SPI_cursor_open sets up a cursor
(internally, a portal) that will execute a plan prepared by
Using a cursor instead of executing the plan directly has two benefits. First, the result rows can be retrieved a few at a time, avoiding memory overrun for queries that return many rows. Second, a portal can outlive the current procedure (it can, in fact, live to the end of the current transaction). Returning the portal name to the procedure's caller provides a way of returning a row set as result.
name for portal, or NULL to let the system select a name
execution plan (returned by
actual parameter values
An array describing which parameters are null values.
n indicates a null value (entry in
values will be ignored); a space
indicates a nonnull value (entry in values is valid). If nulls is NULL then
SPI_cursor_open assumes that
no parameters are null.