SPI_cursor_open
Nome
SPI_cursor_open -- set up a cursor using a plan created with
SPI_prepare
Sinopse
Portal SPI_cursor_open(const char * name, void * plan, Datum * values, const char * nulls)
Descrição
SPI_cursor_open sets up a cursor (internally, a portal) that will execute a plan prepared by SPI_prepare.
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.
Argumentos
- const char * name
-
name for portal, or NULL to let the system select a name
- void * plan
-
execution plan (returned by
SPI_prepare)
- Datum * values
-
actual parameter values
- const char *nulls
-
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.
Valor retornado
pointer to portal containing the cursor, or NULL on error