The following parameters are intended for developer testing, and
should never be used on a production database. However, some of
them can be used to assist with the recovery of severely damaged
databases. As such, they have been excluded from the sample
postgresql.conf
file. Note that many of these
parameters require special source compilation flags to work at all.
allow_in_place_tablespaces
(boolean
)
#
Allows tablespaces to be created as directories inside
pg_tblspc
, when an empty location string
is provided to the CREATE TABLESPACE
command. This
is intended to allow testing replication scenarios where primary and
standby servers are running on the same machine. Such directories
are likely to confuse backup tools that expect to find only symbolic
links in that location.
Only superusers and users with the appropriate SET
privilege can change this setting.
allow_system_table_mods
(boolean
)
#
Allows modification of the structure of system tables as well as
certain other risky actions on system tables. This is otherwise not
allowed even for superusers. Ill-advised use of this setting can
cause irretrievable data loss or seriously corrupt the database
system.
Only superusers and users with the appropriate SET
privilege can change this setting.
backtrace_functions
(string
)
#This parameter contains a comma-separated list of C function names. If an error is raised and the name of the internal C function where the error happens matches a value in the list, then a backtrace is written to the server log together with the error message. This can be used to debug specific areas of the source code.
Backtrace support is not available on all platforms, and the quality of the backtraces depends on compilation options.
Only superusers and users with the appropriate SET
privilege can change this setting.
debug_discard_caches
(integer
)
#
When set to 1
, each system catalog cache entry is
invalidated at the first possible opportunity, whether or not
anything that would render it invalid really occurred. Caching of
system catalogs is effectively disabled as a result, so the server
will run extremely slowly. Higher values run the cache invalidation
recursively, which is even slower and only useful for testing
the caching logic itself. The default value of 0
selects normal catalog caching behavior.
This parameter can be very helpful when trying to trigger
hard-to-reproduce bugs involving concurrent catalog changes, but it
is otherwise rarely needed. See the source code files
inval.c
and
pg_config_manual.h
for details.
This parameter is supported when
DISCARD_CACHES_ENABLED
was defined at compile time
(which happens automatically when using the
configure option
--enable-cassert
). In production builds, its value
will always be 0
and attempts to set it to another
value will raise an error.
debug_io_direct
(string
)
#
Ask the kernel to minimize caching effects for relation data and WAL
files using O_DIRECT
(most Unix-like systems),
F_NOCACHE
(macOS) or
FILE_FLAG_NO_BUFFERING
(Windows).
May be set to an empty string (the default) to disable use of direct
I/O, or a comma-separated list of operations that should use direct I/O.
The valid options are data
for
main data files, wal
for WAL files, and
wal_init
for WAL files when being initially
allocated.
Some operating systems and file systems do not support direct I/O, so non-default settings may be rejected at startup or cause errors.
Currently this feature reduces performance, and is intended for developer testing only.
debug_parallel_query
(enum
)
#
Allows the use of parallel queries for testing purposes even in cases
where no performance benefit is expected.
The allowed values of debug_parallel_query
are
off
(use parallel mode only when it is expected to improve
performance), on
(force parallel query for all queries
for which it is thought to be safe), and regress
(like
on
, but with additional behavior changes as explained
below).
More specifically, setting this value to on
will add
a Gather
node to the top of any query plan for which this
appears to be safe, so that the query runs inside of a parallel worker.
Even when a parallel worker is not available or cannot be used,
operations such as starting a subtransaction that would be prohibited
in a parallel query context will be prohibited unless the planner
believes that this will cause the query to fail. If failures or
unexpected results occur when this option is set, some functions used
by the query may need to be marked PARALLEL UNSAFE
(or, possibly, PARALLEL RESTRICTED
).
