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Overview
Comment: | Add the new Kreibich book. Add preliminary documentation on WAL pragmas. Refactor the pragma.html document. |
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f1676af6d8151947d54cf0ad84d10238 |
User & Date: | drh 2010-05-07 02:46:29.000 |
Context
2010-05-07
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16:18 | Fleshing out the WAL documentation. (check-in: a7c7d3a520 user: drh tags: trunk) | |
02:46 | Add the new Kreibich book. Add preliminary documentation on WAL pragmas. Refactor the pragma.html document. (check-in: f1676af6d8 user: drh tags: trunk) | |
2010-05-06
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23:48 | Minor edits on the way toward 3.7.0 documentation. The wal.html document is created but is still mostly just a stub. (check-in: 019b60379f user: drh tags: trunk) | |
Changes
Added images/books/kreibich.gif.
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Changes to pages/about.in.
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9 10 11 12 13 14 15 | <li> <a href="features.html">Features</a> </li> <li> <a href="faq.html">Frequently Asked Questions</a> </li> <li> <a href="famous.html">Well-known Users</a> </li> <li> <a href="books.html">Books About SQLite</a> </li> <li> <a href="quickstart.html">Getting Started</a> </li> <li> <a href="lang.html">SQL Syntax</a> <ul> | | | 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | <li> <a href="features.html">Features</a> </li> <li> <a href="faq.html">Frequently Asked Questions</a> </li> <li> <a href="famous.html">Well-known Users</a> </li> <li> <a href="books.html">Books About SQLite</a> </li> <li> <a href="quickstart.html">Getting Started</a> </li> <li> <a href="lang.html">SQL Syntax</a> <ul> <li> <a href="pragma.html#toc">Pragmas</a> <li> <a href="lang_corefunc.html">SQL functions</a> <li> <a href="lang_datefunc.html">Date & time functions</a> <li> <a href="lang_aggfunc.html">Aggregate functions</a> </ul> </li> <li> <a href="c3ref/intro.html">C/C++ Interface Spec</a> <ul> |
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1 2 3 4 5 6 7 8 9 10 11 12 | <title>Books About SQLite</title> <tcl>hd_keywords {books about SQLite}</tcl> <h1 align=center>Books About SQLite</h1> <hr> <table border=0> <tr><td valign=top><img src="images/books/symbiansql.jpg"><td valign=top> <h2>Inside Symbian SQL (2010)</h2> <p>Authors: Ivan Litovski & Richard Maynard<br> Publisher: Wiley<br> | > > > > > > > > > > > > > > > > > > > > > > > > > > > > | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 | <title>Books About SQLite</title> <tcl>hd_keywords {books about SQLite}</tcl> <h1 align=center>Books About SQLite</h1> <hr> <table border=0><tr><td valign=top><p><img src="images/books/kreibich.gif"> <td valign=top> <h2>Using SQLite (2010)</h2> <p> Author: Jay A. Kreibich<br> Publisher: O'Reilly Media<br> <a href="http://oreilly.com/catalog/9780596521196/">O'Reilly</a></p> <p>Developers, take note: databases aren't just for the IS group any more. You can build database-backed applications for the desktop, Web, embedded systems, or operating systems without linking to heavy-duty client-server databases such as Oracle and MySQL. This book shows how you to use SQLite, a small and lightweight database that you can build right into your application during development. Applications that handle data have an enormous advantage today, and with SQLite, you'll discover how to develop a database-backed application that remains manageable in size and complexity. This book guides you every step of the way. You'll get a crash course in data modeling, become familiar with SQLite's dialect of the SQL database language, and learn how you to work with SQLite using either a scripting language or a C-based language, such as C# or Objective C.Now, even relatively small and nimble applications can be a part of the data revolution. Using SQLite shows you how. </p> </table> <hr> <table border=0> <tr><td valign=top><img src="images/books/symbiansql.jpg"><td valign=top> <h2>Inside Symbian SQL (2010)</h2> <p>Authors: Ivan Litovski & Richard Maynard<br> Publisher: Wiley<br> |
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60 61 62 63 64 65 66 | <p>This text is written in fluent Japanese specifically for a Japanese audience. This is the second edition of the book - the first edition was published in 2005. </p> </table> <hr> | | | 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 | <p>This text is written in fluent Japanese specifically for a Japanese audience. This is the second edition of the book - the first edition was published in 2005. </p> </table> <hr> <table border=0><tr><td valign=top><p><img src="images/books/haldar.gif"> <td valign=top> <h2>Inside SQLite (2007)</h2> <p> Author: Sibsankar Haldar<br> Publisher: O'Reilly Media<br> <a href="http://oreilly.com/catalog/9780596550066">O'Reilly</a></p> |
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91 92 93 94 95 96 97 | <p><ul> <li> <a href="features.html">Features</a> </li> <li> <a href="faq.html">Frequently Asked Questions</a> </li> <li> <a href="famous.html">Well-known Users</a> </li> <li> <a href="quickstart.html">Getting Started</a> </li> <li> <a href="lang.html">SQL Syntax</a> <ul> | | | 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 | <p><ul> <li> <a href="features.html">Features</a> </li> <li> <a href="faq.html">Frequently Asked Questions</a> </li> <li> <a href="famous.html">Well-known Users</a> </li> <li> <a href="quickstart.html">Getting Started</a> </li> <li> <a href="lang.html">SQL Syntax</a> <ul> <li> <a href="pragma.html#toc">Pragmas</a> <li> <a href="lang_corefunc.html">SQL functions</a> <li> <a href="lang_datefunc.html">Date & time functions</a> <li> <a href="lang_aggfunc.html">Aggregate functions</a> </ul> </li> <li> <a href="c3ref/intro.html">C/C++ Interface Spec</a> <ul> |
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Changes to pages/pragma.in.
