Re: Measuring Rollback Usage

First, queries don't generate rollback. Only DML does that.

Second, v$rollstat joined with v$transaction will give you what you are after -in cunningly named fields like UBABLK and UBAREC. At least, you can use that to work out how much rollback a given transaction is generating. Whether that stuff is then being read by anyone else is much more difficult to work out (ie, I don't know a way of doing it... and I suspect there isn't a way, because if there were, we'd never have Snapshot Too Old errors).

Regards
HJR

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"Greg Stark" <greg-spare-1_at_mit.edu> wrote in message
news:877l6czn50.fsf_at_HSE-MTL-ppp62193.qc.sympatico.ca...


>

> Is there any way to measure how much rollback is being generated by each

> query, and for each how much of that rollback is actually being read?

>

> The goal here is to maximize the time that useful rollback is kept

 available


> by finding queries generating lots of rollback that isn't actually being

 read,


> and isolate that rollback in a separate rollback segment.

>

> --

> greg