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Overview
| SHA1 Hash: | ae2879358de6363fda764098e04a4bef4124765e |
|---|---|
| Date: | 2010-02-12 18:34:09 |
| User: | drh |
| Comment: | Update the documentation to include information about the new secure_delete pragma. |
Tags And Properties
- branch=trunk inherited from [b2e03e19ab]
- sym-trunk inherited from [b2e03e19ab]
Changes
Changes to pages/compile.in
165 SQLite will automatically invoke [sqlite3_os_init()] when it initializes. 165 SQLite will automatically invoke [sqlite3_os_init()] when it initializes. 166 166 167 This option is typically used when building SQLite for an embedded 167 This option is typically used when building SQLite for an embedded 168 platform with a custom operating system. 168 platform with a custom operating system. 169 } 169 } 170 170 171 COMPILE_OPTION {SQLITE_SECURE_DELETE} { 171 COMPILE_OPTION {SQLITE_SECURE_DELETE} { 172 This compile-time option causes SQLite to overwrite deleted | 172 This compile-time option changes the default setting of the 173 information with zeros in addition to marking the space | 173 [secure_delete pragma]. When this option is not used, secure_delete defaults 174 as available for reuse. Without this option, deleted data | 174 to off. When this option is present, secure_delete defaults to on. 175 might be recoverable from a database using a binary editor. < 176 However, there is a performance penalty for using this option. < 177 175 178 This option does <u>not</u> cause deleted data is securely | 176 The secure_delete setting causes deleted content to be overwritten with 179 removed from the underlying storage media. | 177 zeros. There is a small performance penalty for this since additional I/O > 178 must occur. On the other hand, secure_delete can prevent sensitive > 179 information from lingering in unused parts of the database file after it > 180 has allegedly been deleted. See the documentation on the > 181 [secure_delete pragma] for additional information. 180 } 182 } 181 183 182 COMPILE_OPTION {SQLITE_THREADSAFE=<i><0 or 1 or 2></i>} { 184 COMPILE_OPTION {SQLITE_THREADSAFE=<i><0 or 1 or 2></i>} { 183 This option controls whether or not code is included in SQLite to 185 This option controls whether or not code is included in SQLite to 184 enable it to operate safely in a multithreaded environment. The 186 enable it to operate safely in a multithreaded environment. The 185 default is SQLITE_THREADSAFE=1 which is safe for use in a multithreaded 187 default is SQLITE_THREADSAFE=1 which is safe for use in a multithreaded 186 environment. When compiled with SQLITE_THREADSAFE=0 all mutexing code 188 environment. When compiled with SQLITE_THREADSAFE=0 all mutexing code
Changes to pages/pragma.in
627 output order might malfunction. By running the application multiple 627 output order might malfunction. By running the application multiple 628 times with this pragma both disabled and enabled, cases where the 628 times with this pragma both disabled and enabled, cases where the 629 application makes faulty assumptions about output order can be 629 application makes faulty assumptions about output order can be 630 identified and fixed early, reducing problems 630 identified and fixed early, reducing problems 631 that might be caused by linking against a different version of SQLite. 631 that might be caused by linking against a different version of SQLite. 632 </p> 632 </p> 633 </li> 633 </li> > 634 > 635 <tcl>Subsection secure_delete</tcl> > 636 <li><p>^(<b>PRAGMA secure_delete; > 637 <br>PRAGMA secure_delete = </b><i>boolean</i><b>;</b></p> > 638 <p>Query or change the secure-delete flag.)^ ^When the secure-delete > 639 flag is on, SQLite overwrites deleted content with zeros. The default > 640 setting is determined by the [SQLITE_SECURE_DELETE] > 641 compile-time option. > 642 > 643 <p> > 644 ^This pragma sets or clears the secure-delete flag when the pragma is > 645 prepared, not when the resulting prepared statement is run. ^The > 646 prepared statement for this pragma merely returns the value of the > 647 secure-delete flag at the time the statement was prepared. One should > 648 not retain the prepared statement for this pragma. > 649 > 650 <p> > 651 ^When there are [ATTACH | attached databases], this pragma only changes > 652 the secure-delete flag for the one database specified in the pragma, or > 653 for the main database if no database is specified. > 654 ^To change the secure-delete flag on all attached databases, this > 655 pragma must be run separately for each attached datatabase. > 656 > 657 <p> > 658 ^When multiple database connections share the same cache, changing > 659 the secure-delete flag on one database connection changes it for them > 660 all. > 661 </p> > 662 </li> 634 663 635 <tcl>Subsection short_column_names</tcl> 664 <tcl>Subsection short_column_names</tcl> 636 <li><p>^(<b>PRAGMA short_column_names; 665 <li><p>^(<b>PRAGMA short_column_names; 637 <br>PRAGMA short_column_names = </b><i>boolean</i><b>;</b></p> 666 <br>PRAGMA short_column_names = </b><i>boolean</i><b>;</b></p> 638 <p>Query or change the short-column-names flag.)^ ^This flag affects 667 <p>Query or change the short-column-names flag.)^ ^This flag affects 639 the way SQLite names columns of data returned by [SELECT] statements. 668 the way SQLite names columns of data returned by [SELECT] statements. 640 See the [full_column_names] pragma for full details. 669 See the [full_column_names] pragma for full details.