[syslog-ng] Database field types -- insert fails for null values

[Liam Kirsher]

Balazs,

Thanks, I will test it out.

Liam

Balazs Scheidler wrote:
> On Tue, 2009-03-17 at 11:06 -0700, Liam Kirsher wrote:
>   
>> Balazs,
>>
>> Well, can a default value be NULL?  Would it be possible to say
>> something like
>> ${lat:-NULL}
>>
>> For lat/lng it definitely won't work, since 0/0 is a valid value --
>> but probably one we don't want -- someplace out in the Atlantic Ocean.
>>     
>
> Please try the attached patch, it adds a new option to the sql()
> destination driver: null().
>
> Whenever syslog-ng enounters a value that matches the string specified
> by null(), it will insert the NULL value.
>
> This patch has not yet been committed anywhere, but it seems to do the
> trick for me. The question is if it works for you?
>
> With this you could do something like:
>
> sql(... 
> 	columns(..., "art_id", ...) 
> 	values(..., "${UT.ART_ID:-@@NULL@@}", ...) 
> 	null("@@NULL@@")
>
> Of course the NULL value must be something that cannot happen in your
> dataset, you could perhaps use the null string, but in that case every
> empty string would be INSERTed as NULLs which I'm not sure is what you
> want.
>
> The problem is that within the SQL driver, every column is a string  and
> the value you specify is a template possible containing several macros.
> Syslog-ng currently has no way of knowing that the given field had no
> value, it only knows that the given field expanded to the zero string.
>
> With the sample above (and the patch below), if any other field would by
> accident contain the string @@NULL@@ it'd be emitted as a NULL value. I
> don't see too much of a risk here, but you never know...
>
> If this works out for you, I'm willing to integrate this patch, but
> possibly only after the 3.0.2 release was made. Which you can help by
> the way by testing the binaries that I've published recently.
>
>   
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-- 
Liam Kirsher
PGP: http://liam.numenet.com/pgp/