PostgreSQL transaction timeout occurs when a transaction exceeds the configured time limit. This error prevents long-running operations and helps manage resource consumption by automatically terminating idle or overly long transactions.
Transaction timeout in PostgreSQL happens when a database transaction takes longer than the maximum allowed duration set by timeout parameters. PostgreSQL offers three main timeout mechanisms: `transaction_timeout` (PostgreSQL 17+) terminates any transaction exceeding the specified duration, `statement_timeout` terminates individual queries that run too long, and `idle_in_transaction_session_timeout` closes connections that sit idle within a transaction. These timeouts prevent resources from being locked indefinitely, avoid table bloat from long-running transactions preventing vacuuming, and protect against accidental runaway queries.
Connect to your PostgreSQL database and view the active timeout parameters. Run this query as a superuser or privileged user:
SHOW transaction_timeout;
SHOW idle_in_transaction_session_timeout;
SHOW statement_timeout;
SHOW lock_timeout;Note the values returned. A value of 0 means that timeout is disabled.
Check your application logs or PostgreSQL logs to determine which timeout parameter is causing the error. Look for error messages like:
- "FATAL: terminating connection due to transaction timeout" → transaction_timeout
- "ERROR: terminating connection due to idle-in-transaction timeout" → idle_in_transaction_session_timeout
- "ERROR: canceling statement due to statement timeout" → statement_timeout
PostgreSQL logs are typically in /var/lib/postgresql/data/log/ on Linux or can be queried from pg_log if enabled.
If the timeout is too short, increase it. Connect to your database and set the timeout at the session level before running the operation:
SET statement_timeout = '60s';
SET transaction_timeout = '600s';
SET idle_in_transaction_session_timeout = '300s';
-- Your long-running operation here
COPY table_name FROM 'large_file.csv';For permanent changes, modify postgresql.conf (not recommended globally) or set user/database-level defaults:
ALTER DATABASE mydb SET statement_timeout = '60s';
ALTER USER myuser SET statement_timeout = '60s';Instead of just increasing timeouts, optimize the operation to complete faster. For long queries:
-- Use EXPLAIN ANALYZE to identify bottlenecks
EXPLAIN ANALYZE SELECT * FROM large_table WHERE expensive_condition;
-- Add indexes if needed
CREATE INDEX idx_name ON table_name(column_name);
-- Use batching for bulk operations instead of single large transaction
BEGIN;
DELETE FROM table_name WHERE condition LIMIT 1000;
COMMIT;
BEGIN;
DELETE FROM table_name WHERE condition LIMIT 1000;
COMMIT;For migrations, break them into smaller steps or run during maintenance windows.
If the error is "idle-in-transaction timeout", the problem is your application holding transactions open without activity. Ensure your application:
1. Commits or rolls back transactions promptly
2. Doesn't leave connections idle in a transaction
3. Uses connection pooling (PgBouncer, pgpool-II) if needed
Example of bad code (left open):
conn = psycopg2.connect(...)
cursor = conn.cursor()
cursor.execute("BEGIN")
cursor.execute("SELECT ...")
# ... code does something else for 5 minutes ...
# Connection still in transaction, not committed!Fixed version:
conn = psycopg2.connect(...)
with conn:
cursor = conn.cursor()
cursor.execute("SELECT ...")
# Automatically commits on success, rolls back on errorAfter fixing the immediate issue, set sensible timeout values:
-- For most applications
ALTER SYSTEM SET statement_timeout = '30s';
ALTER SYSTEM SET idle_in_transaction_session_timeout = '60s';
-- Reload configuration
SELECT pg_reload_conf();Or in postgresql.conf:
statement_timeout = 30s
idle_in_transaction_session_timeout = 60s
transaction_timeout = 600s # PostgreSQL 17+Reload with pg_ctl reload or SELECT pg_reload_conf();
PostgreSQL 17+ includes the new transaction_timeout parameter, which applies to entire transactions (both explicit BEGIN...COMMIT and implicit single-statement transactions). This is more aggressive than statement_timeout which only applies to individual queries. If multiple timeout parameters are set, the shortest timeout takes precedence. Be cautious setting timeouts globally in postgresql.conf as it affects all sessions; prefer setting at the database or user level instead. For managed PostgreSQL services (AWS RDS, Azure Database, Google Cloud SQL), timeout limits may be set by the provider and cannot be exceeded. In high-concurrency environments, consider using connection pooling tools like PgBouncer to manage idle connections more efficiently rather than relying solely on timeout parameters.
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