1 2 3 4 5 6 7 8 9 10 11 | <title>Pragma statements supported by SQLite</title> <tcl> proc Section {name {label {}} {keywords {}}} { hd_puts "\n<hr />" if {$label!=""} { hd_fragment $label if {$keywords!=""} { eval hd_keywords $keywords } } | > | > | > > > | | > | | > > > > > | | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 | <title>Pragma statements supported by SQLite</title> <h1 align="center">PRAGMA Statements</h1> <tcl> proc Section {name {label {}} {keywords {}}} { hd_puts "\n<hr />" if {$label!=""} { hd_fragment $label if {$keywords!=""} { eval hd_keywords $keywords } } hd_puts "<h2>$name</h2>\n" } unset -nocomplain PragmaBody PragmaRef PragmaDud PragmaKeys # Each pragma is recorded by invoking this procedure. proc Pragma {namelist content} { global PragmaBody PragmaRef PragmaKeys set main_name [lindex $namelist 0] set PragmaBody($main_name) $content set PragmaKeys($main_name) $namelist foreach x $namelist { set PragmaRef($x) $main_name } } # Legacy pragma proc LegacyPragma {namelist content} { Pragma $namelist $content global PragmaLegacy foreach x $namelist {set PragmaLegacy($x) 1} } </tcl> <p>The PRAGMA statement is a SQL extension specific to SQLite and used to modify the operation of the SQLite library or to query the SQLite library for internal (non-table) data. The PRAGMA statement is issued using the same interface as other SQLite commands (e.g. [SELECT], [INSERT]) but is different in the following important respects: |
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42 43 44 45 46 47 48 | SQL statements. Whether or not the pragma runs during sqlite3_prepare() or sqlite3_step() depends on the pragma and on the specific release of SQLite. <li>The pragma command is specific to SQLite and is very unlikely to be compatible with any other SQL database engine. </ul> | < < < < < < < < < < < < < < | 53 54 55 56 57 58 59 60 61 62 63 64 65 66 | SQL statements. Whether or not the pragma runs during sqlite3_prepare() or sqlite3_step() depends on the pragma and on the specific release of SQLite. <li>The pragma command is specific to SQLite and is very unlikely to be compatible with any other SQL database engine. </ul> <tcl> Section {PRAGMA command syntax} syntax {PRAGMA} BubbleDiagram pragma-stmt BubbleDiagram pragma-value </tcl> |
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88 89 90 91 92 93 94 | <p>^A pragma may have an optional database name before the pragma name. ^The database name is the name of an [ATTACH]-ed database or it can be "main" or "temp" for the main and the TEMP databases. ^If the optional database name is omitted, "main" is assumed. ^In some pragmas, the database name is meaningless and is simply ignored.</p> | < < < | | | < > < | > | | | 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 | <p>^A pragma may have an optional database name before the pragma name. ^The database name is the name of an [ATTACH]-ed database or it can be "main" or "temp" for the main and the TEMP databases. ^If the optional database name is omitted, "main" is assumed. ^In some pragmas, the database name is meaningless and is simply ignored.</p> <tcl>Pragma {automatic_index} { <p>^(<b>PRAGMA automatic_index; <br>PRAGMA automatic_index = </b><i>boolean</i><b>;</b></p> <p>Query, set, or clear the [automatic indexing] capability.)^ <p>^[Automatic indexing] is enabled by default. ^This pragma only influences the query plan as statements are prepared or reprepared. Existing prepared statements must be reprepared for a change in the automatic_index setting to affect their operation. } Pragma {auto_vacuum} { <p><b>PRAGMA auto_vacuum;<br> PRAGMA auto_vacuum = </b> <i>0 | NONE | 1 | FULL | 2 | INCREMENTAL</i><b>;</b></p> <p>Query or set the auto-vacuum status in the database.</p> <p>^The default setting for auto-vacuum is 0 or "none", unless the [SQLITE_DEFAULT_AUTOVACUUM] compile-time option is used. |
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158 159 160 161 162 163 164 | reorganize the entire database file. ^To change from "full" or "incremental" back to "none" always requires running [VACUUM] even on an empty database. </p> <p>^When the auto_vacuum pragma is invoked with no arguments, it returns the current auto_vacuum mode.</p> | < | > | | | | > | | < | > | | | | > | | | | | | | | | | 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 | reorganize the entire database file. ^To change from "full" or "incremental" back to "none" always requires running [VACUUM] even on an empty database. </p> <p>^When the auto_vacuum pragma is invoked with no arguments, it returns the current auto_vacuum mode.</p> } Pragma cache_size { <p>^(<b>PRAGMA cache_size; <br>PRAGMA cache_size = </b><i>Number-of-pages</i><b>;</b></p> <p>Query or change the suggested maximum number of database disk pages that SQLite will hold in memory at once per open database file.)^ ^Whether or not this suggestion is honored is at the discretion of the [sqlite3_pcache_methods | Application Defined Page Cache]. ^In the default page cache implemention, the suggested cache size is honored as long as it is 10 or greater. ^A suggested cache size of less than 10 are treated as if it were 10. ^Alternative application-defined page cache implementations may choose to interpret the suggested cache size in different ways or to ignore it all together. ^The default suggested cache size is 2000.