[Advanced-java] Memory consumption & performance

[Lothar Kimmeringer]

Marco Ferretti wrote:
> I am i the web scenario : there is a client that wants to upload one or more 
> files and I _have_ to record them in a database ( the real file, not the 
> position and write the file somewhere in the filesystem ) . I am using 
> Jakarta commons.fileupload libs to get the data from the client; a servlet , 
> then, creates an SQL string using a StringBuffer. Now, since the client can 
> upload more than one file at the time I was wondering, in a production state, 
> wether of  using StringBuffer.delete() or simply a new StringBuffer is the 
> best approach towards memory consumption & performance ... or if there's a 
> better way to do it .

If the statement itself is always the same, like

insert into mytable (col1, col2, col3, col4) values (...)

where only the values-part is changing, you should use
PreparedStatement instead of Statement. Not only you can
use the same SQL-Statement all the time (with ? instead
of the concrete values), it's the only way of inserting
larger blocks of data into the database (using BLOBs or
CLOBs).

In addition to this most JDBC-drivers cache the result
of the parsing of the SQL-statement, so subsequent calls
of the same statement will perform faster than the first
call.

> I don't think that there will be much difference between using statements or 
> prepared statements ... am I wrong ?

I think you're wrong.


Regards, Lothar
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Lothar Kimmeringer                E-Mail: spamfang at kimmeringer.de
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