Re: What is table fetch continued row

Anurag

Boy, you're having a busy time asking questions! It's a good way to learn, though.

Table fetch continued row indicates the sum of both chained and migrated rows. Chained rows are ones that are larger than the block size, so multiple blocks are required to store the row. The only thing you can do to minimize this is increase the database block size. Given the trend to storing BLOB's etc., chained rows are probably inevitable and you don't need to do anything with them.

Migrated rows is a different issue. These are rows that have been updated, where the update has increased the row size and the row needs more space than is available in its current block. The result is that the row is migrated to another block, and a pointer left behind in its original location to say its new address is in the other block. I/O to get the row has just been doubled. Export / import will remove the need for the pointer.

The only problem is there is no statistic that shows you how many rows are migrated versus how many are chained. The only way to identify this is to know your data.

HTH. Pete

Anurag Minocha wrote:

> Hi,
>
> I have seen people using the query:--
>
> select name,value from v$sysstat where name
> 2 like 'table fetch continued row';
>
> What does table fetch continued row mean.
>
> any help will be appreciated.
>
> Thanks
> anurag
>
> reply at
> anurag_at_synergy-infotech.com

--
Regards

Pete

Received on Fri Jul 23 1999 - 11:28:52 CDT