</p> <p>^When you change the cache size using the cache_size pragma, the change only endures for the current session. ^The cache size reverts to the default value when the database is closed and reopened. Use the [default_cache_size] pragma to check the cache size permanently.</p> } Pragma case_sensitive_like { <p>^(<b>PRAGMA case_sensitive_like = </b><i>boolean</i><b>;</b>)^</p> <p>^The default behavior of the [LIKE] operator is to ignore case for ASCII characters. ^Hence, by default <b>'a' LIKE 'A'</b> is true. ^The case_sensitive_like pragma installs a new application-defined LIKE function that can change this behavior. ^When case_sensitive_like is enabled, <b>'a' LIKE 'A'</b> is false but <b>'a' LIKE 'a'</b> is still true.</p> <p>^This pragma only works if the [like | built-in like() SQL function] has not been overloaded using [sqlite3_create_function()].</p> } Pragma count_changes { <p>^(<b>PRAGMA count_changes; <br>PRAGMA count_changes = </b>boolean</i><b>;</b></p> <p>Query or change the count-changes flag.)^ ^Normally, when the count-changes flag is not set, [INSERT], [UPDATE] and [DELETE] statements return no data. ^When count-changes is set, each of these commands returns a single row of data consisting of one integer value - the number of rows inserted, modified or deleted by the command. ^The returned change count does not include any insertions, modifications or deletions performed by triggers, or any changes made automatically by [foreign key actions].</p> <p>Another way to get the row change counts is to use the [sqlite3_changes()] or [sqlite3_total_changes()] interfaces. There is a subtle different, though. ^When an INSERT, UPDATE, or DELETE is run against a view using an [INSTEAD OF trigger], the count_changes pragma reports the number of rows in the view that fired the trigger, whereas [sqlite3_changes()] and [sqlite3_total_changes()] do not. } LegacyPragma default_cache_size { ^(<b>PRAGMA default_cache_size; <br>PRAGMA default_cache_size = </b><i>Number-of-pages</i><b>;</b></p> <p>This pragma queries or sets the suggested maximum number of pages of disk cache that will be allocated per open database file.)^ ^The difference between this pragma and [cache_size] is that the value set here persists across database connections. </p> } LegacyPragma empty_result_callbacks { <p><b>PRAGMA empty_result_callbacks; <br>PRAGMA empty_result_callbacks = </b><i>boolean</i><b>;</b></p> <p>Query or change the empty-result-callbacks flag.</p> <p>The empty-result-callbacks flag affects the [sqlite3_exec()] API only. Normally, when the empty-result-callbacks flag is cleared, the callback function supplied to the [sqlite3_exec()] is not invoked for commands that return zero rows of data. When empty-result-callbacks is set in this situation, the callback function is invoked exactly once, with the third parameter set to 0 (NULL). This is to enable programs that use the [sqlite3_exec()] API to retrieve column-names even when a query returns no data.</p> <p>This pragma is legacy. It was created long ago in the early days of SQLite before the prepared statement interface was available. Do not use this pragma. It is likely to go away in a future release</p> } Pragma encoding { <p>^(<b>PRAGMA encoding; <br>PRAGMA encoding = "UTF-8"; <br>PRAGMA encoding = "UTF-16"; <br>PRAGMA encoding = "UTF-16le"; <br>PRAGMA encoding = "UTF-16be";</b>)^</p> <p>^In first form, if the main database has already been created, then this pragma returns the text encoding used by the main database, one of "UTF-8", "UTF-16le" (little-endian UTF-16 |
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270 271 272 273 274 275 276 | and subsequent forms are used after the database file has already been created, they have no effect and are silently ignored.</p> <p>^Once an encoding has been set for a database, it cannot be changed.</p> <p>^Databases created by the [ATTACH] command always use the same encoding as the main database.</p> | < | > | | < | > | | < | > | | < | > | | < | > | | | 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 | and subsequent forms are used after the database file has already been created, they have no effect and are silently ignored.</p> <p>^Once an encoding has been set for a database, it cannot be changed.</p> <p>^Databases created by the [ATTACH] command always use the same encoding as the main database.</p> } Pragma foreign_keys { <p>^(<b>PRAGMA foreign_keys; <br>PRAGMA foreign_keys = </b><i>boolean</i><b>;</b></p> <p>Query, set, or clear the enforcement of [foreign key constraints].)^ <p>^This pragma is a no-op within a transaction; foreign key constraint enforcement may only be enabled or disabled when there is no pending [BEGIN] or [SAVEPOINT]. <p>^Changing the foreign_keys setting affects the execution of all statements prepared using the database connection, including those prepared before the setting was changed. ^Any existing statements prepared using the legacy [sqlite3_prepare()] interface may fail with an [SQLITE_SCHEMA] error after the foreign_keys setting is changed. <p>^(As of SQLite [version 3.6.19], the default setting for foreign key enforcement is OFF.)