Re: Difference between ROWNUM & ROWID

From: Dan Clamage <clamage_at_mime.dw.lucent.com>
Date: 1997/09/17
Message-ID: <01bcc375$99dd7a30$54110b87@clamagent>#1/1

Every row in a table has a unique rowid which corresponds to the physical address of the row. The format is block.row.file as in 00000DD5.0000.0001 (this is straight out of Application Developer's Guide). When an index is built, the entries are a key and the rowid. Oracle can search on the key and then fetch the entire row using the rowid.

Rownum is a pseudocolumn (not an actual colum in the table, but something kept track of by the SQL engine) that depicts the ordinal value of rows as in:

rownum      name
------      ----------------
1		fred
2		dan
3		george
4		nancy

I've never heard of concatenating indexes... perhaps you mean composite indexes? which are indexes composed of more than 1 column from the table.

Dan Clamage

SKMGMT <skmgmt_at_aol.com> wrote in article <19970917020100.WAA25417_at_ladder02.news.aol.com>...
> CAN someone kindly tell me the difference between the two.
>
> Also what is Concatenating indexes.
>
Received on Wed Sep 17 1997 - 00:00:00 CDT