Re: ideas to use ora hash

  • From: David Aldridge <david@xxxxxxxxxxxxxxxxxx>
  • To: juancarlosreyesp@xxxxxxxxx, oracle-l@xxxxxxxxxxxxx
  • Date: Tue, 21 Mar 2006 06:06:17 -0800 (PST)

If you have to (anti) join to a table on a great many columns, as might be the 
case in a data warehouse fact table or a dimension table, then using a hash 
value computed across the set of columns can be a handy performance tweak. In 
particular it can save you from the need to create a monstrous composite index.

The tricky part is that the hash formula is not guaranteed to remain unchanged 
across versions, so storing hash values across upgrades can take some 
validation and possible recal.
----- Original Message ----
From: Juan Carlos Reyes Pacheco <juancarlosreyesp@xxxxxxxxx>
To: oracle-l@xxxxxxxxxxxxx
Sent: Tuesday, March 21, 2006 6:37:29 AM
Subject: ideas to use ora hash

Hi list
Does anyone has an interesting idea about how to use, specially for tuning,
ora_hash or DBMS_UTILITY.GET_HASH_VALUE, to get hash values.

One is to encrypt, but I was asking about the possibility to use to
reduce storage space or to tune, does anyone can share some idea
and/or experience.

Thank you :)
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