^ However, that might change in a future release of SQLite. To minimize future problems, applications should set the foreign key enforcement flag as required by the application and not depend on the default setting. } LegacyPragma full_column_names { <p>^(<b>PRAGMA full_column_names; <br>PRAGMA full_column_names = </b><i>boolean</i><b>;</b></p> <p>Query or change the full_column_names flag.)^ ^This flag together with the [short_column_names] flag determine the way SQLite assigns names to result columns of [SELECT] statements. ^(Result columns are named by applying the following rules in order: <ol> <li><p>If there is an AS clause on the result, then the name of the column is the right-hand side of the AS clause.</p></li> <li><p>If the result is a general expression, not a just the name of a source table column, then the name of the result is a copy of the expression text.</p></li> <li><p>If the [short_column_names] pragma is ON, then the name of the result is the name of the source table column without the source table name prefix: COLUMN.</p></li> <li><p>If both pragmas [short_column_names] and [full_column_names] are OFF then case (2) applies. </p></li> <li><p>The name of the result column is a combination of the source table and source column name: TABLE.COLUMN</p></li> </ol>)^ } Pragma fullfsync { <p>^(<b>PRAGMA fullfsync <br>PRAGMA fullfsync = </b><i>boolean</i><b>;</b></p> <p>Query or change the fullfsync flag.)^ ^This flag affects determines whether or not the F_FULLFSYNC syncing method is used on systems that support it. ^The default value of the fullfsync flag is off. Only Mac OS X supports F_FULLFSYNC. </p> } Pragma incremental_vacuum { <p><b>PRAGMA incremental_vacuum</b><i>(N)</i><b>;</b></p> <p>^The incremental_vacuum pragma causes up to <i>N</i> pages to be removed from the freelist. ^The database file is truncated by the same amount. ^The incremental_vacuum pragma has no effect if the database is not in <a href="#pragma_auto_vacuum">auto_vacuum==incremental</a> mode or if there are no pages on the freelist. ^If there are fewer than <i>N</i> pages on the freelist, or if <i>N</i> is less than 1, or if <i>N</i> is omitted entirely, then the entire freelist is cleared.</p> <p>As of [version 3.4.0] (the first version that supports incremental_vacuum) this feature is still experimental. Possible future changes include enhancing incremental vacuum to do defragmentation and node repacking just as the full-blown [VACUUM] command does. And incremental vacuum may be promoted from a pragma to a separate SQL command, or perhaps some variation on the [VACUUM] command. Programmers are cautioned to not become enamored with the current syntax or functionality as it is likely to change.</p> } Pragma journal_mode { <p>^(<b>PRAGMA journal_mode; <br>PRAGMA </b><i>database</i><b>.journal_mode; <br>PRAGMA journal_mode = <i>DELETE | TRUNCATE | PERSIST | MEMORY | WAL | OFF</i> <br>PRAGMA </b><i>database</i><b>.journal_mode = <i>DELETE | TRUNCATE | PERSIST | MEMORY | WAL | OFF</i></b></p> <p>This pragma queries or sets the journal mode for databases |
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426 427 428 429 430 431 432 | set, then the database file will very likely go corrupt.</p> <p>^Note that the journal_mode for an [in-memory database] is either MEMORY or OFF and can not be changed to a different value. ^An attempt to change the journal_mode of an [in-memory database] to any setting other than MEMORY or OFF is ignored. ^Note also that the journal_mode cannot be changed while a transaction is active.</p> | < | > | | | 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 | set, then the database file will very likely go corrupt.</p> <p>^Note that the journal_mode for an [in-memory database] is either MEMORY or OFF and can not be changed to a different value. ^An attempt to change the journal_mode of an [in-memory database] to any setting other than MEMORY or OFF is ignored. ^Note also that the journal_mode cannot be changed while a transaction is active.</p> } Pragma journal_size_limit { <p><b> PRAGMA journal_size_limit<br> PRAGMA journal_size_limit = </b><i>N</i> <b>;</b> <p>^If a database connection is operating in either "exclusive mode" (PRAGMA locking_mode=exclusive) or "persistent journal mode" (PRAGMA journal_mode=persist) then under certain circumstances after committing a transaction the journal file may remain in |
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461 462 463 464 465 466 467 | [SQLITE_DEFAULT_JOURNAL_SIZE_LIMIT] at compile time.</p> <p>^This pragma only operates on the single database specified prior to the pragma name (or on the "main" database if no database is specified.) There is no way to operate on all attached databases using a single PRAGMA statement, nor is there a way to set the limit to use for databases that will be attached in the future. | < | > | | < | > | | | 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 | [SQLITE_DEFAULT_JOURNAL_SIZE_LIMIT] at compile time.</p> <p>^This pragma only operates on the single database specified prior to the pragma name (or on the "main" database if no database is specified.) There is no way to operate on all attached databases using a single PRAGMA statement, nor is there a way to set the limit to use for databases that will be attached in the future. } Pragma legacy_file_format { <p>^(<b>PRAGMA legacy_file_format; <br>PRAGMA legacy_file_format = <i>boolean</i></b></p> <p>This pragma sets or queries the value of the legacy_file_format flag.)