[Tile-serving] [osm2pgsql] Drop undesired tags in default.style (#46)

[Paul Norman]

> On the other hand, does anyone have an estimate of how much disk space is saved by not including them in the hstore?

The `tags hstore` column for the linestring table on errol is 17GB. Assuming most ways don't have enough tags to be TOASTed (reasonable, unless there's a *lot* of tags in which case they're probably droppable) here are some numbers

There's 13.5m tiger ways. With the droppable tiger tags, a rough estimate puts the count of 100 million tags dropped, average 15 byte key. If you assume 30 bytes total per tag that's 3GB, for a reduction of about 18% from TIGER alone. The tags index is about twice the size, and it'd reduce that too.

Yahoo is another big set, with about 40 million tags. They're not 8-bit characters, but it's a few percent.

Overall I'd guess 25%-50% of the tags hstore could be gotten of rid of.

---
Reply to this email directly or view it on GitHub:
https://github.com/openstreetmap/osm2pgsql/issues/46#issuecomment-24013448
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/tile-serving/attachments/20130907/d2e761ff/attachment.html>