Re: Question on 'SQL' tracing

Tim Bunce wrote:
> On Mon, May 12, 2008 at 05:15:34PM +0100, Martin Evans wrote:
>> Martin Evans wrote:
>>> After seeing the recent posting by Greg Sabino Mullane in subject "Log DBI 
>>> query and values with placeholders" I realised there was something else 
>>> DBD::ODBC was out of date with - tracing.
>>>
>>> DBD::ODBC does not implement its own trace flags but neither does it react 
>>> to 'SQL' tracing. If I set trace('SQL') I can see the TraceLevel is set to 
>>> 256 and I can find:
>>>
>>>     sub parse_trace_flag {
>>>         my ($h, $name) = @_;
>>>         #      0xddDDDDrL (driver, DBI, reserved, Level)
>>>         return 0x00000100 if $name eq 'SQL';
>>>         return;
>>>     }
>>>
>>> in DBI. So to test if 'SQL' is enabled we:
>>>
>>> if *DBIc_TRACE_LEVEL(imp_xxh) & 256) {blah;}
>> and also, how do I set this in Perl:
>>
>> $dbh->{TraceLevel} = 'SQL|3';
>>
>>     DBI::db=HASH(0x82ba9d4) trace level set to 0x100/3 (DBI @ 0x0/0) in DBI 
>> 1.601-ithread (pid 4574)
>>
>> $dbh->prepare(xxxx)
>>   here when I examine DBIc_TRACE_LEVEL(imp_dbh) it is 3!
>>
>> Similarly if I use:
>>
>> $h->trace($h->parse_trace_flags('SQL'))
>>
>> What am I doing wrong? I'm a little confused by this since DBD::Pg seems to 
>> expect 'SQL' to work.
> 
> I presume you've read http://search.cpan.org/~timb/DBI/DBI.pm#TRACING
> 
> What's missing is an equivalent section in the DBI::DBD docs.
> At the moment there's just a passing mention at the end of an unrelated section:
> http://search.cpan.org/~timb/DBI/lib/DBI/DBD.pm#The_dbd_drv_error_method
> 
> The short answer is that DBIc_TRACE_LEVEL only gives you the 'trace
> level' not the 'trace flags' (which you can get via DBIc_TRACE_FLAGS).
> 
> You probably want to use the fancy DBIc_TRACE macros though...
> 
> Hopefully this chunk of DBIXS.h with help:
> 
> #define DBIc_TRACE_LEVEL_MASK   0x0000000F
> #define DBIc_TRACE_FLAGS_MASK   0xFFFFFF00
> #define DBIc_TRACE_SETTINGS(imp) (DBIc_DBISTATE(imp)->debug)
> #define DBIc_TRACE_LEVEL(imp)   (DBIc_TRACE_SETTINGS(imp) & DBIc_TRACE_LEVEL_MASK)
> #define DBIc_TRACE_FLAGS(imp)   (DBIc_TRACE_SETTINGS(imp) & DBIc_TRACE_FLAGS_MASK)
> /* DBIc_TRACE_MATCHES(this, crnt): true if this 'matches' (is within) crnt
>    DBIc_TRACE_MATCHES(foo, DBIc_TRACE_SETTINGS(imp))
> */
> #define DBIc_TRACE_MATCHES(this, crnt)  \
>         (  ((crnt & DBIc_TRACE_LEVEL_MASK) >= (this & DBIc_TRACE_LEVEL_MASK)) \
>         || ((crnt & DBIc_TRACE_FLAGS_MASK)  & (this & DBIc_TRACE_FLAGS_MASK)) )
> /* DBIc_TRACE: true if flags match & DBI level>=flaglevel, or if DBI level>level
>    This is the main trace testing macro to be used by drivers.
>    (Drivers should define their own DBDtf_* macros for the top 8 bits: 0xFF000000)
>    DBIc_TRACE(imp,         0, 0, 4) = if level >= 4
>    DBIc_TRACE(imp, DBDtf_FOO, 2, 4) = if tracing DBDtf_FOO & level>=2 or level>=4
>    DBIc_TRACE(imp, DBDtf_FOO, 2, 0) = as above but never trace just due to level
> */
> #define DBIc_TRACE(imp, flags, flaglevel, level)        \
>         (  (flags && (DBIc_TRACE_FLAGS(imp) & flags) && (DBIc_TRACE_LEVEL(imp) >= flaglevel)) \
>         || (level && DBIc_TRACE_LEVEL(imp) >= level) )
> 
> Patches to DBI::DBD very welcome.
> 
> Tim.
> 
> 

Thanks Tim,

I've got the gist of that now and implemented in DBD::ODBC.
Patch for DBI::DBD on its way in the next few days.

Martin
-- 
Martin J. Evans
Easysoft Limited
http://www.easysoft.com