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Diffstat (limited to 'src/include/pg_config_manual.h')
-rw-r--r-- | src/include/pg_config_manual.h | 404 |
1 files changed, 404 insertions, 0 deletions
diff --git a/src/include/pg_config_manual.h b/src/include/pg_config_manual.h new file mode 100644 index 0000000..614035e --- /dev/null +++ b/src/include/pg_config_manual.h @@ -0,0 +1,404 @@ +/*------------------------------------------------------------------------ + * 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) 1996-2021, 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 + +/* + * 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 + +/* + * PG_SOMAXCONN: maximum accept-queue length limit passed to + * listen(2). You'd think we should use SOMAXCONN from + * <sys/socket.h>, but on many systems that symbol is much smaller + * than the kernel's actual limit. In any case, this symbol need be + * twiddled only if you have a kernel that refuses large limit values, + * rather than silently reducing the value to what it can handle + * (which is what most if not all Unixen do). + */ +#define PG_SOMAXCONN 10000 + +/* + * 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 + +/* + * Define this if your operating system supports link() + */ +#if !defined(WIN32) && !defined(__CYGWIN__) +#define HAVE_WORKING_LINK 1 +#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" + +/* + * The random() function is expected to yield values between 0 and + * MAX_RANDOM_VALUE. Currently, all known implementations yield + * 0..2^31-1, so we just hardwire this constant. We could do a + * configure test if it proves to be necessary. CAUTION: Think not to + * replace this with RAND_MAX. RAND_MAX defines the maximum value of + * the older rand() function, which is often different from --- and + * considerably inferior to --- random(). + */ +#define MAX_RANDOM_VALUE PG_INT32_MAX + +/* + * On PPC machines, decide whether to use the mutex hint bit in LWARX + * instructions. Setting the hint bit will slightly improve spinlock + * performance on POWER6 and later machines, but does nothing before that, + * and will result in illegal-instruction failures on some pre-POWER4 + * machines. By default we use the hint bit when building for 64-bit PPC, + * which should be safe in nearly all cases. You might want to override + * this if you are building 32-bit code for a known-recent PPC machine. + */ +#ifdef HAVE_PPC_LWARX_MUTEX_HINT /* must have assembler support in any case */ +#if defined(__ppc64__) || defined(__powerpc64__) +#define USE_PPC_LWARX_MUTEX_HINT +#endif +#endif + +/* + * On PPC machines, decide whether to use LWSYNC instructions in place of + * ISYNC and SYNC. This provides slightly better performance, but will + * result in illegal-instruction failures on some pre-POWER4 machines. + * By default we use LWSYNC when building for 64-bit PPC, which should be + * safe in nearly all cases. + */ +#if defined(__ppc64__) || defined(__powerpc64__) +#define USE_PPC_LWSYNC +#endif + +/* + * Assumed cache line size. This doesn't affect correctness, but can be used + * for low-level optimizations. Currently, this is used to pad some data + * structures in xlog.c, 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 + +/* + *------------------------------------------------------------------------ + * The following symbols are for enabling debugging code, not for + * controlling user-visible features or resource limits. + *------------------------------------------------------------------------ + */ + +/* + * 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 + * RelationBuildDescr() 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 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 */ |