SPI_cursor_open() PostgreSQL 8.1.19 Documentation SPI_cursor_open()NAME
SPI_cursor_open - set up a cursor using a plan created with SPI_prepare
SYNOPSIS
Portal SPI_cursor_open(const char * name, void * plan,
Datum * values, const char * nulls,
bool read_only)
DESCRIPTION
SPI_cursor_open sets up a cursor (internally, a portal) that will exe‐
cute a plan prepared by SPI_prepare. The parameters have the same mean‐
ings as the corresponding parameters to SPI_execute_plan.
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 mem‐
ory 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.
ARGUMENTS
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
An array of actual parameter values. Must have same length as
the plan's number of arguments.
const char * nulls
An array describing which parameters are null. Must have same
length as the plan's number of arguments. 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.
bool read_only
true for read-only execution
RETURN VALUE
pointer to portal containing the cursor, or NULL on error
2009-12-09 SPI_cursor_open()
