JDBC Internals
Hello Every body,
I am interested to know about the internal happenings of Java database connectivity. Right from start to end and also please clarify me on the following questions.
1. what happens when a database connection is created and closed?
2. What resources on the database side will be used if do not close the connection? Is it a serious problem?
3. Is it adviseable to open a connection for each request in web application? If not please let me know which technique to use.
Cheers,
Divakar
[543 byte] By [
bdsaia] at [2007-10-2 7:54:28]
> Hello Every body,
>
> I am interested to know about the internal happenings
> of Java database connectivity. Right from start to
> end and also please clarify me on the following
> questions.
Well, that would be about a very big book to cover all of that. In fact, there are already several out there....
>
> 1. what happens when a database connection is created
> and closed?
Lots and lots and lots, and it depends on which database and which driver.
> 2. What resources on the database side will be used
> if do not close the connection? Is it a serious
> problem?
It depends a lot on the particular database and driver; serious problems can result, such as causing the database to crash.
> 3. Is it adviseable to open a connection for each
> request in web application? If not please let me know
> which technique to use.
No, using a connection pool is very strongly advised. Either use the "search forums" feature, to the left, or use Google, looking for "connection pooling". Also, take a look at Apache's DBCP.
If you hanven't read the Sun JDBC tutorial yet, do that too.
http://java.sun.com/docs/books/tutorial/jdbc/
> 2. What resources on the database side will be used
> if do not close the connection? Is it a serious
> problem?
yeah, although it's not the end of the world
the connection will timeout eventually
but you should ALWAYS proactively close it
> 3. Is it adviseable to open a connection for each
> request in web application? If not please let me know
> which technique to use.
no, NEVER do that
almost all web apps support multiple users
if you are opening and closing often, you're performance will suffer
better to pool 10-25 (or whatever) connections and reuse them
when the web app shuts down, THEN you can close them
>
> Cheers,
> Divakar
