postgres_exporter collected metric was collected before with the same name and label values

What did you do?

I started postgres-exporter using following docker-compose file:

  postgres-exporter:
    container_name: postgres-exporter
    image: prometheuscommunity/postgres-exporter
    environment:
      - DATA_SOURCE_NAME=postgresql://user:password@host:port/my_database  # I changed this for issue purpose 
    command:
      # - "--disable-default-metrics"  # doesn't matter if I run it with or without this argument 
      - "--collector.stat_statements"  # error: collected before with the same name and label values
    ports:
      - "9187:9187"

What did you expect to see?

Opening http://127.0.0.1:9187/metrics I expected to see all metrics including statements.

What did you see instead? Under which circumstances?

I see 120 errors instead, but only when using --collector.stat_statements:

An error has occurred while serving metrics:

120 error(s) occurred:
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:145094}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:1382.6511825559967}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:435282}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:145185}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:55.34379315600012}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:871110}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:2.173387e+06}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:47.36949219000851}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:145185}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:33.97874588199985}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:290354}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:431657}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:32.00555152200009}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:1.294971e+06}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:145185}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:22.935943721999884}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:145185}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:2.173386e+06}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:19.923873926997413}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:2.173386e+06}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:145185}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:16.86972648199979}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:145185}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:430448}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:11.949401952000116}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:430448}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:2.173387e+06}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:9.745451962989884}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:2.173387e+06}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:145185}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:8.085575071000099}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:1.016295e+06}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:430450}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:7.9014078029997465}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:1.297141e+06}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:290370}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:5.888327989999761}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:51}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:5.648648003}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:51}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:585396}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:5.033520371000066}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:585396}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:290370}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:4.884215216999991}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:142092}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:4.015534736999865}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:145185}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:3.905134878999939}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:725925}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:72344}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:3.298348626000012}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:145663}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:51}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:3.278106381000001}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:51}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:145185}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:3.211697052999987}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:145185}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:52}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:2.730091644}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:52}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:51}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:2.6115781110000005}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:51}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"_updb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"_updb"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:145185}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:1.297608032999997}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:145185}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"defaultdb"}  label:{name:"queryid"  value:"unknown"}  label:{name:"user"  value:"postgres"}  counter:{value:0}} was collected before with the same name and label values

Environment

System information:

I tried on 2 systems:

my MacBooks: Darwin 22.5.0 arm64
my Linux server: Linux 5.10.0-18-amd64 x86_64

postgres_exporter version:

postgres_exporter, version 0.15.0 (branch: HEAD, revision: 68c176b8833b7580bf847cecf60f8e0ad5923f9a) build user: root@7c5a76bc737a build date: 20231027-14:38:04 go version: go1.21.3 platform: linux/arm64 tags: unknown

postgres_exporter flags:

collector.stat_statements

PostgreSQL version:

14.10.0

Logs:

ts=2024-01-22T15:07:02.463Z caller=main.go:86 level=warn msg="Error loading config" err="Error opening config file \"postgres_exporter.yml\": open postgres_exporter.yml: no such file or directory"
ts=2024-01-22T15:07:02.464Z caller=proc.go:267 msg="Excluded databases" databases="[\"template0 template1 _updb defaultdb\"]"
ts=2024-01-22T15:07:02.464Z caller=main.go:103 level=warn msg="Scraping additional databases via auto discovery is DEPRECATED"
ts=2024-01-22T15:07:02.472Z caller=tls_config.go:274 level=info msg="Listening on" address=[::]:9187
ts=2024-01-22T15:07:02.472Z caller=tls_config.go:277 level=info msg="TLS is disabled." http2=false address=[::]:9187
ts=2024-01-22T15:07:02.946Z caller=server.go:74 level=info msg="Established new database connection" fingerprint=host:port
ts=2024-01-22T15:07:03.243Z caller=postgres_exporter.go:613 level=info msg="Semantic version changed" server=host:port from=0.0.0 to=14.10.0

(I changed host and port for issue purpose)

Jan 22 '24 15:01 eriktelepovsky

I am having almost the same issue.

An error has occurred while serving metrics:

5 error(s) occurred:
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"mydb"}  label:{name:"queryid"  value:"996906246641985132"}  label:{name:"user"  value:"mydbuser"}  counter:{value:1}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"mydb"}  label:{name:"queryid"  value:"996906246641985132"}  label:{name:"user"  value:"mydbuser"}  counter:{value:0.00079746}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"mydb"}  label:{name:"queryid"  value:"996906246641985132"}  label:{name:"user"  value:"mydbuser"}  counter:{value:74}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"mydb"}  label:{name:"queryid"  value:"996906246641985132"}  label:{name:"user"  value:"mydbuser"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"mydb"}  label:{name:"queryid"  value:"996906246641985132"}  label:{name:"user"  value:"mydbuser"}  counter:{value:0}} was collected before with the same name and label values

Mine has a value in the label queryid.

