Cursors

It is possible to do range queries using cursors.

To create a cursor the sp_cursor(), function should be used. Each call to sp_get() on cursor object makes an iteration step according to current iteration order. Second and futher sp_get() calls must using previously get object to continue iteration.

To set iteration order, cursor key object must be prepared by setting order field. To do prefix scan prefix field must be set using the same argument convention as for key. Supported orders: >, >=, <, <= both including or excluding search key. By default key order is set to >=.

If search key is not set, then maximum or minimum key is returned.

Example (traverse a database in increasing order):

void *cursor = sp_cursor(env);
void *o = sp_document(db);
sp_setstring(o, "order", ">=", 0);
while ((o = sp_get(cursor, o))) {
    char *key = sp_getstring(o, "key", NULL);
    char *value = sp_getstring(o, "value", NULL);
    printf("%s = %s\n", key, value);
}
sp_destroy(cursor);

Cursors are consistent. It is possible to do iteration and deletions or updates at the same time without any interference with query data or other transactions.

Cursor should be freed using the sp_destroy() function after usage.