Hi Michel
Joins can be performed in one of three manners
nested loops (retrieve one row from a master table, subsequently retrieve
all rows from the corresponding detail table)
merge-join (join is performed by executing a sort, all applicable rows are
buffered in memory)
and hash-join (a hash key is being calculated and this key is used for
sorting purposes. In merge-join the complete select expression is sorted)
Turning the parameter off simply means you can't use it.
Now this hash-join mechanism might (?!) be supported by the cost based
optimizer only. I have a feeling if you are running rule based (this happens
with optimizer_mode = choose and if you don't have statistics in the
dictionary) it won't be used anyway.
Hth,
Sybrand Bakker, Oracle DBA
Michel Gauthier wrote in message ...
>Hi all,
>
>After having a few ORA-600 [15851] [6] [6] etc... I searched the Oracle Web
>support to find out that they sometimes suggest to turn off the
>HASH_JOIN_ENABLED parameter. This parameter seems to appear with 7.3 and
I'm
>not familiar with it. Anyway, I turned it off, and it seems to actually
>work. Fine.
>
>Unfortunately, that does not say what this parameter is useful to, neither
>which are the impacts to turn it off (except it workaround my problem!). I
>surfed the Oracle doc and DEJANEWS without success.
>
>Can anybody tell us about this parameter. That would be nice.
>
>TIA.
>
>Michel Gauthier
>
>
Received on Fri Apr 30 1999 - 16:02:47 CDT
