On 5/25/2016 2:32 PM, Sven Geggus wrote:
I have always been wondering if it would be possible to get rid of the
special tables used for the sole purpose of keeping the rendering database
up-to-date by using a scheme like this:
osm2pgsql database with special tables -> some psql replication scheme
--> many slave databases without special tables kept up-to date using psql
some replication scheme
This would have the advantage of a lower storage foot-print (only 4
rendering tables left).
You'd still have the full storage footprint on one machine, it just
helps with the requirements on your read-only replica slaves.
This can be done a few ways right now
- pglogical or trigger-based (e.g. slony) replication
Streaming replication doesn't work here since it replicates the entire
cluster including slim tables
- PostgreSQL FDW magic
It should be fairly easily to post-import move the rendering tables to
another cluster and use any replication method with that cluster.
- Allow connection information to be set per-table in osm2pgsql
This may be possible with the multi- backend. Adding it to all the
backends shouldn't be too hard as osm2pgsql already uses independent
connections for each table. The slim tables and rendering tables could
then be directly placed on databases on different clusters
What is not possible is to centralize this. When doing updates what goes
to the rendering tables depends on the osm2pgsql style, so your
rendering table updates will not be the same as other people with a
different style.
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