4 ** The author disclaims copyright to this source code. In place of
5 ** a legal notice, here is a blessing:
7 ** May you do good and not evil.
8 ** May you find forgiveness for yourself and forgive others.
9 ** May you share freely, never taking more than you give.
11 *************************************************************************
13 ** This file defines various limits of what SQLite can process.
15 ** @(#) $Id: sqliteLimit.h,v 1.8 2008/03/26 15:56:22 drh Exp $
19 ** The maximum length of a TEXT or BLOB in bytes. This also
20 ** limits the size of a row in a table or index.
22 ** The hard limit is the ability of a 32-bit signed integer
23 ** to count the size: 2^31-1 or 2147483647.
25 #ifndef SQLITE_MAX_LENGTH
26 # define SQLITE_MAX_LENGTH 1000000000
30 ** This is the maximum number of
32 ** * Columns in a table
33 ** * Columns in an index
34 ** * Columns in a view
35 ** * Terms in the SET clause of an UPDATE statement
36 ** * Terms in the result set of a SELECT statement
37 ** * Terms in the GROUP BY or ORDER BY clauses of a SELECT statement.
38 ** * Terms in the VALUES clause of an INSERT statement
40 ** The hard upper limit here is 32676. Most database people will
41 ** tell you that in a well-normalized database, you usually should
42 ** not have more than a dozen or so columns in any table. And if
43 ** that is the case, there is no point in having more than a few
44 ** dozen values in any of the other situations described above.
46 #ifndef SQLITE_MAX_COLUMN
47 # define SQLITE_MAX_COLUMN 2000
51 ** The maximum length of a single SQL statement in bytes.
53 ** It used to be the case that setting this value to zero would
54 ** turn the limit off. That is no longer true. It is not possible
55 ** to turn this limit off.
57 #ifndef SQLITE_MAX_SQL_LENGTH
58 # define SQLITE_MAX_SQL_LENGTH 1000000000
62 ** The maximum depth of an expression tree. This is limited to
63 ** some extent by SQLITE_MAX_SQL_LENGTH. But sometime you might
64 ** want to place more severe limits on the complexity of an
67 ** A value of 0 used to mean that the limit was not enforced.
68 ** But that is no longer true. The limit is now strictly enforced
71 #ifndef SQLITE_MAX_EXPR_DEPTH
72 # define SQLITE_MAX_EXPR_DEPTH 1000
76 ** The maximum number of terms in a compound SELECT statement.
77 ** The code generator for compound SELECT statements does one
78 ** level of recursion for each term. A stack overflow can result
79 ** if the number of terms is too large. In practice, most SQL
80 ** never has more than 3 or 4 terms. Use a value of 0 to disable
81 ** any limit on the number of terms in a compount SELECT.
83 #ifndef SQLITE_MAX_COMPOUND_SELECT
84 # define SQLITE_MAX_COMPOUND_SELECT 500
88 ** The maximum number of opcodes in a VDBE program.
89 ** Not currently enforced.
91 #ifndef SQLITE_MAX_VDBE_OP
92 # define SQLITE_MAX_VDBE_OP 25000
96 ** The maximum number of arguments to an SQL function.
98 #ifndef SQLITE_MAX_FUNCTION_ARG
99 # define SQLITE_MAX_FUNCTION_ARG 100
103 ** The maximum number of in-memory pages to use for the main database
104 ** table and for temporary tables. The SQLITE_DEFAULT_CACHE_SIZE
106 #ifndef SQLITE_DEFAULT_CACHE_SIZE
107 # define SQLITE_DEFAULT_CACHE_SIZE 2000
109 #ifndef SQLITE_DEFAULT_TEMP_CACHE_SIZE
110 # define SQLITE_DEFAULT_TEMP_CACHE_SIZE 500
114 ** The maximum number of attached databases. This must be between 0
115 ** and 30. The upper bound on 30 is because a 32-bit integer bitmap
116 ** is used internally to track attached databases.
118 #ifndef SQLITE_MAX_ATTACHED
119 # define SQLITE_MAX_ATTACHED 10
124 ** The maximum value of a ?nnn wildcard that the parser will accept.
126 #ifndef SQLITE_MAX_VARIABLE_NUMBER
127 # define SQLITE_MAX_VARIABLE_NUMBER 999
130 /* Maximum page size. The upper bound on this value is 32768. This a limit
131 ** imposed by the necessity of storing the value in a 2-byte unsigned integer
132 ** and the fact that the page size must be a power of 2.
134 #ifndef SQLITE_MAX_PAGE_SIZE
135 # define SQLITE_MAX_PAGE_SIZE 32768
140 ** The default size of a database page.
142 #ifndef SQLITE_DEFAULT_PAGE_SIZE
143 # define SQLITE_DEFAULT_PAGE_SIZE 1024
145 #if SQLITE_DEFAULT_PAGE_SIZE>SQLITE_MAX_PAGE_SIZE
146 # undef SQLITE_DEFAULT_PAGE_SIZE
147 # define SQLITE_DEFAULT_PAGE_SIZE SQLITE_MAX_PAGE_SIZE
151 ** Ordinarily, if no value is explicitly provided, SQLite creates databases
152 ** with page size SQLITE_DEFAULT_PAGE_SIZE. However, based on certain
153 ** device characteristics (sector-size and atomic write() support),
154 ** SQLite may choose a larger value. This constant is the maximum value
155 ** SQLite will choose on its own.
157 #ifndef SQLITE_MAX_DEFAULT_PAGE_SIZE
158 # define SQLITE_MAX_DEFAULT_PAGE_SIZE 8192
160 #if SQLITE_MAX_DEFAULT_PAGE_SIZE>SQLITE_MAX_PAGE_SIZE
161 # undef SQLITE_MAX_DEFAULT_PAGE_SIZE
162 # define SQLITE_MAX_DEFAULT_PAGE_SIZE SQLITE_MAX_PAGE_SIZE
167 ** Maximum number of pages in one database file.
169 ** This is really just the default value for the max_page_count pragma.
170 ** This value can be lowered (or raised) at run-time using that the
171 ** max_page_count macro.
173 #ifndef SQLITE_MAX_PAGE_COUNT
174 # define SQLITE_MAX_PAGE_COUNT 1073741823
178 ** Maximum length (in bytes) of the pattern in a LIKE or GLOB
181 #ifndef SQLITE_MAX_LIKE_PATTERN_LENGTH
182 # define SQLITE_MAX_LIKE_PATTERN_LENGTH 50000