Database

Debugging and monitoring

The Supabase CLI comes with a range of tools to help inspect your Postgres instances for potential issues. The CLI gets the information from Postgres internals. Therefore, most tools provided are compatible with any Postgres databases regardless if they are a Supabase project or not.

You can find installation instructions for the the Supabase CLI here.

The inspect db command

The inspection tools for your Postgres database are under then inspect db command. You can get a full list of available commands by running supabase inspect db help.


_12
$ supabase inspect db help
_12
Tools to inspect your Supabase database
_12
_12
Usage:
_12
supabase inspect db [command]
_12
_12
Available Commands:
_12
bloat Estimates space allocated to a relation that is full of dead tuples
_12
blocking Show queries that are holding locks and the queries that are waiting for them to be released
_12
cache-hit Show cache hit rates for tables and indices
_12
_12
...

Connect to any Postgres database

Most inspection commands are Postgres agnostic. You can run inspection routines on any Postgres database even if it is not a Supabase project by providing a connection string via --db-url.

For example you can connect to your local Postgres instance:


_10
supabase --db-url postgresql://postgres:postgres@localhost:5432/postgres inspect db bloat

Connect to a Supabase instance

Working with Supabase, you can link the Supabase CLI with your project:


_10
supabase link --project-ref <project-id>

Then the CLI will automatically connect to your Supabase project whenever you are in the project folder and you no longer need to provide —db-url.

Inspection commands

Below are the db inspection commands provided, grouped by different use cases.

Disk storage

These commands are handy if you are running low on disk storage:

Query performance

The commands below are useful if your Postgres database consumes a lot of resources like CPU, RAM or Disk IO. You can also use them to investigate slow queries.

  • cache-hit - shows how efficient your cache usage is overall
  • unused-indexes - shows indexes with low index scans
  • index-usage - shows information about the efficiency of indexes
  • seq-scans - show number of sequential scans recorded against all tables
  • long-running-queries - shows long running queries that are executing right now
  • outliers - shows queries with high execution time but low call count and queries with high proportion of execution time spent on synchronous I/O

Locks

  • locks - shows statements which have taken out an exclusive lock on a relation
  • blocking - shows statements that are waiting for locks to be released

Connections

  • role-connections - shows number of active connections for all database roles (Supabase-specific command)
  • replication-slots - shows information about replication slots on the database

Notes on pg_stat_statements

Following commands require pg_stat_statements to be enabled: calls, locks, cache-hit, blocking, unused-indexes, index-usage, bloat, outliers, table-record-counts, replication-slots, seq-scans, vacuum-stats, long-running-queries.

When using pg_stat_statements also take note that it only stores the latest 5,000 statements. Moreover, consider resetting the analysis after optimizing any queries by running select pg_stat_statements_reset();

Learn more about pg_stats here.

Acknowledgements

Supabase CLI's inspect commands are heavily inspired by the pg-extras tools.