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postgresql/src/include/pg_config_manual.h

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/*------------------------------------------------------------------------
* PostgreSQL manual configuration settings
*
* This file contains various configuration symbols and limits. In
* all cases, changing them is only useful in very rare situations or
* for developers. If you edit any of these, be sure to do a *full*
* rebuild (and an initdb if noted).
*
* Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/pg_config_manual.h
*------------------------------------------------------------------------
*/
/*
* This is the default value for wal_segment_size to be used when initdb is run
* without the --wal-segsize option. It must be a valid segment size.
*/
#define DEFAULT_XLOG_SEG_SIZE (16*1024*1024)
/*
* Maximum length for identifiers (e.g. table names, column names,
* function names). Names actually are limited to one fewer byte than this,
* because the length must include a trailing zero byte.
*
* Changing this requires an initdb.
*/
#define NAMEDATALEN 64
/*
* Maximum number of arguments to a function.
*
* The minimum value is 8 (GIN indexes use 8-argument support functions).
* The maximum possible value is around 600 (limited by index tuple size in
* pg_proc's index; BLCKSZ larger than 8K would allow more). Values larger
* than needed will waste memory and processing time, but do not directly
* cost disk space.
*
* Changing this does not require an initdb, but it does require a full
* backend recompile (including any user-defined C functions).
*/
#define FUNC_MAX_ARGS 100
/*
* When creating a product derived from PostgreSQL with changes that cause
* incompatibilities for loadable modules, it is recommended to change this
* string so that dfmgr.c can refuse to load incompatible modules with a clean
* error message. Typical examples that cause incompatibilities are any
* changes to node tags or node structures. (Note that dfmgr.c already
* detects common sources of incompatibilities due to major version
* differences and due to some changed compile-time constants. This setting
* is for catching anything that cannot be detected in a straightforward way.)
*
* There is no prescribed format for the string. The suggestion is to include
* product or company name, and optionally any internally-relevant ABI
* version. Example: "ACME Postgres/1.2". Note that the string will appear
* in a user-facing error message if an ABI mismatch is detected.
*/
#define FMGR_ABI_EXTRA "PostgreSQL"
/*
* Maximum number of columns in an index. There is little point in making
* this anything but a multiple of 32, because the main cost is associated
* with index tuple header size (see access/itup.h).
*
* Changing this requires an initdb.
*/
#define INDEX_MAX_KEYS 32
/*
* Maximum number of columns in a partition key
*/
#define PARTITION_MAX_KEYS 32
/*
* Decide whether built-in 8-byte types, including float8, int8, and
* timestamp, are passed by value. This is on by default if sizeof(Datum) >=
* 8 (that is, on 64-bit platforms). If sizeof(Datum) < 8 (32-bit platforms),
* this must be off. We keep this here as an option so that it is easy to
* test the pass-by-reference code paths on 64-bit platforms.
*
* Changing this requires an initdb.
*/
#if SIZEOF_VOID_P >= 8
#define USE_FLOAT8_BYVAL 1
#endif
/*
* When we don't have native spinlocks, we use semaphores to simulate them.
* Decreasing this value reduces consumption of OS resources; increasing it
* may improve performance, but supplying a real spinlock implementation is
* probably far better.
*/
#define NUM_SPINLOCK_SEMAPHORES 128
/*
* When we have neither spinlocks nor atomic operations support we're
* implementing atomic operations on top of spinlock on top of semaphores. To
* be safe against atomic operations while holding a spinlock separate
* semaphores have to be used.
*/
#define NUM_ATOMICS_SEMAPHORES 64
/*
* MAXPGPATH: standard size of a pathname buffer in PostgreSQL (hence,
* maximum usable pathname length is one less).
*
* We'd use a standard system header symbol for this, if there weren't
* so many to choose from: MAXPATHLEN, MAX_PATH, PATH_MAX are all
* defined by different "standards", and often have different values
* on the same platform! So we just punt and use a reasonably
* generous setting here.
*/
#define MAXPGPATH 1024
/*
* You can try changing this if you have a machine with bytes of
* another size, but no guarantee...
*/
#define BITS_PER_BYTE 8
/*
* Preferred alignment for disk I/O buffers. On some CPUs, copies between
* user space and kernel space are significantly faster if the user buffer
* is aligned on a larger-than-MAXALIGN boundary. Ideally this should be
* a platform-dependent value, but for now we just hard-wire it.
*/
#define ALIGNOF_BUFFER 32
/*
* If EXEC_BACKEND is defined, the postmaster uses an alternative method for
* starting subprocesses: Instead of simply using fork(), as is standard on
* Unix platforms, it uses fork()+exec() or something equivalent on Windows,
* as well as lots of extra code to bring the required global state to those
* new processes. This must be enabled on Windows (because there is no
* fork()). On other platforms, it's only useful for verifying those
* otherwise Windows-specific code paths.
