shared_buffers
Controls the size of PostgreSQL's shared buffer cache and influences cache hit rate, checkpoint behavior, and memory pressure.
128 MB
Configuration reference
Parameters that actually drive incidents
A working index of the PostgreSQL settings that show up when something is slow, bloated, or falling over. Open any row for the full default, change-scope, tradeoffs, and verify SQL. Defaults and ranges were read from pg_settings on live PostgreSQL 18.4.
Scan the list, open a parameter for the detail. Deeper tuning walk-throughs live in the runbooks and lessons; the glossary and error catalog explain the concepts behind them.
Showing 36 of 36
work_mem
Sets per-operation memory for sorts, hashes, and similar executor nodes, so one query can consume it many times over.
4 MB
deadlock_timeout
Controls how long a backend waits while blocked on a lock before PostgreSQL runs its deadlock-detection cycle check. It does not control lock waiting itself, only when the cycle check runs.
1000 ms
lock_timeout
Aborts any statement that waits longer than this many milliseconds while trying to acquire a lock. A value of zero, the default, disables the timeout entirely, the statement then waits as long as it takes.
0 ms
statement_timeout
Aborts any statement that runs longer than this many milliseconds. A value of zero, the default, disables the timeout entirely.
0 ms
idle_in_transaction_session_timeout
Terminates a session that has an open transaction but is genuinely idle (no query in flight) for longer than this many milliseconds. A value of zero, the default, disables it.
0 ms
hash_mem_multiplier
Multiple of "work_mem" to use for hash tables.
2Any session (SET)
maintenance_work_mem
Sets the maximum memory to be used for maintenance operations.
64 MBAny session (SET)
temp_buffers
Sets the maximum number of temporary buffers used by each session.
8 MBAny session (SET)
wal_buffers
Sets the number of disk-page buffers in shared memory for WAL.
-1 8kBRestart required
default_statistics_target
Sets the default statistics target.
100Any session (SET)
effective_cache_size
Sets the planner's assumption about the total size of the data caches.
4 GBAny session (SET)
effective_io_concurrency
Number of simultaneous requests that can be handled efficiently by the disk subsystem.
16Any session (SET)
jit
Allow JIT compilation.
onAny session (SET)
random_page_cost
Sets the planner's estimate of the cost of a nonsequentially fetched disk page.
4Any session (SET)
seq_page_cost
Sets the planner's estimate of the cost of a sequentially fetched disk page.
1Any session (SET)
checkpoint_completion_target
Time spent flushing dirty buffers during checkpoint, as fraction of checkpoint interval.
0.9Reload, no restart
checkpoint_timeout
Sets the maximum time between automatic WAL checkpoints.
5 minReload, no restart
full_page_writes
Writes full pages to WAL when first modified after a checkpoint.
onReload, no restart
max_wal_size
Sets the WAL size that triggers a checkpoint.
1 GBReload, no restart
min_wal_size
Sets the minimum size to shrink the WAL to.
80 MBReload, no restart
synchronous_commit
Sets the current transaction's synchronization level.
onAny session (SET)
wal_compression
Compresses full-page writes written in WAL file with specified method.
offSuperuser · per session
wal_level
Sets the level of information written to the WAL.
replicaRestart required
autovacuum
Starts the autovacuum subprocess.
onReload, no restart
autovacuum_freeze_max_age
Age at which to autovacuum a table to prevent transaction ID wraparound.
200000000Restart required
autovacuum_naptime
Time to sleep between autovacuum runs.
1 minReload, no restart
autovacuum_vacuum_cost_limit
Vacuum cost amount available before napping, for autovacuum.
-1Reload, no restart
autovacuum_vacuum_scale_factor
Number of tuple updates or deletes prior to vacuum as a fraction of reltuples.
0.2Reload, no restart
max_locks_per_transaction
Sets the maximum number of locks per transaction.
64Restart required
max_connections
Sets the maximum number of concurrent connections.
100Restart required
hot_standby_feedback
Allows feedback from a hot standby to the primary that will avoid query conflicts.
offReload, no restart
max_wal_senders
Sets the maximum number of simultaneously running WAL sender processes.
10Restart required
wal_keep_size
Sets the size of WAL files held for standby servers.
0 MBReload, no restart
log_lock_waits
Logs long lock waits.
offSuperuser · per session
log_min_duration_statement
Sets the minimum execution time above which all statements will be logged.
-1 msSuperuser · per session