An example on my understanding of Reverse Key Indices:
Say you have a table EMP with a column EMPNO, and an index on this
field.This number is incremented sequentially for every new employee that
joins in. And as employees retire, say, the records are deleted. This
would generally mean deletion of records, with lower employee numbers. And
subsequent deletion of indices. As such, deletions from the index are
likely to be concentrated on a small set of leaf blocks towards the
beginning of the index. A reverse key index, which reverses the bytes for
the column value, could help in uniformly dividing the deletions across
various branches of the index, and avoid a skewed index.
Raj
One attachment (0k)
"Jamadagni,
Rajendra" To: Multiple recipients of list
ORACLE-L <[EMAIL PROTECTED]>
<Rajendra.Jamadagni cc:
@espn.com> Subject: RE: Index & Constraint
Sent by:
[EMAIL PROTECTED]
June 07, 2002 04:33
PM
Please respond to
ORACLE-L
No, don't use reverse index for FKs, on certain versions they caused havoc
by allowing parent key to be deleted (Metastink has an alert on this one).
Reverse indexes are preferred in OPS environment AFAIK.
Raj
______________________________________________________
Rajendra Jamadagni MIS, ESPN Inc.
Rajendra dot Jamadagni at ESPN dot com
Any opinion expressed here is personal and doesn't reflect that of ESPN
Inc.
QOTD: Any clod can have facts, but having an opinion is an art!
(See attached file: InterScan_Disclaimer.txt)
InterScan_Disclaimer.txt
Description: Binary data
