1 /*------------------------------------------------------------------------ 2 * PostgreSQL manual configuration settings 3 * 4 * This file contains various configuration symbols and limits. In 5 * all cases, changing them is only useful in very rare situations or 6 * for developers. If you edit any of these, be sure to do a *full* 7 * rebuild (and an initdb if noted). 8 * 9 * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group 10 * Portions Copyright (c) 1994, Regents of the University of California 11 * 12 * src/include/pg_config_manual.h 13 *------------------------------------------------------------------------ 14 */ 15 16 /* 17 * This is the default value for wal_segment_size to be used when initdb is run 18 * without the --wal-segsize option. It must be a valid segment size. 19 */ 20 #define DEFAULT_XLOG_SEG_SIZE (16*1024*1024) 21 22 /* 23 * Maximum length for identifiers (e.g. table names, column names, 24 * function names). Names actually are limited to one less byte than this, 25 * because the length must include a trailing zero byte. 26 * 27 * Changing this requires an initdb. 28 */ 29 #define NAMEDATALEN 64 30 31 /* 32 * Maximum number of arguments to a function. 33 * 34 * The minimum value is 8 (GIN indexes use 8-argument support functions). 35 * The maximum possible value is around 600 (limited by index tuple size in 36 * pg_proc's index; BLCKSZ larger than 8K would allow more). Values larger 37 * than needed will waste memory and processing time, but do not directly 38 * cost disk space. 39 * 40 * Changing this does not require an initdb, but it does require a full 41 * backend recompile (including any user-defined C functions). 42 */ 43 #define FUNC_MAX_ARGS 100 44 45 /* 46 * Maximum number of columns in an index. There is little point in making 47 * this anything but a multiple of 32, because the main cost is associated 48 * with index tuple header size (see access/itup.h). 49 * 50 * Changing this requires an initdb. 51 */ 52 #define INDEX_MAX_KEYS 32 53 54 /* 55 * Maximum number of columns in a partition key 56 */ 57 #define PARTITION_MAX_KEYS 32 58 59 /* 60 * When we don't have native spinlocks, we use semaphores to simulate them. 61 * Decreasing this value reduces consumption of OS resources; increasing it 62 * may improve performance, but supplying a real spinlock implementation is 63 * probably far better. 64 */ 65 #define NUM_SPINLOCK_SEMAPHORES 128 66 67 /* 68 * When we have neither spinlocks nor atomic operations support we're 69 * implementing atomic operations on top of spinlock on top of semaphores. To 70 * be safe against atomic operations while holding a spinlock separate 71 * semaphores have to be used. 72 */ 73 #define NUM_ATOMICS_SEMAPHORES 64 74 75 /* 76 * MAXPGPATH: standard size of a pathname buffer in PostgreSQL (hence, 77 * maximum usable pathname length is one less). 78 * 79 * We'd use a standard system header symbol for this, if there weren't 80 * so many to choose from: MAXPATHLEN, MAX_PATH, PATH_MAX are all 81 * defined by different "standards", and often have different values 82 * on the same platform! So we just punt and use a reasonably 83 * generous setting here. 84 */ 85 #define MAXPGPATH 1024 86 87 /* 88 * PG_SOMAXCONN: maximum accept-queue length limit passed to 89 * listen(2). You'd think we should use SOMAXCONN from 90 * <sys/socket.h>, but on many systems that symbol is much smaller 91 * than the kernel's actual limit. In any case, this symbol need be 92 * twiddled only if you have a kernel that refuses large limit values, 93 * rather than silently reducing the value to what it can handle 94 * (which is what most if not all Unixen do). 95 */ 96 #define PG_SOMAXCONN 10000 97 98 /* 99 * You can try changing this if you have a machine with bytes of 100 * another size, but no guarantee... 101 */ 102 #define BITS_PER_BYTE 8 103 104 /* 105 * Preferred alignment for disk I/O buffers. On some CPUs, copies between 106 * user space and kernel space are significantly faster if the user buffer 107 * is aligned on a larger-than-MAXALIGN boundary. Ideally this should be 108 * a platform-dependent value, but for now we just hard-wire it. 109 */ 110 #define ALIGNOF_BUFFER 32 111 112 /* 113 * Disable UNIX sockets for certain operating systems. 