Обсуждение: Need help on bytea usage

Hi,

I am trying to use bytea in postgres to store binary data such as a
structure. I used sql insert statement. I tried malloc and PQescapeBytea in
vain.

i tried palloc but get undefined references to CurrentMemoryContext and
MemoryContextAlloc. 

I am trying to find any sample code that inserts a binary data using bytea
storage type in postgres. I am using linux, and libpq libraries.

I couldnt find any sample code so far. I greatly appreciate your help in
pointing me towards some sample code that does this.

Thanks

Simon

Simon,
My reply is pretty late, maybe you've already find out on your own.
Here is what I can show you

...
struct measurestation {int Id ;char Name[NAMELEN] ;char ProviderName[NAMELEN] ;char ProviderTime[15] ;float Longitude
;floatLatitude ;int Height ;int nValue ;float Value ;int MeasureHght ;struct measurestation* next ;
 
} ;
typedef struct measurestation MeasureValues ;
...   char CmdLine[1024];   PGconn     *conn;   PGresult   *res;
   MeasureValues mval ;   char ByteaString[1024];   size_t binarylen;
   /* insert a C struct as bytea type */   memset ( &mval , 0 , sizeof(MeasureValues) ) ;   strcpy ( mval.Name ,
"stat-name") ;   strcpy ( mval.ProviderName , "prov-name" ) ;
 

/*
keep in mind libpq is not thread-safe,
so what I use as buffer 'ByteaString' should be 4 times the
sizeof(MeasureValues)
to be on the safe side (all non-printables bytes become four byte octets
\nnn)
*/   strcpy ( ByteaString , (const char *)                          PQescapeBytea((unsigned char *) &mval ,
                          sizeof(MeasureValues),
 
&binarylen));   sprintf(CmdLine, "INSERT INTO bytea_tab ( bytea_col ) VALUES
('%s');",                      ByteaString);   res = PQexec(conn, CmdLine);   if (!res || PQresultStatus(res) !=
PGRES_COMMAND_OK)  {       fprintf(stderr, "INSERT command failed\n");       PQclear(res);       exit_nicely(conn);
}

This works for me.
Regards, Christoph