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 250000000 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 suggested maximum number of in-memory pages to use for 102 ** the main database table and for temporary tables. 103 ** 104 ** IMPLEMENTATION-OF: R-30185-15359 The default suggested cache size is -2000, 105 ** which means the cache size is limited to 2048000 bytes of memory. 106 ** IMPLEMENTATION-OF: R-48205-43578 The default suggested cache size can be 107 ** altered using the SQLITE_DEFAULT_CACHE_SIZE compile-time options. 108 */ 109 #ifndef SQLITE_DEFAULT_CACHE_SIZE 110 # define SQLITE_DEFAULT_CACHE_SIZE -2000 111 #endif 112 113 /* 114 ** The default number of frames to accumulate in the log file before 115 ** checkpointing the database in WAL mode. 116 */ 117 #ifndef SQLITE_DEFAULT_WAL_AUTOCHECKPOINT 118 # define SQLITE_DEFAULT_WAL_AUTOCHECKPOINT 1000 119 #endif 120 121 /* 122 ** The maximum number of attached databases. This must be between 0 123 ** and 125. The upper bound of 125 is because the attached databases are 124 ** counted using a signed 8-bit integer which has a maximum value of 127 125 ** and we have to allow 2 extra counts for the "main" and "temp" databases. 126 */ 127 #ifndef SQLITE_MAX_ATTACHED 128 # define SQLITE_MAX_ATTACHED 10 129 #endif 130 131 132 /* 133 ** The maximum value of a ?nnn wildcard that the parser will accept. 134 ** If the value exceeds 32767 then extra space is required for the Expr 135 ** structure. But otherwise, we believe that the number can be as large 136 ** as a signed 32-bit integer can hold. 137 */ 138 #ifndef SQLITE_MAX_VARIABLE_NUMBER 139 # define SQLITE_MAX_VARIABLE_NUMBER 32766 140 #endif 141 142 /* Maximum page size. The upper bound on this value is 65536. This a limit 143 ** imposed by the use of 16-bit offsets within each page. 144 ** 145 ** Earlier versions of SQLite allowed the user to change this value at 146 ** compile time. This is no longer permitted, on the grounds that it creates 147 ** a library that is technically incompatible with an SQLite library 148 ** compiled with a different limit. If a process operating on a database 149 ** with a page-size of 65536 bytes crashes, then an instance of SQLite 150 ** compiled with the default page-size limit will not be able to rollback 151 ** the aborted transaction. This could lead to database corruption. 152 */ 153 #ifdef SQLITE_MAX_PAGE_SIZE 154 # undef SQLITE_MAX_PAGE_SIZE 155 #endif 156 #define SQLITE_MAX_PAGE_SIZE 65536 157 158 159 /* 160 ** The default size of a database page. 161 */ 162 #ifndef SQLITE_DEFAULT_PAGE_SIZE 163 # define SQLITE_DEFAULT_PAGE_SIZE 4096 164 #endif 165 #if SQLITE_DEFAULT_PAGE_SIZE>SQLITE_MAX_PAGE_SIZE 166 # undef SQLITE_DEFAULT_PAGE_SIZE 167 # define SQLITE_DEFAULT_PAGE_SIZE SQLITE_MAX_PAGE_SIZE 168 #endif 169 170 /* 171 ** Ordinarily, if no value is explicitly provided, SQLite creates databases 172 ** with page size SQLITE_DEFAULT_PAGE_SIZE. However, based on certain 173 ** device characteristics (sector-size and atomic write() support), 174 ** SQLite may choose a larger value. This constant is the maximum value 175 ** SQLite will choose on its own. 176 */ 177 #ifndef SQLITE_MAX_DEFAULT_PAGE_SIZE 178 # define SQLITE_MAX_DEFAULT_PAGE_SIZE 8192 179 #endif 180 #if SQLITE_MAX_DEFAULT_PAGE_SIZE>SQLITE_MAX_PAGE_SIZE 181 # undef SQLITE_MAX_DEFAULT_PAGE_SIZE 182 # define SQLITE_MAX_DEFAULT_PAGE_SIZE SQLITE_MAX_PAGE_SIZE 183 #endif 184 185 186 /* 187 ** Maximum number of pages in one database file. 188 ** 189 ** This is really just the default value for the max_page_count pragma. 190 ** This value can be lowered (or raised) at run-time using that the 191 ** max_page_count macro. 192 */ 193 #ifndef SQLITE_MAX_PAGE_COUNT 194 # define SQLITE_MAX_PAGE_COUNT 1073741823 195 #endif 196 197 /* 198 ** Maximum length (in bytes) of the pattern in a LIKE or GLOB 199 ** operator. 200 */ 201 #ifndef SQLITE_MAX_LIKE_PATTERN_LENGTH 202 # define SQLITE_MAX_LIKE_PATTERN_LENGTH 50000 203 #endif 204 205 /* 206 ** Maximum depth of recursion for triggers. 207 ** 208 ** A value of 1 means that a trigger program will not be able to itself 209 ** fire any triggers. A value of 0 means that no trigger programs at all 210 ** may be executed. 211 */ 212 #ifndef SQLITE_MAX_TRIGGER_DEPTH 213 # define SQLITE_MAX_TRIGGER_DEPTH 1000 214 #endif 215