Analyzing queries with high disk IO

RDS Aurora PostgreSQL 10.14 instance db.r5.4xlarge. I'm trying to figure out some high RDS IO costs in my machine. I'm looking at the pg_stat_statements and asking whether the following query make sense: SELECT rolname::regrole, calls, round((total_time / 1000 / 60)::numeric, 3) as total_minutes, round(((total_time / 1000) / calls)::numeric, 3) as average_time_seconds, rows, userid, regexp_replace(query, '[ \t\n]+', ' ', 'g') AS query_text, 100.0 * shared_blks_hit / nullif(shared_blks_hit + shared_blks_read, 0) AS hit_percent, pg_size_pretty((shared_blks_hit + shared_blks_read) * 8192) AS total_memory_read FROM pg_stat_statements JOIN pg_roles r ON r.oid = userid WHERE calls > 1 AND rolname NOT LIKE '%backup' AND rolname 'rdsadmin' AND rolname 'rdsproxyadmin' ORDER BY 8 asc nulls last LIMIT 5; According to the document hit_percent indicate how much data was fetch from the cache (shared_buffer or os kernel) vs. the total data - the higher the number, the better... In my addition, I have total_memory_read which is the total of memory read from both disk and cache. Here is an ouput I recieve |rolname |calls|total_minutes|average_time_seconds|rows|userid|query_text |hit_percent |total_memory_read| +----------+-----+-------------+--------------------+----+------+----------------------+------------------+-----------------+ |XXX |8 |4.278 |32.085 |256 |20550 |SELECT some_query ... |44.915182913169814|420 GB | +----------+-----+-------------+--------------------+----+------+----------------------+------------------+-----------------+ My questions: 1. Does total_memory_read is really the amount of memory this 8 calls consume? It seems quite huge to be 420G 2. If I multiple (1-hit_percent) by total_memory_read do I get the number of GB it fetch from the disk (and eventually get disk IO of ~231)? 3. Are there any other suggestions on how to track high IO hogs?