*/
#if defined(WIN32) && !defined(__CYGWIN__)
#define EXEC_BACKEND
#endif
/*
* USE_POSIX_FADVISE controls whether Postgres will attempt to use the
* posix_fadvise() kernel call. Usually the automatic configure tests are
* sufficient, but some older Linux distributions had broken versions of
* posix_fadvise(). If necessary you can remove the #define here.
*/
#if HAVE_DECL_POSIX_FADVISE && defined(HAVE_POSIX_FADVISE)
#define USE_POSIX_FADVISE
#endif
/*
* USE_PREFETCH code should be compiled only if we have a way to implement
* prefetching. (This is decoupled from USE_POSIX_FADVISE because there
* might in future be support for alternative low-level prefetch APIs.
* If you change this, you probably need to adjust the error message in
* check_effective_io_concurrency.)
*/
#ifdef USE_POSIX_FADVISE
#define USE_PREFETCH
#endif
/*
* Default and maximum values for backend_flush_after, bgwriter_flush_after
* and checkpoint_flush_after; measured in blocks. Currently, these are
* enabled by default if sync_file_range() exists, ie, only on Linux. Perhaps
* we could also enable by default if we have mmap and msync(MS_ASYNC)?
*/
#ifdef HAVE_SYNC_FILE_RANGE
#define DEFAULT_BACKEND_FLUSH_AFTER 0 /* never enabled by default */
#define DEFAULT_BGWRITER_FLUSH_AFTER 64
#define DEFAULT_CHECKPOINT_FLUSH_AFTER 32
#else
#define DEFAULT_BACKEND_FLUSH_AFTER 0
#define DEFAULT_BGWRITER_FLUSH_AFTER 0
#define DEFAULT_CHECKPOINT_FLUSH_AFTER 0
#endif
/* upper limit for all three variables */
#define WRITEBACK_MAX_PENDING_FLUSHES 256
/*
* USE_SSL code should be compiled only when compiling with an SSL
* implementation.
*/
#ifdef USE_OPENSSL
#define USE_SSL
#endif
/*
* This is the default directory in which AF_UNIX socket files are
* placed. Caution: changing this risks breaking your existing client
* applications, which are likely to continue to look in the old
* directory. But if you just hate the idea of sockets in /tmp,
* here's where to twiddle it. You can also override this at runtime
* with the postmaster's -k switch.
*
* If set to an empty string, then AF_UNIX sockets are not used by default: A
* server will not create an AF_UNIX socket unless the run-time configuration
* is changed, a client will connect via TCP/IP by default and will only use
* an AF_UNIX socket if one is explicitly specified.
*
* This is done by default on Windows because there is no good standard
* location for AF_UNIX sockets and many installations on Windows don't
* support them yet.
*/
#ifndef WIN32
#define DEFAULT_PGSOCKET_DIR "/tmp"
#else
#define DEFAULT_PGSOCKET_DIR ""
#endif
/*
* This is the default event source for Windows event log.
*/
#define DEFAULT_EVENT_SOURCE "PostgreSQL"
/*
* Assumed cache line size. This doesn't affect correctness, but can be used
* for low-level optimizations. This is mostly used to pad various data
* structures, to ensure that highly-contended fields are on different cache
* lines. Too small a value can hurt performance due to false sharing, while
* the only downside of too large a value is a few bytes of wasted memory.
* The default is 128, which should be large enough for all supported
* platforms.
*/
#define PG_CACHE_LINE_SIZE 128
/*
* Assumed alignment requirement for direct I/O. 4K corresponds to common
* sector and memory page size.
*/
#define PG_IO_ALIGN_SIZE 4096
/*
*------------------------------------------------------------------------
* The following symbols are for enabling debugging code, not for
* controlling user-visible features or resource limits.
*------------------------------------------------------------------------
*/
/*
* Force use of the non-recursive JSON parser in all cases. This is useful
* to validate the working of the parser, and the regression tests should
* pass except for some different error messages about the stack limit.
*/
/* #define FORCE_JSON_PSTACK */
/*
* Include Valgrind "client requests", mostly in the memory allocator, so
* Valgrind understands PostgreSQL memory contexts. This permits detecting
* memory errors that Valgrind would not detect on a vanilla build. It also
* enables detection of buffer accesses that take place without holding a
* buffer pin (or without holding a buffer lock in the case of index access
* methods that superimpose their own custom client requests on top of the
* generic bufmgr.c requests).
