Resolving 42P01: relation does not exist error

[TheOtherBrian1]

42P01 is a Postgres level error, that can also be found in the PostgREST error docs

42P01: relation "<some table name>" does not exist

There are a few possible causes

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Cause 1: Search path is broken in Client code

When directly accessing a table that is not in the public schema, it's important to reference the external schema explicitly in your Client code. Below is an example from the JS client:

const { data, error } = await supabase
  .schema('myschema') //<---------
  .from('mytable')
  .select()

If after calling the table directly, you get a 42501 permission denied error, then you must also expose the custom schema to the API..

For Supabase-managed schemas, such as vault and auth, these cannot be directly accessed through the DB REST API. If necessary, they can be strictly accessed through security definer functions.

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Cause 2: Search path is broken within a database function

The details are explained in this gist. To avoid issues, explicitly reference tables with their schema names in functions, or set the search_path to a specific schema.

create function hello_world()
returns text
language plpgsql
security definer set search_path = '' --<--set search path to empty quotes or a specific schema in a custom function
as $$
begin
  select * from <schema>.your_table --<---------------------ADD THE SCHEMA NAME before the table
end;
$$;

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Cause 3: Ignoring capitalization and other typos

The table could be defined as: CREATE TABLE “Hello”`. The double quotes make it case-sensitive, so it becomes essential to call the table with the appropriate title. It is possible to change the table name to be lowercase for convenience, either in the Table Editor, or with raw SQL:

ALTER TABLE "Table_name"
RENAME TO table_name;

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Cause 4: table or function actually does not exist

One may have never made the table or dropped it deliberately or accidentally. This can be quickly checked with the following query:

-- For tables
SELECT * FROM information_schema.tables
WHERE table_name ILIKE 'example_table'; --<------ Add relevant table name

-- For functions
SELECT
p.proname AS function_name,
 n.nspname AS schema_name,
 pg_get_functiondef(p.oid) AS function_definition
FROM
 pg_proc p
JOIN
 pg_namespace n ON p.pronamespace = n.oid
WHERE n.nspname IN ('public', 'your custom schema') --<------ Add other relevant schemas
ORDER BY n.nspname, p.proname;

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