Incident brief
Undefined data type
Referencing a type that has not been created (or is misspelled or out of the search_path) raises this undefined-object error; 'currency' is not a built-in type.
In 10 seconds
- What
- Undefined data type
- What triggers it
- Create a table (or cast) that references a type name that does not exist.
- The fix
- Use an existing type (numeric, money, or a DOMAIN/type you have created).
- Proof
- Reproduced on PostgreSQL 18.4 → A single statement reproduces SQLSTATE 42704; the unknown type name is rejected and the LINE points at it.
The fix
What to do right now
The immediate, application-level response to this error.
- Use an existing type (numeric, money, or a DOMAIN/type you have created).
- Create the missing type/domain first, or schema-qualify it if it lives elsewhere.
-- Use an existing type (or create it first).
CREATE TABLE ledger (amount numeric);Diagnose
See it live on the server
Run these against the affected instance to confirm the diagnosis before you act.
Standard triage — not specific to this error
These are canonical PostgreSQL system-catalog queries, shown as SQL to run. No sample output is attached because this is general triage, not a captured lab transcript.This SQLSTATE does not have an error-specific live snapshot yet. These are the canonical system-catalog queries you run against the affected server to see the problem in real time — standard triage, not a reproduced transcript.
What is running right now
Active backends, how long each has been running, and what it is waiting on.
SELECT pid,
state,
wait_event_type,
wait_event,
now() - query_start AS running_for,
left(query, 80) AS query
FROM pg_stat_activity
WHERE state <> 'idle'
AND pid <> pg_backend_pid()
ORDER BY running_for DESC NULLS LAST;Who is blocking whom
Turn raw blocking PIDs into the actual queries on both sides of the wait.
SELECT blocked.pid AS blocked_pid,
blocked.query AS blocked_query,
blocking.pid AS blocking_pid,
blocking.query AS blocking_query
FROM pg_stat_activity AS blocked
JOIN LATERAL unnest(pg_blocking_pids(blocked.pid)) AS b(pid) ON true
JOIN pg_stat_activity AS blocking ON blocking.pid = b.pid
WHERE cardinality(pg_blocking_pids(blocked.pid)) > 0;Locks that are still waiting
Every lock a backend has requested but not yet been granted.
SELECT l.pid,
l.locktype,
l.mode,
l.granted,
COALESCE(c.relname, l.transactionid::text) AS object
FROM pg_locks l
LEFT JOIN pg_class c ON c.oid = l.relation
WHERE NOT l.granted
ORDER BY l.pid;Why it happens
What PostgreSQL is telling you
The mechanism behind the error, grounded in the official manual — not paraphrased.
PostgreSQL 18 Documentation — Appendix A. PostgreSQL Error Codes (Table A.1, Class 42 — Syntax Error or Access Rule Violation)
42704 → undefined_objectRead the full section on postgresql.org →
Referencing a type that does not exist
There is no type named 'currency' on the search_path, so PostgreSQL raises 'type currency does not exist'.The session continues normally
The failing statement ran outside a transaction block, so nothing was left in a bad state — the next statement in the same connection runs normally.Reproduce & verify
A real, single-session PostgreSQL reproduction
A literal transcript of SQL run against a live PostgreSQL instance in an isolated lab — the commands below are exactly what was executed.
- 1Create a table (or cast) that references a type name that does not exist.
- 2PostgreSQL resolves the type name and finds nothing matching in the search_path.
- 3The statement aborts with SQLSTATE 42704 and 'type currency does not exist'.
A migration referenced a 'currency' type that was never created, and the CREATE TABLE failed on the column definition.
-- The error is self-contained in one statement; no schema is required.
SELECT 'no schema needed' AS setup_note;CREATE TABLE ledger (amount currency);SELECT 'ok' AS session_after_error;What PostgreSQL actually returned
setup_note
------------------
no schema needed
(1 row)ERROR: type "currency" does not exist
LINE 1: CREATE TABLE ledger (amount currency);
^ session_after_error
---------------------
ok
(1 row)The table is created once the column uses an existing type.
We define the column with a real built-in type to show the table is created.
Without this
Before: an unknown type aborts
With this, tested
After: a numeric column is accepted
What Pro unlocks here
- The exact prevention SQL — copy-paste ready
- Raw psql output captured from the Docker lab
- A senior-DBA action list to take it further
- Live monitoring queries to catch it in production
- The deeper audit: fix-that-fails counterexample, GUC before/after, server-log evidence
Related & next steps
Follow the thread
Everything this error touches — jump straight to the sibling error, term, runbook, or parameter.
Verification
- Last verified
- 2026-07-24 (isolated lab, PostgreSQL 18.4)
- Reviewed by
- Verified against PostgreSQL 18.4 in an isolated lab environment
- Audit status
- reviewed