Provided by: postgresql-doc-10_10.3-1_all
SPI_cursor_open - set up a cursor using a statement created with SPI_prepare
Portal SPI_cursor_open(const char * name, SPIPlanPtr plan, Datum * values, const char * nulls, bool read_only)
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 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.
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
Pointer to portal containing the cursor. Note there is no error return convention; any error will be reported via elog.