Step 1: Create Monitoring User

We recommend creating a separate monitoring user on your PostgreSQL database for pganalyze.

Connect to the database you will be monitoring as a PostgreSQL superuser. Then run the following to create a new user (we've generated a random password for you, but you can replace it with one of your choosing):

CREATE USER pganalyze WITH PASSWORD 'mypassword' CONNECTION LIMIT 5;
GRANT pg_monitor TO pganalyze;

CREATE SCHEMA pganalyze;
GRANT USAGE ON SCHEMA pganalyze TO pganalyze;
GRANT USAGE ON SCHEMA public TO pganalyze;

If you enable the optional reset mode (usually not required), you will also need this helper method:

CREATE OR REPLACE FUNCTION pganalyze.reset_stat_statements() RETURNS SETOF void AS
$$
  /* pganalyze-collector */ SELECT * FROM public.pg_stat_statements_reset();
$$ LANGUAGE sql VOLATILE SECURITY DEFINER;

Then, connect to each database that you plan to monitor on this server as a superuser (or equivalent) and run the following to enable the collection of additional column statistics and extended statistics:

CREATE SCHEMA IF NOT EXISTS pganalyze;
GRANT USAGE ON SCHEMA pganalyze TO pganalyze;

DROP FUNCTION IF EXISTS pganalyze.get_column_stats;
CREATE FUNCTION pganalyze.get_column_stats() RETURNS TABLE(
  schemaname name, tablename name, attname name, inherited bool, null_frac real, avg_width int, n_distinct real, correlation real
) AS $$
  /* pganalyze-collector */
  SELECT schemaname, tablename, attname, inherited, null_frac, avg_width, n_distinct, correlation
  FROM pg_catalog.pg_stats
  WHERE schemaname NOT IN ('pg_catalog', 'information_schema') AND tablename <> 'pg_subscription';
$$ LANGUAGE sql VOLATILE SECURITY DEFINER;

DROP FUNCTION IF EXISTS pganalyze.get_relation_stats_ext;
CREATE FUNCTION pganalyze.get_relation_stats_ext() RETURNS TABLE(
  statistics_schemaname text, statistics_name text,
  inherited boolean, n_distinct pg_ndistinct, dependencies pg_dependencies,
  most_common_val_nulls boolean[], most_common_freqs float8[], most_common_base_freqs float8[]
) AS
$$
  /* pganalyze-collector */ SELECT statistics_schemaname::text, statistics_name::text,
  (row_to_json(se.*)::jsonb ->> 'inherited')::boolean AS inherited, n_distinct, dependencies,
  most_common_val_nulls, most_common_freqs, most_common_base_freqs
  FROM pg_catalog.pg_stats_ext se
  WHERE schemaname NOT IN ('pg_catalog', 'information_schema') AND tablename <> 'pg_subscription';
$$ LANGUAGE sql VOLATILE SECURITY DEFINER;

Note: We never collect actual table data through this method (see the NULL values in the get_column_stats function and omitted fields like most_common_vals in the get_relation_stats_ext function), but we do collect statistics about the distribution of values in your tables. You can skip creating the get_column_stats and get_relation_stats_ext helper functions if the database contains highly sensitive information and statistics about it should not be collected. This will impact the accuracy of Index Advisor recommendations.

Note that it is important you run these as the Postgres superuser in order to pass down the full access to statistics tables.

Verify connection

Let's make sure we can connect to the database with the new user:

PGPASSWORD=mypassword psql -h localhost -d mydatabase -U pganalyze

Write down the username and password of the monitoring user, we will use it in the last step of this tutorial.

Next we continue by enabling pg_stat_statements:

Proceed to Step 2: Enabling pg_stat_statements

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