Thank you guys for your input, I really appreciate.
It's a while I haven't posted on this list and be happy to get fast and
accurate answers...
As I wrote in a previous mail, I maintain a database driver for our 4GL runtime
system, allowing Informix 4gl applications to use PostgreSQL.
In this context, we have unknown SQL statements to prepare/execute, so it's
note easy to patch the SQL on the fly to add some cast clauses as Sam
suggested...
Regarding your suggestion to use libpqtypes.h:
As a dev tool provider, we cannot force our customers to rely on add-ons
or extensions. Our driver must work with a standard PostgreSQL database.
By the way,
I would also feel more comfortable if the type ids to be passed to the
paramTypes[] array would be provided in a public header file.
I don't understand why this is not published...
Many thanks,
Seb
Merlin Moncure wrote:
On Tue, May 19, 2009 at 8:17 AM, Sebastien FLAESCH <sf@xxxxxxx> wrote:
Yes, good point.
I realize now that I would have expected libpq to give me a way to specify
the exact decoration or precision of INTERVAL parameters...
As you can do with ODBC's SQLBindParameter(), where you specify the C type,
SQL type, precision/scale or length ...
I believe this is important when it comes to data type conversion (for ex,
when you want to insert a numeric/date/time into a char or the other way).
=> sort of cast, actually...
I known libpq functions like PQexecParams() or PQexecPrepared() have a
paramFormats[] parameter to specify if the buffer will hold a string
or the binary representation of the value... but that would not help
much (I don't want to deal with internal structures!).
You might want to take a look at 'libpqtypes'. It exposes the
internal formats binary formats in easy to use structures.
e.g. (in libpqtypes.h)
typedef struct
{
int years;
int mons;
int days;
int hours;
int mins;
int secs;
int usecs;
} PGinterval;
I was curious, and decided to see what happens when you inserted an
interval with the following code snippet:
PGinterval i;
memset(&i, 0, sizeof(i));
i.secs = 1000000;
PQputf(p, "%interval", &i);
PQparamExec(c, p, "insert into foo values ($1)", 0);
select * from foo;
i
-----------
277:46:40
also, libpqtypes always sends in binary which is much faster for the
date/time types.
http://libpqtypes.esilo.com/
merlin
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