To improve performance of conventional export (exp) and import (imp) , is it better to use BUFFER parameter always ?
If yes , then the from which area the BUFFER is accessing memory in original exp/imp .
it is better to use expdp & impdp to replace obsoleted exp & imp utilities.
With exp and imp utilities the buffer= parameter allocates buffer space from the OS. These are command line utilities and the buffer is used to hold export file (dump file) blocks. With conventional export and import I have found this to be a very beneficial parameter.
HTH -- Mark D Powell --
Thanks For reply ..
But I just want to know , BUFEER memory allocation to exp operation is done where ?
BUFFER allocation comes from RAM
I've found DIRECT=Y compress=N recordlength=65535 faster for my situation. See also Screaming Imports keeping in mind there may be some outdated information on the intertubes.
Thanks for the reply ...
Further to your reply , I have noted down what i have understood on Export using (BUFFER,RECORDLENGTH )
Please help me if i am wrong anywhere .
BUFFER size is allocated in the RAM (client side ) of client side (from where the utility is running ) .
In conventional export if you have a tuned BUFFER size , then it improves the performance as because it will reduce the sqlnet round trip to the Database Server .
As RECORDLENGTH specifies i/o for export operation , so we should use this parameter to improve the writing of data from the buffer to the export file .
But If we put DIRECT=Y then BUFFER parameter won't be respected .Because " The
BUFFER parameter applies only to conventional path Export. It has no effect on a direct path Export. For direct path Exports, use the
RECORDLENGTH parameter to specify the size of the buffer that Export uses for writing to the export file.
In DIRECT=Y , the export will be faster , is it only because of that it bypass the db_buffer and the requested data will directly come to the export session's program global area (PGA).
What i am trying to ask is .....
In DIRECT=Y .... there is no BUFFER memory associated with it , does it not increase the round trip of sqlnet .