GeoHashing and its use as a Tag

Hi,

A question on the subject of Geohashes and their use as a Tag : wouldn’t a 12 characters Geohash count as potential high series cardinality ? Which would force the use of shorter GeoHashes.

If so, how can collision (and overwrites) be avoided in such a scenario ?

Best Regards,
John

(Originally posted as comment but probably deserves its own thread)