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Re: Using a single database handle or multiple handles

by tobyink (Abbot)
on Oct 11, 2012 at 13:45 UTC ( #998446=note: print w/replies, xml ) Need Help??

in reply to Using a single database handle or multiple handles

Depends on the database. For most, a single handle is preferable.

Microsoft SQL Server (and presumably Sybase too), when connected to using the TDS libraries does not allow multiple concurrent queries to execute on the same handle. You need to finish one query before making another. Thus patterns where you do:

my $results = $dbh->someQuery; while (my $row = $results->fetchrow_array) { $dbh->someOtherQuery; }

will not work unless you open a second connection. (I think some newer versions of TDS do actually emulate concurrent queries by transparently opening a second connection when required.)

perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'

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Re^2: Using a single database handle or multiple handles
by mje (Curate) on Oct 12, 2012 at 09:40 UTC

    Newer MS SQL Server drivers (and some other commercial ones) have an attribute called MARS_Connection which when set to 1 enables Multiple Active Result Sets. However, it is generally slower and has a number of restrictions. I wrote a small article on it for DBD::ODBC at Multiple Active Statements (MAS) and DBD::ODBC.

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[robby_dobby]: marto: Oh, I see you're from an even colder north :-)
[robby_dobby]: marto: Ldn, right now
[marto]: icy here today, snow on the hills
[Corion]: Oh yes, Friday!
[Corion]: Last day at $work before 3 weeks of vacation (well, not that I'd be really travelling, but no-work-time ;) )
[robby_dobby]: marto: yeah, I'd eventually visit Glasgow some day - just to visit the home town of GHC :-)
[robby_dobby]: Corion: Oh, that's awesome! Your timing is perfect enough to see all hell break loose when you get back at work :P
[marto]: well, let me know in advance, I'll buy you a pint :)
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[robby_dobby]: marto: and, I'm not sure I'd be around here long enough for YAPC::EU

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