Clarify the ordering guarantees in combining queries (or lack thereof)

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От Shay Rojansky
Тема Clarify the ordering guarantees in combining queries (or lack thereof)
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Msg-id CADT4RqD0oWGCeSdGtN3UEH21HxF=1Svbr3dvEL9ueuEr-x5L4g@mail.gmail.com
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Ответы Re: Clarify the ordering guarantees in combining queries (or lack thereof)  ("David G. Johnston" <david.g.johnston@gmail.com>)
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Greetings.

I was trying to understand what - if any - are the guarantees with regards to ordering for combining queries (UNION/UNION ALL/...). From this message[1], it seems that UNION ALL does preserve the ordering of the operand queries, whereas UNION does not (presumably neither do INTERSECT, INTERSECT ALL, EXCEPT and EXCEPT ALL).

The documentation[2] makes no mention of this, I'd suggest adding a note clarifying this.

Thanks,

Shay

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