I believe the answer is c and e.
A will help snapshot too old problem.
If B was the problem then we would get an media error
C will help snapshot too old problem.
If D was the problem then we would get a out of space error
E could shrink rollback segs and thus make the problem worse.
A and C can not fix snapshot too old, but can hopefully delay it long enough
that the query can finish.
Snapshot too old happens during selects.
selects only read the rollback for read consistency.
lets say I do a long running select. As the select is running
someone updates the same rows that I am selecting. No problem.
but my query can not use the updated data.
So the update is done. and COMMITTED. my select still can not use
the new data. It has to use the old data. No problem. Data is still
in the rollback. But if the database has lots of transactions it is
only a matter of time b4 the rollback data gets over written. Because
the locks on the rollback data are gone because of the commit; Oracle
is free at any time to over write the rollback data. Once that happens,
snapshot too old.
now by increasing the number of rollbacks segs, it will take longer for the
rollback data to be over written. Same with larger extent size. Or
increasing
min extents will help.
The best solution is to get the queries to run faster.
I hope that I am not full of it. But it at least sounds right to me.
If I am wrong I hope someone will correct me!!!!
peace
-----Original Message-----
From: hrishy [mailto:[Email Address Removed] Friday, November 30, 2001 12:47 AM
To: LazyDBA.com Discussion
Subject: Question simple one
Hi All
An Oracle user receives the following error:
ORA-01555 SNAPSHOP TOO OLD
What are two possible solutions?
A. Increase the extent size of the rollback segments.
B. Perform media recovery.
C. Increase the number of rollback segments.
D. Increase the size of the rollback segment
tablespace.
E. Increase the value of the OPTIMAL storage parameter
whats the answer ?i have answered A&E but c also seems
to be right Na ?
regards
Hrishy
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