Forum OpenACS Q&A: passing db handle to proc versus opening handle inside proc...

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1: passing db handle to proc versus opening handle inside proc...
Posted by David Kuczek on 03/26/01 07:44 PM
Sometimes I really ask too many questions 😊, but....

What are the pros and cons (I really like these two words 😉) of
passing on an existing db handle to a proc versus opening a new one
inside the proc.

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2: Response to passing db handle to proc versus opening handle inside proc... (response to 1)
Posted by Brian Baquiran on 03/27/01 01:55 AM
It's usually better to pass the db handle to the proc because you can
only have one db handle per pool per thread.
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3: Response to passing db handle to proc versus opening handle inside proc... (response to 1)
Posted by Alex Sokoloff on 03/27/01 07:05 AM
You can design the proc to work with or without a handle passed to it (something we resort to a lot where I work): 

proc foo { some_variable { db "" } } {

    if {[string compare $db ""] == 0} {
        set db [ns_db gethandle subquery]
        set release 1
    } else {
        set release 0
    }

    some more code

    if {$release} {
        ns_db releasehandle $db
    }
}

This is useful because sometimes you already have a handle when you call the proc, but if you don't it's nice to have the proc handle that. I believe ACS 4 makes this irrelevant, because you use a utility that gets and releases the handle for all calls to the database.

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4: Response to passing db handle to proc versus opening handle inside proc... (response to 1)
Posted by Jonathan Ellis on 03/27/01 05:47 PM
<i>I believe ACS 4 makes this irrelevant, because you use a utility that gets and releases the handle for all calls to the database</i><br>
<br>
Correct, and if you don't want to wait, you can use the <a href="/forums/message-view?message_id=18418">backport of the ACS4 api</a> right now. :)
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5: Response to passing db handle to proc versus opening handle inside proc... (response to 1)
Posted by David Kuczek on 03/27/01 07:01 PM
Thanks a lot Jonathan. This will be a real help for us.