How to get disk merge statistics in PostgreSQL?

Question

PostgreSQL

It would be necessary to find out how often disk merge occurs, to pull out statistics on indexes, for example, you can do this:

SELECT
  relname,
  100 * idx_scan / (seq_scan + idx_scan) percent_of_times_index_used,
  n_live_tup rows_in_table
FROM
  pg_stat_user_tables
WHERE
  seq_scan + idx_scan > 0
ORDER BY
  n_live_tup DESC;

Is it possible to extract similar data about disk merge?

Answer 1

uh, what do you mean by disk merge?
offhand... turn on track_io_timing and see pg_statio_user_tables, pg_statio_user_indexes views (blks_read/blks_hit fields).