Re: Please define ROW CHAINING!!!
From: Randy Fought <FOUGHTRL_at_CTRVAX.VANDERBILT.EDU>
Date: 1995/09/27
Message-ID: <44bqvi$1ih_at_news.vanderbilt.edu>#1/1
> I am teaching myself -trying to at least- Oraclle. I monitor this
> newsgroup as one of my resources. Could someone please tell me
> what Row Chaining is?
>
> Thank you.
>
> Nabil - ncourdy_at_winternet.com
Row chaining occurs when a record cannot be stored in the same Oracle data block. This usually occurs when a record is updated and becomes 'wider'. Adding a column, increasing the width of a column or simply changing a columns value can cause a record to need more space.
Date: 1995/09/27
Message-ID: <44bqvi$1ih_at_news.vanderbilt.edu>#1/1
ncourdy_at_parka.winternet.com (Nabil Courdy) wrote:
>
> I am teaching myself -trying to at least- Oraclle. I monitor this
> newsgroup as one of my resources. Could someone please tell me
> what Row Chaining is?
>
> Thank you.
>
> Nabil - ncourdy_at_winternet.com
Row chaining occurs when a record cannot be stored in the same Oracle data block. This usually occurs when a record is updated and becomes 'wider'. Adding a column, increasing the width of a column or simply changing a columns value can cause a record to need more space.
Usually, the datablock that stores the record has enough
free space to insert this new data for the record into the same
datablock. However, if there is not enough free space then the
row (record) is chained. Part of the record is in the original
datablock and part of the record is placed in another datablock.
Obviously this degrades performance. If you will be increasing
the width of records after the table is first populated then
you should set the pctfree parameter high enough to accommodate
future expansion.
Hope this helps, Randy
Received on Wed Sep 27 1995 - 00:00:00 CET