^ ^When this flag is on, new SQLite databases are created in a file format that is readable and writable by all versions of SQLite going back to 3.0.0. ^When the flag is off, new databases are created using the latest file format which might not be readable or writable by versions of SQLite prior to 3.3.0.</p> <p>^When the legacy_file_format pragma is issued with no argument, it returns the setting of the flag. ^This pragma does <u>not</u> tell which file format the current database is using; it tells what format will be used by any newly created databases.</p> <p>^(This flag only affects newly created databases. It has no effect on databases that already exist.)^</p> <p>^The default file format is set by the [SQLITE_DEFAULT_FILE_FORMAT] compile-time option.</p> } Pragma locking_mode { <p>^(<b>PRAGMA locking_mode; <br>PRAGMA locking_mode = <i>NORMAL | EXCLUSIVE</i></b>)^</p> <p>^This pragma sets or queries the database connection locking-mode. ^The locking-mode is either NORMAL or EXCLUSIVE. <p>^In NORMAL locking-mode (the default), a database connection unlocks the database file at the conclusion of each read or write transaction. ^When the locking-mode is set to EXCLUSIVE, the |
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531 532 533 534 535 536 537 | <p>^The "temp" database (in which TEMP tables and indices are stored) and [in-memory databases] always uses exclusive locking mode. ^The locking mode of temp and [in-memory databases] cannot be changed. ^All other databases use the normal locking mode by default and are affected by this pragma.</p> | < | > | | | 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 | <p>^The "temp" database (in which TEMP tables and indices are stored) and [in-memory databases] always uses exclusive locking mode. ^The locking mode of temp and [in-memory databases] cannot be changed. ^All other databases use the normal locking mode by default and are affected by this pragma.</p> } Pragma page_size { <p>^(<b>PRAGMA page_size; <br>PRAGMA page_size = </b><i>bytes</i><b>;</b></p> <p>Query or set the page size of the database.)^ ^The page size may only be set if the database has not yet been created. ^The page size must be a power of two greater than or equal to 512 and less than or equal to [SQLITE_MAX_PAGE_SIZE]. The maximum value for [SQLITE_MAX_PAGE_SIZE] is 32768. </p> |
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573 574 575 576 577 578 579 | running on workstations is for atomic write to be disabled, for the maximum page size to be set to 32768, for SQLITE_DEFAULT_PAGE_SIZE to be 1024, and for the maximum default page size to be set to 8192. ^(The default xSectorSize method on workstation implementations always reports a sector size of 512 bytes. Hence, the default page size chosen by SQLite is usually 1024 bytes.)^</p> | < | > | | < | > | | < | > | | < | > | | < | > | | | 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 | running on workstations is for atomic write to be disabled, for the maximum page size to be set to 32768, for SQLITE_DEFAULT_PAGE_SIZE to be 1024, and for the maximum default page size to be set to 8192. ^(The default xSectorSize method on workstation implementations always reports a sector size of 512 bytes. Hence, the default page size chosen by SQLite is usually 1024 bytes.)^</p> } Pragma max_page_count { <p>^(<b>PRAGMA max_page_count; <br>PRAGMA max_page_count = </b><i>N</i><b>;</b></p> <p>Query or set the maximum number of pages in the database file.)^ ^Both forms of the pragma return the maximum page count. ^The second form attempts to modify the maximum page count. ^The maximum page count cannot be reduced below the current database size. </p> } Pragma read_uncommitted { <p>^(<b>PRAGMA read_uncommitted; <br>PRAGMA read_uncommitted = </b><i>boolean</i><b>;</b></p> <p>Query, set, or clear READ UNCOMMITTED isolation.)^ ^The default isolation level for SQLite is SERIALIZABLE. ^Any process or thread can select READ UNCOMMITTED isolation, but SERIALIZABLE will still be used except between connections that share a common page and schema cache. Cache sharing is enabled using the [sqlite3_enable_shared_cache()] API. Cache sharing is disabled by default. </p> <p>See [SQLite Shared-Cache Mode] for additional information.</p> } Pragma recursive_triggers { <p>^(<b>PRAGMA recursive_triggers; <br>PRAGMA recursive_triggers = </b><i>boolean</i><b>;</b></p> <p>Query, set, or clear the recursive trigger capability.)^ <p>^Changing the recursive_triggers setting affects the execution of all statements prepared using the database connection, including those prepared before the setting was changed. ^Any existing statements prepared using the legacy [sqlite3_prepare()] interface may fail with an [SQLITE_SCHEMA] error after the recursive_triggers setting is changed. <p>Prior to SQLite version 3.6.18, recursive triggers were not supported. The behavior of SQLite was always as if this pragma was set to OFF. Support for recursive triggers was added in version 3.6.18 but was initially turned OFF by default, for compatibility. Recursive triggers may be turned on by default in future versions of SQLite. </p> <p>^(The depth of recursion for triggers has a hard upper limit set by the [SQLITE_MAX_TRIGGER_DEPTH] compile-time option and a run-time limit set by [sqlite3_limit](db,[SQLITE_LIMIT_TRIGGER_DEPTH],...).)