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NAME

       SPI_cursor_open - set up a cursor using a plan created with SPI_prepare

SYNOPSIS

       Portal SPI_cursor_open(const char * name, SPIPlanPtr 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.

       The passed-in parameter data will be copied into the cursor's portal, so it can be freed
       while the cursor still exists.

ARGUMENTS

       const char * name
           name for portal, or NULL to let the system select a name

       SPIPlanPtr 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. Note there is no error return convention; any
       error will be reported via elog.