[Tile-serving] Hstore benchmarking results

[Frank Broniewski]

Am 2014-03-06 17:56, schrieb Paul Norman:
> Keep in mind that GIN indexes are very slow to build, and that to 
> Properly use hstore you need to rewrite queries (i.e. WHERE NOT 
>  tags?'foo' rather than WHERE tags->'foo' IS NULL)

Yeah, I have my own style, so I am writing my queries anyways as new
queries. My rendering chain differs also from the standard chain as I am
more interested in a  GIS / OGC compliant output than tiles ...

tags ? 'foo' is luckily not the only query that uses an index. The
following query is also nice:
tags ?| ARRAY['aeroway', 'landuse', 'natural', 'leisure', 'highway',
'amenity', 'waterway']
I use it in CartoCSS / Tilemill for styling one of the base layer and
creating the land usage "feeling" for my map.

> 
> Partial indexes are a bit more of a pain to define as well, and partial
> indexes are important for getting performance.
That is a good point, I guess I should investigate that a bit more ...

> None of this changes that --hstore-all probably isn't what you should be
> using, it's --hstore with a slimmer .style.
> 
>> I was also already thinking of removing most columns from the style
>> file and only leaving those which are always used and don't require an
>> index, like name for example.
> 
> This is on my to-benchmark list, and I think the import finished overnight.

I tried this yesterday, and maybe due to my incomplete knowledge about
the right syntax, I encountered some issues. I commented out almost all
column settings in the default style except for area, z_order and
way_area. I ran the import with --hstore-all and got differences
concerning the created polygons and linestrings. Now, after a new day, I
guess I should have changed the polygon flag to phstore instead of
commenting that out.

Just like Sven I use views for simulating columns if required. E.g.
Quantum GIS can't use a hstore column, so in order to make meaningful
queries I need to work around that.


-- 
Frank BRONIEWSKI

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