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 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