1 /*------------------------------------------------------------------------
2 * PostgreSQL manual configuration settings
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).
9 * $PostgreSQL: pgsql/src/include/pg_config_manual.h,v 1.28 2008/02/29 20:58:33 alvherre Exp $
10 *------------------------------------------------------------------------
14 * Size of a disk block --- this also limits the size of a tuple. You
15 * can set it bigger if you need bigger tuples (although TOAST should
16 * reduce the need to have large tuples, since fields can be spread
17 * across multiple tuples).
19 * BLCKSZ must be a power of 2. The maximum possible value of BLCKSZ
20 * is currently 2^15 (32768). This is determined by the 15-bit widths
21 * of the lp_off and lp_len fields in ItemIdData (see
22 * include/storage/itemid.h).
24 * Changing BLCKSZ requires an initdb.
29 * RELSEG_SIZE is the maximum number of blocks allowed in one disk
30 * file. Thus, the maximum size of a single file is RELSEG_SIZE *
31 * BLCKSZ; relations bigger than that are divided into multiple files.
33 * RELSEG_SIZE * BLCKSZ must be less than your OS' limit on file size.
34 * This is often 2 GB or 4GB in a 32-bit operating system, unless you
35 * have large file support enabled. By default, we make the limit 1
36 * GB to avoid any possible integer-overflow problems within the OS.
37 * A limit smaller than necessary only means we divide a large
38 * relation into more chunks than necessary, so it seems best to err
39 * in the direction of a small limit. (Besides, a power-of-2 value
40 * saves a few cycles in md.c.)
42 * Changing RELSEG_SIZE requires an initdb.
44 #define RELSEG_SIZE (0x40000000 / BLCKSZ)
47 * Size of a WAL file block. This need have no particular relation to BLCKSZ.
48 * XLOG_BLCKSZ must be a power of 2, and if your system supports O_DIRECT I/O,
49 * XLOG_BLCKSZ must be a multiple of the alignment requirement for direct-I/O
50 * buffers, else direct I/O may fail.
52 * Changing XLOG_BLCKSZ requires an initdb.
54 #define XLOG_BLCKSZ 8192
57 * XLOG_SEG_SIZE is the size of a single WAL file. This must be a power of 2
58 * and larger than XLOG_BLCKSZ (preferably, a great deal larger than
61 * Changing XLOG_SEG_SIZE requires an initdb.
63 #define XLOG_SEG_SIZE (16*1024*1024)
66 * Maximum length for identifiers (e.g. table names, column names,
67 * function names). It must be a multiple of sizeof(int) (typically
70 * Changing this requires an initdb.
72 #define NAMEDATALEN 64
75 * Maximum number of arguments to a function.
77 * The minimum value is 8 (index cost estimation uses 8-argument functions).
78 * The maximum possible value is around 600 (limited by index tuple size in
79 * pg_proc's index; BLCKSZ larger than 8K would allow more). Values larger
80 * than needed will waste memory and processing time, but do not directly
83 * Changing this does not require an initdb, but it does require a full
84 * backend recompile (including any user-defined C functions).
86 #define FUNC_MAX_ARGS 100
89 * Maximum number of columns in an index. There is little point in making
90 * this anything but a multiple of 32, because the main cost is associated
91 * with index tuple header size (see access/itup.h).
93 * Changing this requires an initdb.
95 #define INDEX_MAX_KEYS 32
98 * Number of spare LWLocks to allocate for user-defined add-on code.
100 #define NUM_USER_DEFINED_LWLOCKS 4
103 * Define this if you want psql to _always_ ask for a username and a
104 * password for password authentication.
106 /* #define PSQL_ALWAYS_GET_PASSWORDS */
109 * Define this if you want to allow the lo_import and lo_export SQL
110 * functions to be executed by ordinary users. By default these
111 * functions are only available to the Postgres superuser. CAUTION:
112 * These functions are SECURITY HOLES since they can read and write
113 * any file that the PostgreSQL server has permission to access. If
114 * you turn this on, don't say we didn't warn you.
116 /* #define ALLOW_DANGEROUS_LO_FUNCTIONS */
119 * MAXPGPATH: standard size of a pathname buffer in PostgreSQL (hence,
120 * maximum usable pathname length is one less).
