1 /* 2 ** 2007 May 7 3 ** 4 ** The author disclaims copyright to this source code. In place of 5 ** a legal notice, here is a blessing: 6 ** 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. 10 ** 11 ************************************************************************* 12 ** 13 ** This file defines various limits of what SQLite can process. 14 */ 15 16 /* 17 ** The maximum length of a TEXT or BLOB in bytes. This also 18 ** limits the size of a row in a table or index. 19 ** 20 ** The hard limit is the ability of a 32-bit signed integer 21 ** to count the size: 2^31-1 or 2147483647. 22 */ 23 #ifndef SQLITE_MAX_LENGTH 24 # define SQLITE_MAX_LENGTH 1000000000 25 #endif 26 27 /* 28 ** This is the maximum number of 29 ** 30 ** * Columns in a table 31 ** * Columns in an index 32 ** * Columns in a view 33 ** * Terms in the SET clause of an UPDATE statement 34 ** * Terms in the result set of a SELECT statement 35 ** * Terms in the GROUP BY or ORDER BY clauses of a SELECT statement. 36 ** * Terms in the VALUES clause of an INSERT statement 37 ** 38 ** The hard upper limit here is 32676. Most database people will 39 ** tell you that in a well-normalized database, you usually should 40 ** not have more than a dozen or so columns in any table. And if 41 ** that is the case, there is no point in having more than a few 42 ** dozen values in any of the other situations described above. 43 */ 44 #ifndef SQLITE_MAX_COLUMN 45 # define SQLITE_MAX_COLUMN 2000 46 #endif 47 48 /* 49 ** The maximum length of a single SQL statement in bytes. 50 ** 51 ** It used to be the case that setting this value to zero would 52 ** turn the limit off. That is no longer true. It is not possible 53 ** to turn this limit off. 54 */ 55 #ifndef SQLITE_MAX_SQL_LENGTH 56 # define SQLITE_MAX_SQL_LENGTH 1000000000 57 #endif 58 59 /* 60 ** The maximum depth of an expression tree. This is limited to 61 ** some extent by SQLITE_MAX_SQL_LENGTH. But sometime you might 62 ** want to place more severe limits on the complexity of an 63 ** expression. 64 ** 65 ** A value of 0 used to mean that the limit was not enforced. 66 ** But that is no longer true. The limit is now strictly enforced 67 ** at all times. 68 */ 69 #ifndef SQLITE_MAX_EXPR_DEPTH 70 # define SQLITE_MAX_EXPR_DEPTH 1000 71 #endif 72 73 /* 74 ** The maximum number of terms in a compound SELECT statement. 75 ** The code generator for compound SELECT statements does one 76 ** level of recursion for each term. A stack overflow can result 77 ** if the number of terms is too large. In practice, most SQL 78 ** never has more than 3 or 4 terms. Use a value of 0 to disable 79 ** any limit on the number of terms in a compount SELECT. 80 */ 81 #ifndef SQLITE_MAX_COMPOUND_SELECT 82 # define SQLITE_MAX_COMPOUND_SELECT 500 83 #endif 84 85 /* 86 ** The maximum number of opcodes in a VDBE program. 87 ** Not currently enforced. 88 */ 89 #ifndef SQLITE_MAX_VDBE_OP 90 # define SQLITE_MAX_VDBE_OP 25000 91 #endif 92 93 /* 94 ** The maximum number of arguments to an SQL function. 