SPI_connect opens a connection
from a procedure invocation to the SPI manager. You must call
this function if you want to execute commands through SPI. Some
utility SPI functions can be called from unconnected
procedures.
If your procedure is already connected, SPI_connect will return the error code
SPI_ERROR_CONNECT. This could
happen if a procedure that has called SPI_connect directly calls another procedure
that calls SPI_connect. While
recursive calls to the SPI
manager are permitted when an SQL command called through SPI
invokes another function that uses SPI, directly nested calls to SPI_connect and SPI_finish are forbidden. (But see SPI_push and SPI_pop.)