I am running the exporter with Docker Compose;

version: '3'
services:
  postgres-exporter:
    image: quay.io/prometheuscommunity/postgres-exporter
    ports:
      - "9187:9187"
    environment:
      DATA_SOURCE_NAME: "postgresql://postgres_exporter:mypass@postgres:5432/mydb?sslmode=disable"
    command: --web.listen-address=:9187 --web.telemetry-path=/metrics --collector.database_wraparound --collector.long_running_transactions --collector.postmaster --collector.process_idle --collector.stat_activity_autovacuum --collector.stat_statements --collector.stat_wal_receiver --collector.statio_user_indexes

Feb 01 '24 13:02 hajali-amine

same issue here -

curl localhost:26058/metrics

* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"mydb"}  label:{name:"queryid"  value:"-2355316157827874919"}  label:{name:"user"  value:"mydb_so"}  counter:{value:2}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"mydb"}  label:{name:"queryid"  value:"-2355316157827874919"}  label:{name:"user"  value:"mydb_so"}  counter:{value:5.981075956000001}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"mydb"}  label:{name:"queryid"  value:"-2355316157827874919"}  label:{name:"user"  value:"mydb_so"}  counter:{value:8}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"mydb"}  label:{name:"queryid"  value:"-2355316157827874919"}  label:{name:"user"  value:"mydb_so"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"mydb"}  label:{name:"queryid"  value:"-2355316157827874919"}  label:{name:"user"  value:"mydb_so"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_calls_total" { label:{name:"datname"  value:"mydb"}  label:{name:"queryid"  value:"-3686023444609730445"}  label:{name:"user"  value:"mydb_so"}  counter:{value:2}} was collected before with the same name and label values
* collected metric "pg_stat_statements_seconds_total" { label:{name:"datname"  value:"mydb"}  label:{name:"queryid"  value:"-3686023444609730445"}  label:{name:"user"  value:"mydb_so"}  counter:{value:5.831786688}} was collected before with the same name and label values
* collected metric "pg_stat_statements_rows_total" { label:{name:"datname"  value:"mydb"}  label:{name:"queryid"  value:"-3686023444609730445"}  label:{name:"user"  value:"mydb_so"}  counter:{value:8}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_read_seconds_total" { label:{name:"datname"  value:"mydb"}  label:{name:"queryid"  value:"-3686023444609730445"}  label:{name:"user"  value:"mydb_so"}  counter:{value:0}} was collected before with the same name and label values
* collected metric "pg_stat_statements_block_write_seconds_total" { label:{name:"datname"  value:"mydb"}  label:{name:"queryid"  value:"-3686023444609730445"}  label:{name:"user"  value:"mydb_so"}  counter:{value:0}} was collected before with the same name and label values

Feb 20 '24 16:02 acharbha

Let me explain the potential root cause for this problem.

pg_stat_statements: doesnt hold the unique key constraint on the queryid column. however the pg_stat_statements is designed in such a way that the query and the underlying subquery on a nested query will have the same query id (or) transactions that are nested on same block will have the same query id. This is basically a computed hash identifier generated by postgres pg_stat_statements that are fetched from the query sent to planner and executor.
postgres exporter: So now the exporter is collecting the metrics. say when you simulate running a nested queries which has joins, cross joins, lateral joins and so on.
Labels: Since the metrics are scrapped with labels ( user, databasename, queryid ). It is expected to have this error.
How, ever there is a fix which can be implemented. i have submitted a PR which holds the change CLICK HERE FOR PR.

Hope this explains the situation dealing with the problem.

Note: if you are using custom prometheus code with customized labels.. then you need to change the labels accordingly in the PSQL queries.

Feb 22 '24 18:02 vigneshkumar2016

I had the same issue when I defined 2 connection strings in DATA_SOURCE_NAME. Helm chart values states that I can do that. I removed 1 string and everything became fine.

Jun 20 '24 13:06 volcano1111

I have the same problem. It seems to me that this can be solved by adding the "planid" label

I added the planid label to the stat_statements collector. So far, there are no more errors.

Mar 07 '25 10:03 pavel-mokrushin

I have the same problem. It seems to me that this can be solved by adding the "planid" label

I added the planid label to the stat_statements collector. So far, there are no more errors.

did you build fixed version yourself?

Jun 30 '25 12:06 Ganji00

I have the same problem. It seems to me that this can be solved by adding the "planid" label I added the planid label to the stat_statements collector. So far, there are no more errors.

did you build fixed version yourself?

Yes, I have compiled an installation package for myself.

Jun 30 '25 12:06 pavel-mokrushin

Got the same issue. Not sure if relevant, but on low load the error is not present.

I tried the .planid fix from @pavel-mokrushin , it does not work with current version as it is seems to be either a feature for a future version or a extension: https://wiki.postgresql.org/wiki/Plan_ID_Jumbling https://github.com/legrandlegrand/pg_stat_sql_plans

Jul 08 '25 09:07 elfranne

This PR has to be merged.. unless it merged you won't be seeing this in effect.. you can contact the maintainer.. I'm using the proposed solution as per in my PR on custom image..

Sent from Outlook for Androidhttps://aka.ms/AAb9ysg

From: Elfranne @.> Sent: Tuesday, July 8, 2025 2:36:53 PM To: prometheus-community/postgres_exporter @.> Cc: VigneshViggu @.>; Comment @.> Subject: Re: [prometheus-community/postgres_exporter] collected metric was collected before with the same name and label values (Issue #998)

[https://avatars.githubusercontent.com/u/861038?s=20&v=4]elfranne left a comment (prometheus-community/postgres_exporter#998)https://github.com/prometheus-community/postgres_exporter/issues/998#issuecomment-3048017377

Got the same issue. Not sure if relevant, but on low load the error is not present.

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Jul 13 '25 14:07 vigneshkumar2016