Incident brief
No data found
A PL/pgSQL SELECT ... INTO STRICT found zero matching rows. PostgreSQL raised an error instead of silently leaving the target null.
In 10 seconds
- What
- No data found
- What triggers it
- Run SELECT ... INTO STRICT against a query that matches no rows.
- The fix
- Wrap the STRICT select in a BEGIN/EXCEPTION block and catch WHEN NO_DATA_FOUND if a missing row is an expected, handleable case.
- Proof
- Reproduced on PostgreSQL 16.14 → A SELECT ... INTO STRICT that matched zero rows was rejected with SQLSTATE P0002. The session was unaffected afterward.
The fix
What to do right now
The immediate, application-level response to this error.
- Wrap the STRICT select in a BEGIN/EXCEPTION block and catch WHEN NO_DATA_FOUND if a missing row is an expected, handleable case.
- Or check existence first with an ordinary (non-STRICT) SELECT INTO plus IF NOT FOUND, if you'd rather branch than raise.
BEGIN
SELECT balance INTO STRICT v_balance FROM accounts WHERE id = 999;
EXCEPTION
WHEN NO_DATA_FOUND THEN
RAISE NOTICE 'account % not found', 999;
END;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 16 Documentation — Executing a Command with a Single-Row Result (43.5.3)
If the STRICT option is specified, the command must return exactly one row or a run-time error will be reported, either NO_DATA_FOUND (no rows) or TOO_MANY_ROWS (more than one row).Read the full section on postgresql.org →
The STRICT select with zero rows
Per the manual, STRICT requires exactly one row back — zero rows raises NO_DATA_FOUND (SQLSTATE P0002) instead of silently leaving v_balance null.Confirming the session still works
The rejected block didn't affect the session — the next statement ran 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.
- 1Run SELECT ... INTO STRICT against a query that matches no rows.
- 2SQLSTATE P0002 is reported; the block aborts.
One client: a DO block runs SELECT ... INTO STRICT against a WHERE clause matching no rows.
CREATE TABLE batch7_p0002_accounts (id int PRIMARY KEY, balance numeric);DO $$
DECLARE
v_balance numeric;
BEGIN
SELECT balance INTO STRICT v_balance FROM batch7_p0002_accounts WHERE id = 999;
RAISE NOTICE 'balance = %', v_balance;
END $$;SELECT 1 AS session_still_alive;What PostgreSQL actually returned
CREATE TABLEERROR: query returned no rows
CONTEXT: PL/pgSQL function inline_code_block line 5 at SQL statement session_still_alive
---------------------
1
(1 row)The deeper lab audit for this error
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
- 2026-07-16 (Docker lab, PostgreSQL 16.14)
- Reviewed by
- Verified against PostgreSQL 16.14 in an isolated lab environment
- Audit status
- reviewed