resultset an iterator?

[mistral]

Hello,

1)If a execute a statement : SELECT * FROM balaba.
And I retrieve this statement as a resultset. Then is this result set
totally filled with the table => the resultset contains the whole table
blabla.
OR is this just an interator and every time I do a next the database is
contacted and the next record  is retrieved.

This is important because you don't want a whole db table in your memory

2) Is the com.mysql.jdbc.resultset better than java.sql.resultset?


Thanks !


Tom

 

[Michael Borgwardt]

Hello,

1)If a execute a statement : SELECT * FROM balaba.
And I retrieve this statement as a resultset. Then is this result set
totally filled with the table => the resultset contains the whole table
blabla.
OR is this just an interator and every time I do a next the database is
contacted and the next record is retrieved.

That's an implementation detail of the JDBC driver.

This is important because you don't want a whole db table in your memory

You don't want a network roundtrip for each single row either, that would probably
be worse in most cases. A good JDBC driver should fetch the rows in reasonable
chunks (maybe 100) at a time. This is even configurable somewhere in JDBC, but
I remember reading somewhere that most JDBC drivers do indeed fetch the entire
table, and it's not that much of a problem. After all, you very rately do an
unqualified select on a really big table - what would you do with the result,
after all?

2) Is the com.mysql.jdbc.resultset better than java.sql.resultset?

I suspect that it is simply an implementation of java.sql.resultset, which
is an interface.

 

[mistral]

That's an implementation detail of the JDBC driver.


You don't want a network roundtrip for each single row either, that would
probably be worse in most cases. A good JDBC driver should fetch the rows
in reasonable chunks (maybe 100) at a time. This is even configurable
somewhere in JDBC, but I remember reading somewhere that most JDBC drivers
do indeed fetch the entire table, and it's not that much of a problem.
After all, you very rately do an unqualified select on a really big table
- what would you do with the result, after all?

I suspect that it is simply an implementation of java.sql.resultset, which
is an interface.

Ok thank you !

 

[mistral]

Hello,

1)If a execute a statement : SELECT * FROM balaba.
And I retrieve this statement as a resultset. Then is this result set
totally filled with the table => the resultset contains the whole table
blabla.
OR is this just an interator and every time I do a next the database is
contacted and the next record  is retrieved.

This is important because you don't want a whole db table in your memory


2) Is the com.mysql.jdbc.resultset better than java.sql.resultset?


Thanks !


Tom

The solution for this problem is discussed in comp.lang.java.databases.