^</p> } Pragma reverse_unordered_selects { <p>^(<b>PRAGMA reverse_unordered_selects; <br>PRAGMA reverse_unordered_selects = </b><i>boolean</i><b>;</b>)^</p> <p>^When enabled, this PRAGMA causes [SELECT] statements without a an ORDER BY clause to emit their results in the reverse order of what they normally would. This can help debug applications that are making invalid assumptions about the result order.<p>SQLite makes no guarantees about the order of results if a SELECT omits the ORDER BY clause. Even so, the order of results does not change from one run to the next, and so many applications mistakenly come to depend on the arbitrary output order whatever that order happens to be. However, sometimes new versions of SQLite will contain optimizer enhancements that will cause the output order of queries without ORDER BY clauses to shift. When that happens, applications that depend on a certain output order might malfunction. By running the application multiple times with this pragma both disabled and enabled, cases where the application makes faulty assumptions about output order can be identified and fixed early, reducing problems that might be caused by linking against a different version of SQLite. </p> } Pragma secure_delete { <p>^(<b>PRAGMA secure_delete; <br>PRAGMA </b><i>database</i><b>.secure_delete; <br>PRAGMA secure_delete = </b><i>boolean</i><b> <br>PRAGMA </b><i>database</i><b>.secure_delete = </b><i>boolean</i></p> <p>Query or change the secure-delete setting.)^ ^When secure-delete on, SQLite overwrites deleted content with zeros. ^The default setting is determined by the [SQLITE_SECURE_DELETE] |
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668 669 670 671 672 673 674 | of the main database at the time the ATTACH command is evaluated. <p> ^When multiple database connections share the same cache, changing the secure-delete flag on one database connection changes it for them all. </p> | < | > | | < | > | | | 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 | of the main database at the time the ATTACH command is evaluated. <p> ^When multiple database connections share the same cache, changing the secure-delete flag on one database connection changes it for them all. </p> } LegacyPragma short_column_names { <p>^(<b>PRAGMA short_column_names; <br>PRAGMA short_column_names = </b><i>boolean</i><b>;</b></p> <p>Query or change the short-column-names flag.)^ ^This flag affects the way SQLite names columns of data returned by [SELECT] statements. See the [full_column_names] pragma for full details. </p> } Pragma synchronous { <p>^(<b>PRAGMA synchronous; <br>PRAGMA synchronous = </b> <i>0 | OFF | 1 | NORMAL | 2 | FULL</i><b>;</b></p> <p>Query or change the setting of the "synchronous" flag.)^ ^The first (query) form will return the synchronous setting as an integer. ^When synchronous is FULL (2), the SQLite database engine will pause at critical moments to make sure that data has actually been |
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709 710 711 712 713 714 715 | the database might become corrupted if the operating system crashes or the computer loses power before that data has been written to the disk surface. On the other hand, some operations are as much as 50 or more times faster with synchronous OFF. </p> <p>^The default setting is synchronous=FULL. </p> | < | | | | 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 | the database might become corrupted if the operating system crashes or the computer loses power before that data has been written to the disk surface. On the other hand, some operations are as much as 50 or more times faster with synchronous OFF. </p> <p>^The default setting is synchronous=FULL. </p> } Pragma temp_store { <p>^(<b>PRAGMA temp_store; <br>PRAGMA temp_store = </b> <i>0 | DEFAULT | 1 | FILE | 2 | MEMORY</i><b>;</b></p> <p>Query or change the setting of the "<b>temp_store</b>" parameter.)^ ^When temp_store is DEFAULT (0), the compile-time C preprocessor macro [SQLITE_TEMP_STORE] is used to determine where temporary tables and indices are stored. ^When |
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767 768 769 770 771 772 773 | <td align="center">2</td> <td align="center">memory</td></tr> <tr><td align="center">3</td> <td align="center"><em>any</em></td> <td align="center">memory</td></tr> </table> </blockquote>)^ | < < | > | | | 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 | <td align="center">2</td> <td align="center">memory</td></tr> <tr><td align="center">3</td> <td align="center"><em>any</em></td> <td align="center">memory</td></tr> </table> </blockquote>)^ } LegacyPragma temp_store_directory { <p>^(<b>PRAGMA temp_store_directory; <br>PRAGMA temp_store_directory = '</b><i>directory-name</i><b>';</b></p> <p>Query or change the setting of the "temp_store_directory" - the directory where files used for storing [temporary tables] and indices are kept.</p>)^ <p>^When the temp_store_directory setting is changed, all existing temporary tables, indices, triggers, and viewers are immediately deleted. In |
