated (or does it matter)?
If you are using SQL Server and if you have the database options “Auto Create Statistics” and “Auto Update Statistics” turned on (which they should be for best overall performance), then you normally don’t need to manually update statistics. In addition, if you rebuild a table’s indexes (which should be done often, such as once […]
We have a started experiencing a performance issue with a table that has now grown to over 600,000 rows.
Question We have a started experiencing a performance issue with a table that has now grown to over 600,000 rows. Performance has become unsatisfactory when accessing this table. I haven’t ever run DBCC INDEXDEFRAG on this table. I was wondering if after running it on this table, if performance will improve? Does the performance problem […]
Question Our SQL Server is dual processor server and I notice that overnight when we run certain jobs than one CPU is favored over the other. The favored CPU varies from day to day, but if I look at the difference between the CPU’s utilization, there is a definite trend to favor one CPU at […]
Question When I monitor my SQL Server, I can see that the buffer cache size (number of pages) grows through out the day as the number of user connections increase. This cache size varies between 2-3MB to 30-35MB. The server has 256MB and is dedicated to running SQL Server. The buffer cache hit ratio is […]
Do you have a recommendation for the maximum number of databases you can place on a single SQL Server?
Question Do you have a recommendation for the maximum number of databases you can place on a single SQL Server? I understand the memory and drive size requirements are big factors, but is there a maximum recommended number of actual databases you should place on a single SQL Server instance on a single server? AnswerThe total […]
When I run a stored procedure in Query Analyzer, it runs in about two minutes. But if I execute the same stored procedure as a job, it runs several hours.
Question When I run a particular stored procedure in Query Analyzer, it runs in about two minutes. But if I execute the same stored procedure as a scheduled job, it runs several hours before it completes. What could be the obvious reasons for this? AnswerWhen I first got this question, I didn’t have an answer. […]