Beefy Boxes and Bandwidth Generously Provided by pair Networks
Perl Monk, Perl Meditation
 
PerlMonks  

Re: Re: Re: How to count rows using DBI & mysql - Performance results

by Zaxo (Archbishop)
on Jun 11, 2001 at 23:11 UTC ( #87619=note: print w/ replies, xml ) Need Help??


in reply to Re: Re: How to count rows using DBI & mysql - Performance results
in thread How to count rows using DBI & mysql - Performance results

My point was to demonstrate the property of unique indexes which prevent duplication: a safety measure. I never said to use the error for program control. In fact I didn't exhibit any DBI code at all.

In practice, with the index in place:

my $known_dep=$dbi->prepare_cached("select 1 from depends where usedby +=? and uses=?"); sub known_dep ($$) {#prototype because we have a fixed number of place +holders $known_dep->execute(@_); $known_dep->rows; # 1 or 0 for unique index. }

For frequent operations, we can improve performance with the sth->bind_params() method.

We search on an index, using a pre-prepared statement handle with placeholders. That will be fast.

I didn't mention before that NULL in multiindexes is only available in MyISAM tables.

After Compline,
Zaxo


Comment on Re: Re: Re: How to count rows using DBI & mysql - Performance results
Download Code

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://87619]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others surveying the Monastery: (7)
As of 2015-07-04 16:24 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    The top three priorities of my open tasks are (in descending order of likelihood to be worked on) ...









    Results (60 votes), past polls