114 */ 115 #if defined(WIN32) 116 #undef HAVE_UNIX_SOCKETS 117 #endif 118 119 /* 120 * Define this if your operating system supports link() 121 */ 122 #if !defined(WIN32) && !defined(__CYGWIN__) 123 #define HAVE_WORKING_LINK 1 124 #endif 125 126 /* 127 * USE_POSIX_FADVISE controls whether Postgres will attempt to use the 128 * posix_fadvise() kernel call. Usually the automatic configure tests are 129 * sufficient, but some older Linux distributions had broken versions of 130 * posix_fadvise(). If necessary you can remove the #define here. 131 */ 132 #if HAVE_DECL_POSIX_FADVISE && defined(HAVE_POSIX_FADVISE) 133 #define USE_POSIX_FADVISE 134 #endif 135 136 /* 137 * USE_PREFETCH code should be compiled only if we have a way to implement 138 * prefetching. (This is decoupled from USE_POSIX_FADVISE because there 139 * might in future be support for alternative low-level prefetch APIs. 140 * If you change this, you probably need to adjust the error message in 141 * check_effective_io_concurrency.) 142 */ 143 #ifdef USE_POSIX_FADVISE 144 #define USE_PREFETCH 145 #endif 146 147 /* 148 * Default and maximum values for backend_flush_after, bgwriter_flush_after 149 * and checkpoint_flush_after; measured in blocks. Currently, these are 150 * enabled by default if sync_file_range() exists, ie, only on Linux. Perhaps 151 * we could also enable by default if we have mmap and msync(MS_ASYNC)? 152 */ 153 #ifdef HAVE_SYNC_FILE_RANGE 154 #define DEFAULT_BACKEND_FLUSH_AFTER 0 /* never enabled by default */ 155 #define DEFAULT_BGWRITER_FLUSH_AFTER 64 156 #define DEFAULT_CHECKPOINT_FLUSH_AFTER 32 157 #else 158 #define DEFAULT_BACKEND_FLUSH_AFTER 0 159 #define DEFAULT_BGWRITER_FLUSH_AFTER 0 160 #define DEFAULT_CHECKPOINT_FLUSH_AFTER 0 161 #endif 162 /* upper limit for all three variables */ 163 #define WRITEBACK_MAX_PENDING_FLUSHES 256 164 165 /* 166 * USE_SSL code should be compiled only when compiling with an SSL 167 * implementation. (Currently, only OpenSSL is supported, but we might add 168 * more implementations in the future.) 169 */ 170 #ifdef USE_OPENSSL 171 #define USE_SSL 172 #endif 173 174 /* 175 * This is the default directory in which AF_UNIX socket files are 176 * placed. Caution: changing this risks breaking your existing client 177 * applications, which are likely to continue to look in the old 178 * directory. But if you just hate the idea of sockets in /tmp, 179 * here's where to twiddle it. You can also override this at runtime 180 * with the postmaster's -k switch. 181 */ 182 #define DEFAULT_PGSOCKET_DIR "/tmp" 183 184 /* 185 * This is the default event source for Windows event log. 186 */ 187 #define DEFAULT_EVENT_SOURCE "PostgreSQL" 188 189 /* 190 * The random() function is expected to yield values between 0 and 191 * MAX_RANDOM_VALUE. Currently, all known implementations yield 192 * 0..2^31-1, so we just hardwire this constant. We could do a 193 * configure test if it proves to be necessary. CAUTION: Think not to 194 * replace this with RAND_MAX. RAND_MAX defines the maximum value of 195 * the older rand() function, which is often different from --- and 196 * considerably inferior to --- random(). 197 */ 198 #define MAX_RANDOM_VALUE PG_INT32_MAX 199 200 /* 201 * On PPC machines, decide whether to use the mutex hint bit in LWARX 202 * instructions. Setting the hint bit will slightly improve spinlock 203 * performance on POWER6 and later machines, but does nothing before that, 204 * and will result in illegal-instruction failures on some pre-POWER4 205 * machines. By default we use the hint bit when building for 64-bit PPC, 206 * which should be safe in nearly all cases. You might want to override 207 * this if you are building 32-bit code for a known-recent PPC machine. 208 */ 209 #ifdef HAVE_PPC_LWARX_MUTEX_HINT /* must have assembler support in any case */ 210 #if defined(__ppc64__) || defined(__powerpc64__) 211 #define USE_PPC_LWARX_MUTEX_HINT 212 #endif 213 #endif 214 215 /* 216 * On PPC machines, decide whether to use LWSYNC instructions in place of 217 * ISYNC and SYNC. This provides slightly better performance, but will 218 * result in illegal-instruction failures on some pre-POWER4 machines. 