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| Comment: | Updates to the file format documentation. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
2d2c9fd38a782ec4a093262cc1503903 |
| User & Date: | drh 2010-07-05 15:06:41 |
|
2010-07-06
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| 01:27 | Adding first draft of WAL file format. (check-in: 05824b6e6a user: drh tags: trunk) | |
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2010-07-05
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| 15:06 | Updates to the file format documentation. (check-in: 2d2c9fd38a user: drh tags: trunk) | |
|
2010-06-29
| ||
| 16:05 | Fix a typo in the date/time function documentation. (check-in: cf14a52e82 user: drh tags: trunk) | |
Changes to pages/docs.in.
219 219 doc {VDBE Opcodes} {opcode.html} { 220 220 This document is an automatically generated description of the various 221 221 opcodes that the VDBE understands. Programmers can use this document as 222 222 a reference to better understand the output of EXPLAIN listings from 223 223 SQLite. 224 224 } 225 225 226 -doc {SQLite File Format} {fileformat.html} { 226 +doc {SQLite File Format} {fileformat2.html} { 227 227 A description of the format used for SQLite database and journal files, and 228 228 other details required to create software to read and write SQLite 229 229 databases without using SQLite. 230 230 } 231 231 232 -doc {File Format Redux} {fileformat2.html} { 233 - An alternative and independent description of the SQLite file format. 234 - This document provides an independent the same information and is 235 - compatible with the previous document, just in a different format. 232 +doc {SQLite File Format (first edition)} {fileformat.html} { 233 + An older and more verbose description of the SQLite file format. 234 + This document provides the same information and is 235 + compatible with the previous document. 236 236 } 237 237 238 238 doc {Compilation Options} {compile.html} { 239 239 This document describes the compile time options that may be set to 240 240 modify the default behavior of the library or omit optional features 241 241 in order to reduce binary size. 242 242 }
Changes to pages/fileformat.in.
1 1 <title>SQLite Database File Format</title> 2 2 <tcl> 3 3 4 -hd_keywords {file format} 4 +hd_keywords {first edition file format document} 5 5 source [file join $::DOC pages fancyformat.tcl] 6 6 fancyformat_document "SQLite Database File Format" hlr30000.txt { 7 7 8 8 [h1 "Document Overview"] 9 9 10 10 [h2 "Scope and Purpose"] 11 11 ................................................................................ 27 27 28 28 <li><p> To facilitate the development of external (non-SQLite) software that may 29 29 operate directly on SQLite databases stored within a file-system. For 30 30 example a database space analysis utility or a competing database 31 31 client implementation. 32 32 </ul> 33 33 34 + <p> 35 + A shorter and more recent \[second edition file format document\] 36 + also available. The two file format descriptions are independently 37 + written and hence serve as cross-checks of one another. Any 38 + incompatibilities between the two documents should be considered a bug. 39 + 34 40 <p> 35 41 The availability of this information makes an SQLite database an even safer 36 42 choice for long-term data storage. If at some point in the future the 37 43 SQLite software library cannot be used to access an SQLite database that 38 44 contains useful data, a procedure or software module may be developed based 39 45 on the content of this document to extract the required data. 40 46 ................................................................................ 630 636 is unlocked, another process may use SQLite to modify the 631 637 contents of the file, invalidating the internal cache of the 632 638 first process. When the file is relocked, the first process can 633 639 check if the value of the file change counter has been modified 634 640 since the file was unlocked. If it has not, then the internal 635 641 cache may be assumed to be valid and may be reused. 636 642 <td>H33040 643 + 644 + [Tr]<td>28..31 <td>4<td> 645 + <p style="margin-top:0"> 646 + The in-header database size. This field holds the logical size 647 + of the database file in pages. This field is only valid if it 648 + is nonzero and if the file change counter at offset 24 exactly 649 + matches the version-valid-for at offset 92. The in-header database 650 + size will only be valid when the database was last written by 651 + SQLite version 3.7.0 or later. If the in-header database size 652 + is valid, then it is used as the logical size of the database. 653 + If the in-header database size is not valid, then the actual 654 + database file size is examined to determine the logical database 655 + size. 656 + <td> 637 657 638 658 [Tr]<td>32..35 <td>4<td> 639 659 Page number of first freelist trunk page. 640 660 For more details, refer to section <cite>free_page_list</cite>. 641 661 <td>H31320 642 662 643 663 [Tr]<td>36..39 <td>4<td> ................................................................................ 714 734 so that it contains no free pages (section 715 735 <cite>free_page_list</cite>) at the end of each database 716 736 transaction. If incremental vacuum mode is enabled, then the 717 737 reorganization is not performed until explicitly requested 718 738 by the user. 719 739 <td>H30171 720 740 741 + [Tr]<td>92..95 <td>4<td> 742 + The version-valid-for integer. This is a copy of the 743 + file change counter (offset 24) for when the SQLite version number 744 + in offset 96 was written. This integer is also used to determine 745 + if the in-header database size (offset 28) is valid. 746 + <td> 747 + 748 + [Tr]<td>99..99 <td>4<td> 749 + The SQLite version number (obtained from \[SQLITE_VERSION_NUMBER\]) 750 + for the instance of SQLite that last wrote to the database file. 751 + Only SQLite versions 3.7.0 and later will update this number. 752 + <td> 753 + 721 754 </table> 722 755 723 756 <p> 724 757 The four byte block beginning at offset 28 stores a big-endian integer 725 758 which is the number of pages in the database. Older versions of 726 759 SQLite set this integer to zero. For compatibility, SQLite database 727 760 readers should be able to deal with either value. 728 761 </p> 729 762 730 763 <p> 731 - The 32 byte block beginning at offset 68 is currently unused. 732 - This might change in a future release of SQLite. 764 + The 32 byte block beginning at offset 68 is unused in SQLite versions 765 + up to and including 3.6.23.1. The 8 bytes at offset 92 came into use 766 + beginning with SQLite version 3.7.0. The 24 bytes between offset 68 767 + and offset 91 might come into use in a future release of SQLite. 733 768 </p> 734 769 735 770 <p> 736 771 The following requirements state that certain database header 737 772 fields must contain defined constant values, even though the sqlite 738 773 database file format is designed to allow various values. These fields 739 774 were intended to be flexible when the SQLite database image format
Changes to pages/fileformat2.in.
1 1 <title>File Format For SQLite Databases</title> 2 -<tcl>hd_keywords {file format redux}</tcl> 2 +<tcl>hd_keywords {file format} {second edition file format document}</tcl> 3 3 4 4 <h1 align=center> 5 5 The SQLite Database File Format 6 6 </h1> 7 7 8 8 <p>This document describes and defines the on-disk database file 9 9 format used by SQLite.</p> 10 10 11 11 <p>This is the second document to define the SQLite database file format. 12 -The [file format| first document] differs from this one in that it is 12 +The [first edition file format document] differs from this one in that it is 13 13 written in a formal style whereas this document attempts to be more 14 14 conversational. The two documents were independently written (they have 15 15 different authors) and hence serve as cross-checks for one another. 16 16 Both documents should describe exactly the same file format. 17 -Any discrepencies between the two documents should be considered a bug.</p> 17 +Any incompatibilities between the two documents should be considered a bug.</p> 18 18 19 19 <h2>1.0 The Database File</h2> 20 20 21 21 <p>Most of the time the complete state of an SQLite database 22 22 is contained a single file on disk called the "main database file".</p> 23 23 24 24 <p>While performing a transaction, SQLite stores some temporary information