oracular (3) SPI_cursor_open.3.gz

NAME

       SPI_cursor_open - set up a cursor using a statement 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 statement 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 statement 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 C function (it can, in fact, live to the end of the current transaction).
       Returning the portal name to the C function'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
           prepared statement (returned by SPI_prepare)

       Datum * values
           An array of actual parameter values. Must have same length as the statement's number of arguments.

       const char * nulls
           An array describing which parameters are null. Must have same length as the statement's number of
           arguments.

           If nulls is NULL then SPI_cursor_open assumes that no parameters are null. Otherwise, each entry of
           the nulls array should be ' ' if the corresponding parameter value is non-null, or 'n' if the
           corresponding parameter value is null. (In the latter case, the actual value in the corresponding
           values entry doesn't matter.) Note that nulls is not a text string, just an array: it does not need a
           '\0' terminator.

       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.