Tips and wisdom from 15 years of DBA experience

Monday, November 10, 2008

"Snapshot too old" is getting old.

ORA-01555: snapshot too old. We have all been there, we have all wrestled with it. We have all tried to solve the problem the wrong way at some point in our careers...admit it. It does not speak well for my constituency of Oracle DBAs that one of the most common Oracle errors is also one of the least well-understood. My theory is that the error is just rare enough that many DBAs do not feel it is necessary to dig into how Oracle's read consistency mechanism works in order to solve a problem that will probably go away the next time the batch job runs anyway. I could go into an explanation, but that would be re-inventing the wheel. Folks, if you manage an Oracle database, take 30 minutes to read about Ora-01555 on - it will save you a lot of time and improve your credibility because you will fully understand why it happens.

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