[OSM-dev] Force rendering of names/places to English only

Jukka Rahkonen jukka.rahkonen at latuviitta.fi
Wed Jun 22 14:39:01 BST 2011


Hi,

It is rather hard say how it would influence the speed in your
environment. Explain
(http://www.evolane.com/support/manuals/shared/manuals/postgresql/html/sql-explain.html)
should give you some numbers to compare and
http://developer.postgresql.org/pgdocs/postgres/planner-optimizer.html
some more background.

-Jukka Rahkonen-


M∡rtin Koppenhoefer kirjoitti:
> 2011/6/22 Peter Körner <osm-lists at mazdermind.de>:
>>> (CASE WHEN "name:en" IS NOT NULL THEN "name:en" ELSE name END) AS name
>>
>> Simpler:
>>
>> COALESCE("name:en", "name")
>>
>>
>> COALESCE selects the first none-null value from a chain.
>
>
> thank you for this Peter. Can anyone tell how much this influences the
> speed? Is it noticably slower to check a list like COALESCE("name:en",
> "name:it", "name:de", "int_name", "name") compared to a simple name
> select? Do I suppose correctly that COALESCE is faster for multiple
> keys then nested CASE WHENs ? And what about regex-s (e.g. check for
> non-latin characters and only use in these cases a different name) and
> selection speed?
>
> Cheers,
> Martin
>
> _______________________________________________
> dev mailing list
> dev at openstreetmap.org
> http://lists.openstreetmap.org/listinfo/dev
>





More information about the dev mailing list