*
* "make installcheck" is significantly slower under Valgrind. The client
* requests fall in hot code paths, so USE_VALGRIND slows execution by a few
* percentage points even when not run under Valgrind.
*
* Do not try to test the server under Valgrind without having built the
* server with USE_VALGRIND; else you will get false positives from sinval
* messaging (see comments in AddCatcacheInvalidationMessage). It's also
* important to use the suppression file src/tools/valgrind.supp to
* exclude other known false positives.
*
* You should normally use MEMORY_CONTEXT_CHECKING with USE_VALGRIND;
* instrumentation of repalloc() is inferior without it.
*/
/* #define USE_VALGRIND */
/*
* Define this to cause pfree()'d memory to be cleared immediately, to
* facilitate catching bugs that refer to already-freed values.
* Right now, this gets defined automatically if --enable-cassert.
*/
#ifdef USE_ASSERT_CHECKING
#define CLOBBER_FREED_MEMORY
#endif
/*
* Define this to check memory allocation errors (scribbling on more
* bytes than were allocated). Right now, this gets defined
* automatically if --enable-cassert or USE_VALGRIND.
*/
#if defined(USE_ASSERT_CHECKING) || defined(USE_VALGRIND)
#define MEMORY_CONTEXT_CHECKING
#endif
/*
* Define this to cause palloc()'d memory to be filled with random data, to
* facilitate catching code that depends on the contents of uninitialized
* memory. Caution: this is horrendously expensive.
*/
/* #define RANDOMIZE_ALLOCATED_MEMORY */
/*
* For cache-invalidation debugging, define DISCARD_CACHES_ENABLED to enable
* use of the debug_discard_caches GUC to aggressively flush syscache/relcache
* entries whenever it's possible to deliver invalidations. See
* AcceptInvalidationMessages() in src/backend/utils/cache/inval.c for
* details.
*
* USE_ASSERT_CHECKING builds default to enabling this. It's possible to use
* DISCARD_CACHES_ENABLED without a cassert build and the implied
* CLOBBER_FREED_MEMORY and MEMORY_CONTEXT_CHECKING options, but it's unlikely
* to be as effective at identifying problems.
*/
/* #define DISCARD_CACHES_ENABLED */
#if defined(USE_ASSERT_CHECKING) && !defined(DISCARD_CACHES_ENABLED)
#define DISCARD_CACHES_ENABLED
#endif
/*
* Backwards compatibility for the older compile-time-only clobber-cache
* macros.
*/
#if !defined(DISCARD_CACHES_ENABLED) && (defined(CLOBBER_CACHE_ALWAYS) || defined(CLOBBER_CACHE_RECURSIVELY))
#define DISCARD_CACHES_ENABLED
#endif
/*
* Recover memory used for relcache entries when invalidated. See
* RelationBuildDesc() in src/backend/utils/cache/relcache.c.
*
* This is active automatically for clobber-cache builds when clobbering is
* active, but can be overridden here by explicitly defining
* RECOVER_RELATION_BUILD_MEMORY. Define to 1 to always free relation cache
* memory even when clobber is off, or to 0 to never free relation cache
* memory even when clobbering is on.
*/
/* #define RECOVER_RELATION_BUILD_MEMORY 0 */ /* Force disable */
/* #define RECOVER_RELATION_BUILD_MEMORY 1 */ /* Force enable */
/*
* Define this to force all parse and plan trees to be passed through
* copyObject(), to facilitate catching errors and omissions in
* copyObject().
*/
/* #define COPY_PARSE_PLAN_TREES */
/*
* Define this to force Bitmapset reallocation on each modification. Helps
* to find dangling pointers to Bitmapset's.
*/
/* #define REALLOCATE_BITMAPSETS */
/*
* Define this to force all parse and plan trees to be passed through
* outfuncs.c/readfuncs.c, to facilitate catching errors and omissions in
* those modules.
*/
/* #define WRITE_READ_PARSE_PLAN_TREES */
/*
* Define this to force all raw parse trees for DML statements to be scanned
* by raw_expression_tree_walker(), to facilitate catching errors and
* omissions in that function.
*/
/* #define RAW_EXPRESSION_COVERAGE_TEST */
/*
* Enable debugging print statements for lock-related operations.
*/
/* #define LOCK_DEBUG */
/*
* Enable debugging print statements for WAL-related operations; see
* also the wal_debug GUC var.
*/
/* #define WAL_DEBUG */
/*
* Enable tracing of resource consumption during sort operations;
* see also the trace_sort GUC var. For 8.1 this is enabled by default.
*/
#define TRACE_SORT 1
/*
* Enable tracing of syncscan operations (see also the trace_syncscan GUC var).
*/
/* #define TRACE_SYNCSCAN */
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