Setting this value to regress
has all of the same effects
as setting it to on
plus some additional effects that are
intended to facilitate automated regression testing. Normally,
messages from a parallel worker include a context line indicating that,
but a setting of regress
suppresses this line so that the
output is the same as in non-parallel execution. Also,
the Gather
nodes added to plans by this setting are hidden
in EXPLAIN
output so that the output matches what
would be obtained if this setting were turned off
.
ignore_system_indexes
(boolean
)
#Ignore system indexes when reading system tables (but still update the indexes when modifying the tables). This is useful when recovering from damaged system indexes. This parameter cannot be changed after session start.
post_auth_delay
(integer
)
#The amount of time to delay when a new server process is started, after it conducts the authentication procedure. This is intended to give developers an opportunity to attach to the server process with a debugger. If this value is specified without units, it is taken as seconds. A value of zero (the default) disables the delay. This parameter cannot be changed after session start.
pre_auth_delay
(integer
)
#
The amount of time to delay just after a
new server process is forked, before it conducts the
authentication procedure. This is intended to give developers an
opportunity to attach to the server process with a debugger to
trace down misbehavior in authentication.
If this value is specified without units, it is taken as seconds.
A value of zero (the default) disables the delay.
This parameter can only be set in the postgresql.conf
file or on the server command line.
trace_notify
(boolean
)
#
Generates a great amount of debugging output for the
LISTEN
and NOTIFY
commands. client_min_messages or
log_min_messages must be
DEBUG1
or lower to send this output to the
client or server logs, respectively.
trace_recovery_messages
(enum
)
#
Enables logging of recovery-related debugging output that otherwise
would not be logged. This parameter allows the user to override the
normal setting of log_min_messages, but only for
specific messages. This is intended for use in debugging hot standby.
Valid values are DEBUG5
, DEBUG4
,
DEBUG3
, DEBUG2
, DEBUG1
, and
LOG
. The default, LOG
, does not affect
logging decisions at all. The other values cause recovery-related
debug messages of that priority or higher to be logged as though they
had LOG
priority; for common settings of
log_min_messages
this results in unconditionally sending
them to the server log.
This parameter can only be set in the postgresql.conf
file or on the server command line.
trace_sort
(boolean
)
#
If on, emit information about resource usage during sort operations.
This parameter is only available if the TRACE_SORT
macro
was defined when PostgreSQL was compiled.
(However, TRACE_SORT
is currently defined by default.)
trace_locks
(boolean
)
#If on, emit information about lock usage. Information dumped includes the type of lock operation, the type of lock and the unique identifier of the object being locked or unlocked. Also included are bit masks for the lock types already granted on this object as well as for the lock types awaited on this object. For each lock type a count of the number of granted locks and waiting locks is also dumped as well as the totals. An example of the log file output is shown here:
LOG: LockAcquire: new: lock(0xb7acd844) id(24688,24696,0,0,0,1) grantMask(0) req(0,0,0,0,0,0,0)=0 grant(0,0,0,0,0,0,0)=0 wait(0) type(AccessShareLock) LOG: GrantLock: lock(0xb7acd844) id(24688,24696,0,0,0,1) grantMask(2) req(1,0,0,0,0,0,0)=1 grant(1,0,0,0,0,0,0)=1 wait(0) type(AccessShareLock) LOG: UnGrantLock: updated: lock(0xb7acd844) id(24688,24696,0,0,0,1) grantMask(0) req(0,0,0,0,0,0,0)=0 grant(0,0,0,0,0,0,0)=0 wait(0) type(AccessShareLock) LOG: CleanUpLock: deleting: lock(0xb7acd844) id(24688,24696,0,0,0,1) grantMask(0) req(0,0,0,0,0,0,0)=0 grant(0,0,0,0,0,0,0)=0 wait(0) type(INVALID)
Details of the structure being dumped may be found in
src/include/storage/lock.h
.
This parameter is only available if the LOCK_DEBUG
macro was defined when PostgreSQL was
compiled.
trace_lwlocks
(boolean
)
#If on, emit information about lightweight lock usage. Lightweight locks are intended primarily to provide mutual exclusion of access to shared-memory data structures.
