spi_cursor_open(7)
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 execute a plan prepared by SPI_prepare. The parameters have the same meanings 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 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.
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