Question

I have a C extension (code below) in which I’m trying to get access to a database but I’m getting the following error:


FATAL: cannot read pg_class without having selected a database at character 15


How to get around this issue? I couldn’t find out how to specify the database in the SPI API.

Similar code if run through a trigger (calling a function that accesses the same database) works just fine – obviously the database is implicit in this case.

Code follows:

static void my_function(XactEvent event, void *arg) {
char   sql[512];
switch(event) {
case XACT_EVENT_COMMIT:
  if(SPI_connect() == SPI_OK_CONNECT)
  {
    snprintf(sql, sizeof(sql), "SELECT * FROM myschema.mytable;");
    if (SPI_OK_SELECT == SPI_execute(sql, true, 0))
    {
      // Rest of code...
    }
  }

Thanks,

D.

Answer 1

The database should always be implicit, since SPI is only meant to be used by C functions called from a database session. See the example.

How do you execute this code?