This parameter is only available if the LOCK_DEBUG
macro was defined when PostgreSQL was
compiled.
trace_userlocks
(boolean
)
#
If on, emit information about user lock usage. Output is the same
as for trace_locks
, only for advisory locks.
This parameter is only available if the LOCK_DEBUG
macro was defined when PostgreSQL was
compiled.
trace_lock_oidmin
(integer
)
#If set, do not trace locks for tables below this OID (used to avoid output on system tables).
This parameter is only available if the LOCK_DEBUG
macro was defined when PostgreSQL was
compiled.
trace_lock_table
(integer
)
#Unconditionally trace locks on this table (OID).
This parameter is only available if the LOCK_DEBUG
macro was defined when PostgreSQL was
compiled.
debug_deadlocks
(boolean
)
#If set, dumps information about all current locks when a deadlock timeout occurs.
This parameter is only available if the LOCK_DEBUG
macro was defined when PostgreSQL was
compiled.
log_btree_build_stats
(boolean
)
#If set, logs system resource usage statistics (memory and CPU) on various B-tree operations.
This parameter is only available if the BTREE_BUILD_STATS
macro was defined when PostgreSQL was
compiled.
wal_consistency_checking
(string
)
#This parameter is intended to be used to check for bugs in the WAL redo routines. When enabled, full-page images of any buffers modified in conjunction with the WAL record are added to the record. If the record is subsequently replayed, the system will first apply each record and then test whether the buffers modified by the record match the stored images. In certain cases (such as hint bits), minor variations are acceptable, and will be ignored. Any unexpected differences will result in a fatal error, terminating recovery.
The default value of this setting is the empty string, which disables
the feature. It can be set to all
to check all
records, or to a comma-separated list of resource managers to check
only records originating from those resource managers. Currently,
the supported resource managers are heap
,
heap2
, btree
, hash
,
gin
, gist
, sequence
,
spgist
, brin
, and generic
.
Extensions may define additional resource managers. Only superusers and users with
the appropriate SET
privilege can change this setting.
wal_debug
(boolean
)
#
If on, emit WAL-related debugging output. This parameter is
only available if the WAL_DEBUG
macro was
defined when PostgreSQL was
compiled.
ignore_checksum_failure
(boolean
)
#Only has effect if data checksums are enabled.
Detection of a checksum failure during a read normally causes
PostgreSQL to report an error, aborting the current
transaction. Setting ignore_checksum_failure
to on causes
the system to ignore the failure (but still report a warning), and
continue processing. This behavior may cause crashes, propagate
or hide corruption, or other serious problems. However, it may allow
you to get past the error and retrieve undamaged tuples that might still be
present in the table if the block header is still sane. If the header is
corrupt an error will be reported even if this option is enabled. The
default setting is off
.
Only superusers and users with the appropriate SET
privilege can change this setting.
zero_damaged_pages
(boolean
)
#
Detection of a damaged page header normally causes
PostgreSQL to report an error, aborting the current
transaction. Setting zero_damaged_pages
to on causes
the system to instead report a warning, zero out the damaged
page in memory, and continue processing. This behavior will destroy data,
namely all the rows on the damaged page. However, it does allow you to get
past the error and retrieve rows from any undamaged pages that might
be present in the table. It is useful for recovering data if
corruption has occurred due to a hardware or software error. You should
generally not set this on until you have given up hope of recovering
data from the damaged pages of a table. Zeroed-out pages are not
forced to disk so it is recommended to recreate the table or
the index before turning this parameter off again. The
default setting is off
.
Only superusers and users with the appropriate SET
privilege can change this setting.
ignore_invalid_pages
(boolean
)
#
If set to off
(the default), detection of
WAL records having references to invalid pages during
recovery causes PostgreSQL to
raise a PANIC-level error, aborting the recovery. Setting
ignore_invalid_pages
to on
causes the system to ignore invalid page references in WAL records
(but still report a warning), and continue the recovery.
