SPI_scroll_cursor_fetch fetches some rows from a
cursor. This is equivalent to the SQL command FETCH.
portal containing the cursor
one of FETCH_FORWARD, FETCH_BACKWARD, FETCH_ABSOLUTE or FETCH_RELATIVE
number of rows to fetch for FETCH_FORWARD or FETCH_BACKWARD; absolute row number to fetch for FETCH_ABSOLUTE; or relative row number to fetch for FETCH_RELATIVE
See the SQL FETCH command for details of the interpretation of the direction and count parameters.
Direction values other than FETCH_FORWARD may fail if the cursor's plan was not created with the CURSOR_OPT_SCROLL option.