Function mariadb_sys::handler_ha_was_semi_consistent_read

pub unsafe extern "C" fn handler_ha_was_semi_consistent_read(
    this: *mut handler
) -> bool

In an UPDATE or DELETE, if the row under the cursor was locked by another transaction, and the engine used an optimistic read of the last committed row value under the cursor, then the engine returns 1 from this function. MySQL must NOT try to update this optimistic value. If the optimistic value does not match the WHERE condition, MySQL can decide to skip over this row. Currently only works for InnoDB. This can be used to avoid unnecessary lock waits.

If this method returns nonzero, it will also signal the storage engine that the next read will be a locking re-read of the row.