This behavior may cause crashes, data loss,
propagate or hide corruption, or other serious problems.
However, it may allow you to get past the PANIC-level error,
to finish the recovery, and to cause the server to start up.
The parameter can only be set at server start. It only has effect
during recovery or in standby mode.
jit_debugging_support
(boolean
)
#
If LLVM has the required functionality, register generated functions
with GDB. This makes debugging easier.
The default setting is off
.
This parameter can only be set at server start.
jit_dump_bitcode
(boolean
)
#
Writes the generated LLVM IR out to the
file system, inside data_directory. This is only
useful for working on the internals of the JIT implementation.
The default setting is off
.
Only superusers and users with the appropriate SET
privilege can change this setting.
jit_expressions
(boolean
)
#
Determines whether expressions are JIT compiled, when JIT compilation
is activated (see Section 32.2). The default is
on
.
jit_profiling_support
(boolean
)
#
If LLVM has the required functionality, emit the data needed to allow
perf to profile functions generated by JIT.
This writes out files to ~/.debug/jit/
; the
user is responsible for performing cleanup when desired.
The default setting is off
.
This parameter can only be set at server start.
jit_tuple_deforming
(boolean
)
#
Determines whether tuple deforming is JIT compiled, when JIT
compilation is activated (see Section 32.2).
The default is on
.
remove_temp_files_after_crash
(boolean
)
#
When set to on
, which is the default,
PostgreSQL will automatically remove
temporary files after a backend crash. If disabled, the files will be
retained and may be used for debugging, for example. Repeated crashes
may however result in accumulation of useless files. This parameter
can only be set in the postgresql.conf
file or on
the server command line.
send_abort_for_crash
(boolean
)
#
By default, after a backend crash the postmaster will stop remaining
child processes by sending them SIGQUIT
signals, which permits them to exit more-or-less gracefully. When
this option is set to on
,
SIGABRT is sent instead. That normally
results in production of a core dump file for each such child
process.
This can be handy for investigating the states of other processes
after a crash. It can also consume lots of disk space in the event
of repeated crashes, so do not enable this on systems you are not
monitoring carefully.
Beware that no support exists for cleaning up the core file(s)
automatically.
This parameter can only be set in
the postgresql.conf
file or on the server
command line.
send_abort_for_kill
(boolean
)
#
By default, after attempting to stop a child process with
SIGQUIT, the postmaster will wait five
seconds and then send SIGKILL to force
immediate termination. When this option is set
to on
, SIGABRT is sent
instead of SIGKILL. That normally results
in production of a core dump file for each such child process.
This can be handy for investigating the states
of “stuck” child processes. It can also consume lots
of disk space in the event of repeated crashes, so do not enable
this on systems you are not monitoring carefully.
Beware that no support exists for cleaning up the core file(s)
automatically.
This parameter can only be set in
the postgresql.conf
file or on the server
command line.
debug_logical_replication_streaming
(enum
)
#
The allowed values are buffered
and
immediate
. The default is buffered
.
This parameter is intended to be used to test logical decoding and
replication of large transactions. The effect of
debug_logical_replication_streaming
is different for the
publisher and subscriber:
On the publisher side, debug_logical_replication_streaming
allows streaming or serializing changes immediately in logical decoding.
When set to immediate
, stream each change if the
streaming
option of
CREATE SUBSCRIPTION
is enabled, otherwise, serialize each change. When set to
buffered
, the decoding will stream or serialize
changes when logical_decoding_work_mem
is reached.
On the subscriber side, if the streaming
option is set to
parallel
, debug_logical_replication_streaming
can be used to direct the leader apply worker to send changes to the
shared memory queue or to serialize all changes to the file. When set to
buffered
, the leader sends changes to parallel apply
workers via a shared memory queue. When set to
immediate
, the leader serializes all changes to files
and notifies the parallel apply workers to read and apply them at the
end of the transaction.