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799 800 801 802 803 804 805 | error is raised if <i>directory-name</i> is not found or is not writable. </p> <p>The default directory for temporary files depends on the OS. Some OS interfaces may choose to ignore this variable in place temporary files in some other directory different from the directory specified here. In that sense, this pragma is only advisory.</p> | < < | < < | | | | > | | | | > | | | | > | | | | > | | | > | | | | > | | | | > | | | < | < < | | | 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 | error is raised if <i>directory-name</i> is not found or is not writable. </p> <p>The default directory for temporary files depends on the OS. Some OS interfaces may choose to ignore this variable in place temporary files in some other directory different from the directory specified here. In that sense, this pragma is only advisory.</p> } Pragma collation_list { <p>^(<b>PRAGMA collation_list;</b></p> <p>Return a list of the collating sequences defined for the current database connection.</p>)^ } Pragma database_list { <p>^(<b>PRAGMA database_list;</b></p> <p>This pragma works like a query to return one row for each database attached to the current database connection.)^ ^(Columns of the result set include the index and the name the database was attached with.)^ ^The first row will be for the main database. ^The second row will be for the database used to store temporary tables.</p> } LegacyPragma foreign_key_list { <p>^(<b>PRAGMA foreign_key_list(</b><i>table-name</i><b>);</b></p> <p>This pragma returns one rwo for each foreign key that references a column in the argument table.)^ } Pragma freelist_count { <p>^(<b>PRAGMA freelist_count;</b></p> <p>Return the number of unused pages in the database file.)^ ^Running a <a href="#pragma_incremental_vacuum">"PRAGMA incremental_vaccum(N);"</a> command with a large value of N will shrink the database file by this number of pages when incremental vacuum is enabled. </p> } Pragma index_info { <p>^(<b>PRAGMA index_info(</b><i>index-name</i><b>);</b></p> <p>This program returns one row row each column in the named index.</p>)^ } Pragma index_list { <p>^(<b>PRAGMA index_list(</b><i>table-name</i><b>);</b></p> <p>This pragma returns one row for each index associated with the given table.)^ ^Columns of the result set include the index name and a flag to indicate whether or not the index is UNIQUE. </p> } Pragma page_count { <p>^(<b>PRAGMA page_count;</b></p> <p>Return the total number of pages in the database file.</p>)^ } Pragma table_info { <p>^(<b>PRAGMA table_info(</b><i>table-name</i><b>);</b></p> <p>This pragma returns one row for each column in the named table.)^ ^Columns in the result set include the column name, data type, whether or not the column can be NULL, and the default value for the column.</p> } Pragma {schema_version user_version} { <p><b>PRAGMA schema_version; <br>PRAGMA schema_version = </b><i>integer </i><b>; <br>PRAGMA user_version; <br>PRAGMA user_version = </b><i>integer </i><b>;</b> <p> ^The pragmas schema_version and user_version are used to set or get the value of the schema-version and user-version, respectively. ^Both |
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881 882 883 884 885 886 887 | the schema of the database against which the compiled query is actually executed. ^Subverting this mechanism by using "PRAGMA schema_version" to modify the schema-version is potentially dangerous and may lead to program crashes or database corruption. Use with caution!</p> <p> ^The user-version is not used internally by SQLite. It may be used by applications for any purpose.</p> | < < | < < | | | | > | | | | > | | | | > | | | | > > > | > | | | > > > > > | | | > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > | > > > > > > > > > > > > > > > > > > > > > > > > > > | 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 | the schema of the database against which the compiled query is actually executed. ^Subverting this mechanism by using "PRAGMA schema_version" to modify the schema-version is potentially dangerous and may lead to program crashes or database corruption. Use with caution!</p> <p> ^The user-version is not used internally by SQLite. It may be used by applications for any purpose.</p> } Pragma compile_options { <p><b>PRAGMA compile_options;</b></p> <p>^This pragma returns the names of [compile-time options] used when building SQLite, one option per row. ^The "SQLITE_" prefix is omitted from the returned option names. See also the [sqlite3_compileoption_get()] C/C++ interface and the [sqlite_compileoption_get()] SQL functions.</p> } Pragma integrity_check { <p><b>PRAGMA integrity_check; <br>PRAGMA integrity_check(</b><i>integer</i><b>)</b></p> <p>^This pragma does an integrity check of the entire database. ^It looks for out-of-order records, missing pages, malformed records, and corrupt indices. ^If any problems are found, then strings are returned (as multiple rows with a single column per row) which describe the problems. ^At most <i>integer</i> errors will be reported before the analysis quits. ^The default value for <i>integer</i> is 100. ^If no errors are found, a single row with the value "ok" is returned.</p> } Pragma quick_check { <p><b>PRAGMA quick_check; <br>PRAGMA quick_check(</b><i>integer</i><b>)</b></p> <p>^The pragma is like [integrity_check] except that it does not verify that index content matches table content. By skipping the verification of index content, quick_check is able to run much faster than integrity_check. Otherwise the two pragmas are the same. </p> } Pragma parser_trace { <p><b>PRAGMA parser_trace = </b><i>boolean</i><b>; </b></p> <p>^Turn tracing of the SQL parser inside of the SQLite library on and off. This is used for debugging. This only works if the library is compiled with the SQLITE_DEBUG compile-time option.