219 * By default we use LWSYNC when building for 64-bit PPC, which should be 220 * safe in nearly all cases. 221 */ 222 #if defined(__ppc64__) || defined(__powerpc64__) 223 #define USE_PPC_LWSYNC 224 #endif 225 226 /* 227 * Assumed cache line size. This doesn't affect correctness, but can be used 228 * for low-level optimizations. Currently, this is used to pad some data 229 * structures in xlog.c, to ensure that highly-contended fields are on 230 * different cache lines. Too small a value can hurt performance due to false 231 * sharing, while the only downside of too large a value is a few bytes of 232 * wasted memory. The default is 128, which should be large enough for all 233 * supported platforms. 234 */ 235 #define PG_CACHE_LINE_SIZE 128 236 237 /* 238 *------------------------------------------------------------------------ 239 * The following symbols are for enabling debugging code, not for 240 * controlling user-visible features or resource limits. 241 *------------------------------------------------------------------------ 242 */ 243 244 /* 245 * Include Valgrind "client requests", mostly in the memory allocator, so 246 * Valgrind understands PostgreSQL memory contexts. This permits detecting 247 * memory errors that Valgrind would not detect on a vanilla build. See also 248 * src/tools/valgrind.supp. "make installcheck" runs 20-30x longer under 249 * Valgrind. Note that USE_VALGRIND slowed older versions of Valgrind by an 250 * additional order of magnitude; Valgrind 3.8.1 does not have this problem. 251 * The client requests fall in hot code paths, so USE_VALGRIND also slows 252 * native execution by a few percentage points. 253 * 254 * You should normally use MEMORY_CONTEXT_CHECKING with USE_VALGRIND; 255 * instrumentation of repalloc() is inferior without it. 256 */ 257 /* #define USE_VALGRIND */ 258 259 /* 260 * Define this to cause pfree()'d memory to be cleared immediately, to 261 * facilitate catching bugs that refer to already-freed values. 262 * Right now, this gets defined automatically if --enable-cassert. 263 */ 264 #ifdef USE_ASSERT_CHECKING 265 #define CLOBBER_FREED_MEMORY 266 #endif 267 268 /* 269 * Define this to check memory allocation errors (scribbling on more 270 * bytes than were allocated). Right now, this gets defined 271 * automatically if --enable-cassert or USE_VALGRIND. 272 */ 273 #if defined(USE_ASSERT_CHECKING) || defined(USE_VALGRIND) 274 #define MEMORY_CONTEXT_CHECKING 275 #endif 276 277 /* 278 * Define this to cause palloc()'d memory to be filled with random data, to 279 * facilitate catching code that depends on the contents of uninitialized 280 * memory. Caution: this is horrendously expensive. 281 */ 282 /* #define RANDOMIZE_ALLOCATED_MEMORY */ 283 284 /* 285 * Define this to force all parse and plan trees to be passed through 286 * copyObject(), to facilitate catching errors and omissions in 287 * copyObject(). 288 */ 289 /* #define COPY_PARSE_PLAN_TREES */ 290 291 /* 292 * Define this to force all parse and plan trees to be passed through 293 * outfuncs.c/readfuncs.c, to facilitate catching errors and omissions in 294 * those modules. 295 */ 296 /* #define WRITE_READ_PARSE_PLAN_TREES */ 297 298 /* 299 * Define this to force all raw parse trees for DML statements to be scanned 300 * by raw_expression_tree_walker(), to facilitate catching errors and 301 * omissions in that function. 302 */ 303 /* #define RAW_EXPRESSION_COVERAGE_TEST */ 304 305 /* 306 * Enable debugging print statements for lock-related operations. 307 */ 308 /* #define LOCK_DEBUG */ 309 310 /* 311 * Enable debugging print statements for WAL-related operations; see 312 * also the wal_debug GUC var. 313 */ 314 /* #define WAL_DEBUG */ 315 316 /* 317 * Enable tracing of resource consumption during sort operations; 318 * see also the trace_sort GUC var. For 8.1 this is enabled by default. 319 */ 320 #define TRACE_SORT 1 321 322 /* 323 * Enable tracing of syncscan operations (see also the trace_syncscan GUC var). 324 */ 325 /* #define TRACE_SYNCSCAN */ 326 327 /* 328 * Other debug #defines (documentation, anyone?) 329 */ 330 /* #define HEAPDEBUGALL */ 331 /* #define ACLDEBUG */ 332