Re: Order of fields in a table.

> If you use LONG datatypes, they should sensibly be the last columns in the
> table, because access to them is sequential and they are always stored
> in-line with your other data (meaning getting at that other data would
> require you to wade through the entire LONG if it was stored in a column
> positioned before it).

Actually LONGs are *always* stored as last columns in row, no matter what you specify in create table statement. This is an Oracle internal optimization.

SQL> create table l (a number, b long, c number);

Table created.

SQL> select obj# from obj$ where name = 'L';

      OBJ#

     30120

SQL> select name, col#, segcol# from col$ where obj# = 30120;

NAME                                 COL#    SEGCOL#
------------------------------ ---------- ----------
A                                       1          1
B                                       2          3
C                                       3          2

SEGCOL# shows the physical column ordering, COL# shows ordering what we see using describe command.

Tanel. Received on Sat Jul 05 2003 - 10:15:26 CDT