Re: outOfMemoryError - Dirk Hillbrecht - com.mysql.lists.java

12 messages in com.mysql.lists.javaRe: outOfMemoryError

From	Sent On	Attachments
danilo	24 Jun 2003 03:02
Dirk Hillbrecht	24 Jun 2003 03:07
dr.ahab	24 Jun 2003 03:18
Jeff Mathis	24 Jun 2003 08:31
danilo	25 Jun 2003 08:28
Mark Matthews	25 Jun 2003 08:49
Jeff Mathis	25 Jun 2003 08:55
Dirk Hillbrecht	25 Jun 2003 09:17
danilo	25 Jun 2003 09:52
Mark Matthews	25 Jun 2003 10:06
Shankar Unni	25 Jun 2003 10:09
Dirk Hillbrecht	25 Jun 2003 10:36

Subject:	Re: outOfMemoryError
From:	Dirk Hillbrecht (dh...@cantamen.de)
Date:	06/25/2003 10:36:39 AM
List:	com.mysql.lists.java

Hi,

[@list: please protest if too off-topic. I would assume this is of general interest as it covers some basic and important design issues on working with databases]

danilo schrieb:

The idea of retrieving only the visible part of table does not fit my needs, because after filling the table I have to do some analisys on it's contents (calculate the sum of each row/column, percentage of each value respect the total), so I need all that stuff at once.!! So (Unlucky) I still have no friend called LIMIT !! ;)

But you have other friends. Perhaps the most important ones here: "SELECT sum(rowname)", "GROUP BY" and "HAVING".

Generally spoken it is simple: If you have to do large computations on the tables in your database, let the database do them. Always(*). If you cannot perform a certain calculation by SELECTing some way or the other, your database design is broken(**).

So, your application should

- let the database compute whatever you need.

- take these values.

- finally combine all the stuff from the database in your GUI.

I already draw the table only once at the end of the query (at least I THINK I do it, what did you mean? looping on all the ResultSet record all at once? if so I did it in that way)

Err... With "draw" you mean doing something like "tablemodel.setData()" or "jtable.setModel()", don't you? You do not call "table.redraw()" or something like this, do you?

Best regards, Dirk