sort.md

Sort

• ⬅️️ Back

Sorting is a common operation in data processing. Thanks to implementation of External Sort algorithm, sorting as everything else is by default memory-safe. This means that even sorting 10gb file if doable in just a few megabytes of RAM.

Warning

Please remember that sort is an expensive operation, usually datasets are either loaded into destination storages, or reduced by filtering/grouping. Sorting needs to go through entire dataset and sort all Rows regardless of how big the dataset is compared to available memory. To achieve that, External Sort is using cache which relays on I/O that might become a bottleneck.

Example

<?php 

data_frame()
    ->read(from_sequence_number('id', 1, 10))
    ->sortBy(ref('id')->desc())
    ->collect()
    ->write(to_output(false))
    ->run()

Output:

+----+
| id |
+----+
| 10 |
|  9 |
|  8 |
|  7 |
|  6 |
|  5 |
|  4 |
|  3 |
|  2 |
|  1 |
+----+
10 rows