95 */ 96 #ifndef SQLITE_MAX_FUNCTION_ARG 97 # define SQLITE_MAX_FUNCTION_ARG 127 98 #endif 99 100 /* 101 ** The maximum number of in-memory pages to use for the main database 102 ** table and for temporary tables. The SQLITE_DEFAULT_CACHE_SIZE 103 */ 104 #ifndef SQLITE_DEFAULT_CACHE_SIZE 105 # define SQLITE_DEFAULT_CACHE_SIZE 2000 106 #endif 107 #ifndef SQLITE_DEFAULT_TEMP_CACHE_SIZE 108 # define SQLITE_DEFAULT_TEMP_CACHE_SIZE 500 109 #endif 110 111 /* 112 ** The maximum number of attached databases. This must be between 0 113 ** and 30. The upper bound on 30 is because a 32-bit integer bitmap 114 ** is used internally to track attached databases. 115 */ 116 #ifndef SQLITE_MAX_ATTACHED 117 # define SQLITE_MAX_ATTACHED 10 118 #endif 119 120 121 /* 122 ** The maximum value of a ?nnn wildcard that the parser will accept. 123 */ 124 #ifndef SQLITE_MAX_VARIABLE_NUMBER 125 # define SQLITE_MAX_VARIABLE_NUMBER 999 126 #endif 127 128 /* Maximum page size. The upper bound on this value is 32768. This a limit 129 ** imposed by the necessity of storing the value in a 2-byte unsigned integer 130 ** and the fact that the page size must be a power of 2. 131 ** 132 ** If this limit is changed, then the compiled library is technically 133 ** incompatible with an SQLite library compiled with a different limit. If 134 ** a process operating on a database with a page-size of 65536 bytes 135 ** crashes, then an instance of SQLite compiled with the default page-size 136 ** limit will not be able to rollback the aborted transaction. This could 137 ** lead to database corruption. 138 */ 139 #ifndef SQLITE_MAX_PAGE_SIZE 140 # define SQLITE_MAX_PAGE_SIZE 32768 141 #endif 142 143 144 /* 145 ** The default size of a database page. 146 */ 147 #ifndef SQLITE_DEFAULT_PAGE_SIZE 148 # define SQLITE_DEFAULT_PAGE_SIZE 1024 149 #endif 150 #if SQLITE_DEFAULT_PAGE_SIZE>SQLITE_MAX_PAGE_SIZE 151 # undef SQLITE_DEFAULT_PAGE_SIZE 152 # define SQLITE_DEFAULT_PAGE_SIZE SQLITE_MAX_PAGE_SIZE 153 #endif 154 155 /* 156 ** Ordinarily, if no value is explicitly provided, SQLite creates databases 157 ** with page size SQLITE_DEFAULT_PAGE_SIZE. However, based on certain 158 ** device characteristics (sector-size and atomic write() support), 159 ** SQLite may choose a larger value. This constant is the maximum value 160 ** SQLite will choose on its own. 161 */ 162 #ifndef SQLITE_MAX_DEFAULT_PAGE_SIZE 163 # define SQLITE_MAX_DEFAULT_PAGE_SIZE 8192 164 #endif 165 #if SQLITE_MAX_DEFAULT_PAGE_SIZE>SQLITE_MAX_PAGE_SIZE 166 # undef SQLITE_MAX_DEFAULT_PAGE_SIZE 167 # define SQLITE_MAX_DEFAULT_PAGE_SIZE SQLITE_MAX_PAGE_SIZE 168 #endif 169 170 171 /* 172 ** Maximum number of pages in one database file. 173 ** 174 ** This is really just the default value for the max_page_count pragma. 175 ** This value can be lowered (or raised) at run-time using that the 176 ** max_page_count macro. 177 */ 178 #ifndef SQLITE_MAX_PAGE_COUNT 179 # define SQLITE_MAX_PAGE_COUNT 1073741823 180 #endif 181 182 /* 183 ** Maximum length (in bytes) of the pattern in a LIKE or GLOB 184 ** operator. 185 */ 186 #ifndef SQLITE_MAX_LIKE_PATTERN_LENGTH 187 # define SQLITE_MAX_LIKE_PATTERN_LENGTH 50000 188 #endif 189 190 /* 191 ** Maximum depth of recursion for triggers. 192 ** 193 ** A value of 1 means that a trigger program will not be able to itself 194 ** fire any triggers. A value of 0 means that no trigger programs at all 195 ** may be executed. 196 */ 197 #ifndef SQLITE_MAX_TRIGGER_DEPTH 198 # define SQLITE_MAX_TRIGGER_DEPTH 1000 199 #endif 200