Show index progress

[mboeringa]

Despite improvements in indexing speed in recent releases of PostgreSQL, indexing remains one of the most time consuming steps of the osm2pgsql import.

It would therefor be nice if there was some form of basic indexing progress indication. This is in fact possible by querying the 'pg_stat_progress_create_index' system view of PostgreSQL, e.g. by a query something like this:

SELECT blocks_total,blocks_done FROM pg_catalog.pg_stat_progress_create_index WHERE datname = '<DATABASE>' AND relid = '<TABLE>'::regclass

I have personally used such query in a post-osm2pgsql processing task to show block progress, and it is really nice to have some indication of progress and a rough indication when something might be finished.

[mboeringa]

Note that it appears the 'pg_stat_progress_create_index' system view was only added in PG12, so any implementation should be PG version aware:

https://www.postgresql.org/docs/12/progress-reporting.html

[mboeringa]

Also related to #1780