recently, i have been facing snapshot too old error. So, i tried to understand the why this is happening. Link to the snapshot too old article Still, i have some doubts regarding the error.
- If i run a select query on a table with millions of data and new data are being inserted into the table, does it cause the above error? Doesn't it change the image captured b4 running the query?
10AM query starts, never ends
11AM query starts, never ends
Noon query starts, never ends
1PM query starts
Meanwhile, the undo needed from the 10AM query for the 1PM query gets overwritten, 1PM query dies with ORA-01555, since it needs to know what the table looked like before the 10AM query started mucking with it.
Also if the query is a loop with a commit in it, it can do the same thing without other queries, as eventually the next iteration requires looking back at it's own previous first generation, can't do it, and barfs."
Above statements are taken from the link given above. I don't understand the highlighted part. Does it says that if i add a commit after delete statement with in a loop, then next iteration results in an error. But, i have been doing such things for sometime and i haven't got any error.
Please help me clear these doubts.