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Thread: Help with SPI...

Help with SPI...

From
"Cristian Prieto"
Date:
Hi, I will try to explain the most possible my question:
 
I'm writing a Store Procedure as a C Language Function in the Database, I need to handle a bytea (binary objetc) and store it in a modified mode in the database, I've done it in the following way:
 
PG_FUNCTION_INFO_V1(myspi);
 
Datum
myspi(PG_FUNCTION_ARGS)
{
 int ret;
 bool isnull;
 bytea *val;
 
 ret = SPI_connect();
 
 ret = SPI_exec("SELECT val FROM binary_table", 1);
 if (ret == SPI_OK_SELECT && SPI_processed > 0) {
    TupleDesc tupdesc = SPI_tuptable->tupdesc;
    SPITupleTable *tuptable = SPI_tuptable;
 
    val = DatumGetByteP(SPI_getbinval(tuptable->vals[0], tupdesc, 1, &isnull));
 }
 
/* Here I use and modified the new version of the val value */
 
// I don't know what to do here to store the new value again :(
 
 SPI_finish();
 PG_RETURN_INT32(val);
}
 
Well, the new value is really the content of a memory segment, I know I could store it again using SPI and an UPDATE statement, but that means that I need to transform the val value into a string, and I don't know the length of the string with the scape characters added.
 
Any idea in how to handle this?
 
Thanks a lot...
 

Re: Help with SPI...

From
Michael Fuhr
Date:
On Tue, Aug 30, 2005 at 01:28:11PM -0600, Cristian Prieto wrote:
> Well, the new value is really the content of a memory segment, I
> know I could store it again using SPI and an UPDATE statement, but
> that means that I need to transform the val value into a string,
> and I don't know the length of the string with the scape characters
> added.

You could use SPI_prepare() and SPI_execp() without having to
transform the bytea value into a string; see the SPI documentation
and look around for examples that use numbered parameters ($1, $2,
etc.).

--
Michael Fuhr