LOL, Hindsight is a very good thing and often one learns these through experience.Once told off because strict ordering was not maintained, then the lesson will never be forgotten!
HTH Mich Talebzadeh, Distinguished Technologist, Solutions Architect & Engineer London United Kingdom view my Linkedin profile <https://www.linkedin.com/in/mich-talebzadeh-ph-d-5205b2/> https://en.everybodywiki.com/Mich_Talebzadeh *Disclaimer:* Use it at your own risk. Any and all responsibility for any loss, damage or destruction of data or any other property which may arise from relying on this email's technical content is explicitly disclaimed. The author will in no case be liable for any monetary damages arising from such loss, damage or destruction. On Sat, 23 Sept 2023 at 13:29, Steve Loughran <ste...@cloudera.com.invalid> wrote: > > Now, if you are ruthless it'd make sense to randomise the order of results > if someone left out the order by, to stop complacency. > > like that time sun changed the ordering that methods were returned in a > Class.listMethods() call and everyone's junit test cases failed if they'd > assumed that ordering was that of the source file -which it was until then, > even though the language spec said "no guarantees". > > People code for what works, not what is documented in places they don't > read. (this is also why anyone writing network code should really have a > flaky network connection to keep themselves honest) > > On Sat, 23 Sept 2023 at 11:00, beliefer <belie...@163.com> wrote: > >> AFAIK, The order is free whether it's SQL without spcified ORDER BY >> clause or DataFrame without sort. The behavior is consistent between them. >> >> >> >> At 2023-09-18 23:47:40, "Nicholas Chammas" <nicholas.cham...@gmail.com> >> wrote: >> >> I’ve always considered DataFrames to be logically equivalent to SQL >> tables or queries. >> >> In SQL, the result order of any query is implementation-dependent without >> an explicit ORDER BY clause. Technically, you could run `SELECT * FROM >> table;` 10 times in a row and get 10 different orderings. >> >> I thought the same applied to DataFrames, but the docstring for the >> recently added method DataFrame.offset >> <https://github.com/apache/spark/pull/40873/files#diff-4ff57282598a3b9721b8d6f8c2fea23a62e4bc3c0f1aa5444527549d1daa38baR1293-R1301> >> implies >> otherwise. >> >> This example will work fine in practice, of course. But if DataFrames are >> technically unordered without an explicit ordering clause, then in theory a >> future implementation change may result in “Bob" being the “first” row in >> the DataFrame, rather than “Tom”. That would make the example incorrect. >> >> Is that not the case? >> >> Nick >> >>
