[development] Is "SELECT * FROM ..." ok?

David Metzler metzlerd at metzlerd.com
Sat Feb 14 03:23:03 UTC 2009

I would definitely agree here.  Selecting from watchdog definitely  
deserves to have the columns listed.  Selecting from taxonomies and  
categories are the same.   But there are places in CCK and views that  
select * might be considered more appropriate.   As a developer I'd  
love to see such comments in a patch review or code review, but I  
wouldn't love to see a bunch of issues filed because someone grepped  
my code for select *.

I was really pointing out the fallacy of the select * = poor  
performance argument, and that you might do as well to find out how  
many ROWS were returned by the select statement in question, plus  
start searching for outer joins ,etc.

And don't event get me started on insert statements without column  


On Feb 13, 2009, at 7:15 AM, Morbus Iff wrote:

> I give *little* regard for performance (in this case), and  
> everything for my *expectations* and *documentation*. I could care  
> less if it's faster or not. I care more about clarity.
> David Metzler wrote:
>> Although there are merits in this argument, I wouldn't classify it  
>> as  a bug.  There's a lot of generic/abstracted data loading, and  
>> as long  as there's code at there that dynamically adds columns,  
>> select *  actually is the sanest way to do things.
>> Also, the performance costs are database dependent. Mysql may  
>> work  one way, but other db's work another.   Any DB with  
>> precompiled  cached queries is not going to carry significant  
>> parsing overhead.   The amount of data transfered in most cases is  
>> dependent on the size  of the data in the column and not the  
>> number of columns.  So in some  tables it may make sense.  You  
>> might get the name of the image file  in drupal, but you're not  
>> likely to get the image.
>> Finally in my experience, most database performance problems lie  
>> in  what is in the WHERE or JOIN, and not what's in the column list.
> -- 
> Morbus Iff ( masochism-oriented recombinant bot (unlisted series) )
> Technical: http://www.oreillynet.com/pub/au/779
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