[Qgis-community-team] Materialised / Rule based views

[Tim Sutton]

Thanks Anita!

On Sat, Jan 20, 2018 at 4:10 PM, Anita Graser <anitagraser at gmx.at> wrote:

> I've changed the heading to better represent the content. See PR
> https://github.com/qgis/QGIS-Documentation/pull/2322
>
> Regards,
> Anita
>
>
>
> On Fri, Jan 12, 2018 at 10:57 AM, Andreas Neumann <a.neumann at carto.net>
> wrote:
>
>> Hi all,
>>
>> I agree with Richard. Thanks for referencing the PG docs. Normally,
>> materialized views are not meant to be manipulated (insert/update/delete).
>> They are usually used to improve performance of complex queries.
>>
>> Yes - with the power of PostgreSQL one could probably somehow also update
>> also materialized views (with rules and triggers) - but in most cases it
>> would not make sense and I wouldn't encourage it.
>>
>> Greetings,
>> Andreas
>>
>> On 2018-01-12 10:41, Richard Duivenvoorde wrote:
>>
>> Hi,
>>
>> just because I stumbled upon this last month:
>>
>> A materialized view is originally just a table based on a query. So you
>> should not update the 'view' as upon a refresh, those edits will be
>> overwritten.
>>
>> Postgresql has an 'official' materialized view
>>
>> https://www.postgresql.org/docs/9.3/static/sql-createmateria
>> lizedview.html
>>
>> which you can 'refresh' using a query:
>>
>> https://www.postgresql.org/docs/9.3/static/sql-refreshmateri
>> alizedview.html
>>
>> I think the heading in the training_manual should be something like:
>> 'rule based updates' or so?
>>
>> Regards,
>>
>> Richard Duivenvoorde
>>
>>
>>
>> On 11-01-18 23:32, Tim Sutton wrote:
>>
>> Hi
>>
>> I (or whoever wrote it) could probably have chosen a better example.
>> Materialised views change something that is normally read only (a view)
>> into something that can be treated as a writable table (with the correct
>> transactions being deferred to the tables that were used to create the
>> view). So agreed we should either change the example or the heading :-)
>>
>> Regards
>>
>> Tim
>>
>> On 11 Jan 2018, at 23:24, Anita Graser <anitagraser at gmx.at
>> <mailto:anitagraser at gmx.at>> wrote:
>>
>> Hi,
>>
>> I'm wondering about the term
>> ​"
>> Materialised Views (Rule based views)
>> ​" in the lesson about rules:​
>> ​
>> https://docs.qgis.org/testing/en/docs/training_manual/databa
>> se_concepts/rules.html
>>
>> Maybe I'm missing something, but it doesn't seem like the example has
>> anything to do with views. It's a nice rule that writes into a regular
>> table, as far as I can tell.
>>
>> It would be good to provide an example that deals with inserting data
>> into a view.
>>
>> What do you think about changing the subheading to "Creating a logging
>> rule"?
>>
>> Regards,
>> Anita
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>>
>> —
>>
>>
>>
>>
>>
>>
>> *Tim Sutton*
>>
>> *Co-founder:* Kartoza
>> *Project chair:* QGIS.org <http://QGIS.org>
>>
>> Visit http://kartoza.com <http://kartoza.com/> to find out about open
>> source:
>>
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>>
>>
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>>
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>>
>>
>


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​

Tim Sutton
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