Message-ID: <1e9f99f9-9cdb-4bc3-85d9-c017fbc54566@enterprisedb.com>
Date: Tue, 23 Nov 2021 17:06:32 +0100
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Subject: Re: ORDER BY in materialized view example?
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To: Maciek Sakrejda <m.sakrejda@gmail.com>, pgsql-docs@postgresql.org
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From: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
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On 23.11.21 07:18, Maciek Sakrejda wrote:
> An example in the materialized view documentation [1] includes an ORDER 
> BY clause without a clear reason. Does it help build the index more 
> efficiently? I suppose it's also sort of like a CLUSTER?
> 
> But it seems like the ORDER BY should either be explained or dropped: as 
> is, this gives the impression that the ORDER BY can be "embedded" into 
> the resulting relation and persist to other queries that do not include 
> an explicit ORDER BY. (I recently ran across this belief, though not 
> sure if this was due to this example.)
> 
> Thoughts?
> 
> [1]: 
> https://www.postgresql.org/docs/current/rules-materializedviews.html 
> <https://www.postgresql.org/docs/current/rules-materializedviews.html>

I agree the ORDER BY is not relevant to the example.  There might be 
some implementation-dependent advantage to ordering a materialized view, 
but if there is, it isn't explained in the example.