122 * We'd use a standard system header symbol for this, if there weren't
123 * so many to choose from: MAXPATHLEN, MAX_PATH, PATH_MAX are all
124 * defined by different "standards", and often have different values
125 * on the same platform! So we just punt and use a reasonably
126 * generous setting here.
128 #define MAXPGPATH 1024
131 * PG_SOMAXCONN: maximum accept-queue length limit passed to
132 * listen(2). You'd think we should use SOMAXCONN from
133 * <sys/socket.h>, but on many systems that symbol is much smaller
134 * than the kernel's actual limit. In any case, this symbol need be
135 * twiddled only if you have a kernel that refuses large limit values,
136 * rather than silently reducing the value to what it can handle
137 * (which is what most if not all Unixen do).
139 #define PG_SOMAXCONN 10000
142 * You can try changing this if you have a machine with bytes of
143 * another size, but no guarantee...
145 #define BITS_PER_BYTE 8
148 * Preferred alignment for disk I/O buffers. On some CPUs, copies between
149 * user space and kernel space are significantly faster if the user buffer
150 * is aligned on a larger-than-MAXALIGN boundary. Ideally this should be
151 * a platform-dependent value, but for now we just hard-wire it.
153 #define ALIGNOF_BUFFER 32
156 * Disable UNIX sockets for those operating system.
159 #undef HAVE_UNIX_SOCKETS
163 * Define this if your operating system supports link()
165 #if !defined(WIN32) && !defined(__CYGWIN__)
166 #define HAVE_WORKING_LINK 1
170 * This is the default directory in which AF_UNIX socket files are
171 * placed. Caution: changing this risks breaking your existing client
172 * applications, which are likely to continue to look in the old
173 * directory. But if you just hate the idea of sockets in /tmp,
174 * here's where to twiddle it. You can also override this at runtime
175 * with the postmaster's -k switch.
177 #define DEFAULT_PGSOCKET_DIR "/tmp"
180 * The random() function is expected to yield values between 0 and
181 * MAX_RANDOM_VALUE. Currently, all known implementations yield
182 * 0..2^31-1, so we just hardwire this constant. We could do a
183 * configure test if it proves to be necessary. CAUTION: Think not to
184 * replace this with RAND_MAX. RAND_MAX defines the maximum value of
185 * the older rand() function, which is often different from --- and
186 * considerably inferior to --- random().
188 #define MAX_RANDOM_VALUE (0x7FFFFFFF)
192 *------------------------------------------------------------------------
193 * The following symbols are for enabling debugging code, not for
194 * controlling user-visible features or resource limits.
195 *------------------------------------------------------------------------
199 * Define this to cause pfree()'d memory to be cleared immediately, to
200 * facilitate catching bugs that refer to already-freed values. XXX
201 * Right now, this gets defined automatically if --enable-cassert. In
202 * the long term it probably doesn't need to be on by default.
204 #ifdef USE_ASSERT_CHECKING
205 #define CLOBBER_FREED_MEMORY
209 * Define this to check memory allocation errors (scribbling on more
210 * bytes than were allocated). Right now, this gets defined
211 * automatically if --enable-cassert. In the long term it probably
212 * doesn't need to be on by default.
214 #ifdef USE_ASSERT_CHECKING
215 #define MEMORY_CONTEXT_CHECKING
219 * Define this to force all parse and plan trees to be passed through
220 * copyObject(), to facilitate catching errors and omissions in
223 /* #define COPY_PARSE_PLAN_TREES */
226 * Enable debugging print statements for lock-related operations.
228 /* #define LOCK_DEBUG */
231 * Enable debugging print statements for WAL-related operations; see
232 * also the wal_debug GUC var.
234 /* #define WAL_DEBUG */
237 * Enable tracing of resource consumption during sort operations;
238 * see also the trace_sort GUC var. For 8.1 this is enabled by default.
243 * Enable tracing of syncscan operations (see also the trace_syncscan GUC var).
245 /* #define TRACE_SYNCSCAN */
248 * Other debug #defines (documentation, anyone?)
250 /* #define HEAPDEBUGALL */
251 /* #define ACLDEBUG */
252 /* #define RTDEBUG */