</p> <p>This PRAGMA is used to help test and debug the SQLite library itself. It is of little or not use to applications and is disabled if SQLite is not compiled with [SQLITE_DEBUG].</p> } Pragma vdbe_trace { <p><b>PRAGMA vdbe_trace = </b><i>boolean</i><b>;</b></p> <p>^Turn tracing of the virtual database engine inside of the SQLite library on and off. This is used for debugging. See the <a href="vdbe.html#trace">VDBE documentation</a> for more information.</p> <p>This PRAGMA is used to help test and debug the SQLite library itself. It is of little or not use to applications and is disabled if SQLite is not compiled with [SQLITE_DEBUG].</p> } Pragma vdbe_listing { <p><b>PRAGMA vdbe_listing = </b><i>boolean</i><b>;</b></p> <p>^Turn listings of virtual machine programs on and off. With listing is on, the entire content of a program is printed just prior to beginning execution. The statement executes normally after the listing is printed. This is used for debugging. See the <a href="vdbe.html#trace">VDBE documentation</a> for more information.</p> <p>This PRAGMA is used to help test and debug the SQLite library itself. It is of little or not use to applications and is disabled if SQLite is not compiled with [SQLITE_DEBUG].</p> } Pragma wal_checkpoint { <p><b>PRAGMA </b><i>database</i><b>.wal_checkpoint;</b></p> <p>^If the [write-ahead log] is enabled (via the [journal_mode pragma]), this pragma causes a checkpoint operation to run on database <i>database</i>, or on all attached databases if <i>database</i> is omitted. ^If [write-ahead log] is disabled, this pragma is a harmless no-op.</p> <p>^Invoking this pragma is equivalent to calling the [sqlite3_wal_checkpoint()] C interface.</p> } Pragma wal_autocheckpoint { <p><b>PRAGMA wal_autocheckpoint;<br> PRAGMA wal_autocheckpoint=</b><i>N</i><b>;</b></p> <p>^This pragma queries or sets the [write-ahead log] auto-checkpoint interval. When the [write-ahead log] is enabled (via the [journal_mode pragma]) a checkpoint will be run automatically whenever the write-ahead log equals or exceeds <i>N</i> pages in length. Setting the auto-checkpoint size to zero or a negative value turns auto-checkpointing off.</p> <p>^This pragma is a wrapper around the [sqlite3_wal_autocheckpoint()] C interface.</p> } Section {List Of PRAGMAs} {toc} {{pragma list}} </tcl> <table border=0 width="100%" cellpadding=10> <tr><td valign="top" align="left"><ul> <tcl> set allprag [lsort [array names PragmaRef]] set nprag [llength $allprag] set nrow [expr {($nprag+2)/3}] for {set i 0} {$i<$nprag} {incr i} { set prag [lindex $allprag $i] hd_puts "<li><a href=\"#pragma_$prag\">$prag</a>\n" if {$i%$nrow==($nrow-1) && $i+1<$nprag} { hd_puts "</ul></td><td valign=\"top\" align=\"left\"><ul>\n" } } </tcl> </ul></td></tr></table> <tcl> foreach prag [lsort [array names PragmaBody]] { hd_fragment pragma_$prag foreach x $PragmaKeys($prag) { hd_keywords *$x "PRAGMA $x" "$x pragma" } hd_puts "<hr>" hd_resolve $PragmaBody($prag) } </tcl> <hr> |
Changes to pages/sitemap.in.
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12 13 14 15 16 17 18 | <li> <a href="different.html">Distinctive Features</a> </li> <li> <a href="doclist.html">Alphabetical list of docs</a> </li> <li> <a href="books.html">Books About SQLite</a> </li> <li> <a href="keyword_index.html">Website Keyword Index</a> </li> </ul><td valign=top><ul> <li> <a href="lang.html">SQL Syntax</a> <ul> | | | 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 | <li> <a href="different.html">Distinctive Features</a> </li> <li> <a href="doclist.html">Alphabetical list of docs</a> </li> <li> <a href="books.html">Books About SQLite</a> </li> <li> <a href="keyword_index.html">Website Keyword Index</a> </li> </ul><td valign=top><ul> <li> <a href="lang.html">SQL Syntax</a> <ul> <li> <a href="pragma.html#toc">Pragmas</a> <li> <a href="lang_corefunc.html">SQL functions</a> <li> <a href="lang_datefunc.html">Date & time functions</a> <li> <a href="lang_aggfunc.html">Aggregate functions</a> </ul> <li> <a href="c3ref/intro.html">C/C++ Interface Spec</a> <ul> <li> <a href="cintro.html">Introduction</a> |
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Changes to pages/wal.in.
1 2 3 4 5 6 7 8 | <title>Write-Ahead Logging</title> <tcl>hd_keywords {WAL} {write-ahead log}</tcl> <h1 align="center">Write-Ahead Logging</h1> <p>The default method in which SQLite implements [atomic commit | atomic commit and rollback] is through the use of a [rollback journal]. | | | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 | <title>Write-Ahead Logging</title> <tcl>hd_keywords {WAL} {write-ahead log}</tcl> <h1 align="center">Write-Ahead Logging</h1> <p>The default method in which SQLite implements [atomic commit | atomic commit and rollback] is through the use of a [rollback journal]. Beginning with [version 3.7.0], a new write-ahead log option (hereafter referred to as "WAL") for implementing atomic commit and rollback is available as an option on some platforms.</p> <p>There are advantages and disadvantages to using WAL. We begin with a quick summary of advantages:</p> |
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