Documentation Source Text: Check-in [2b4a307362]

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Overview

Comment:	Progress on btreemodule.html.
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SHA1:	2b4a307362b604ae9b8f4050679ed4fc11c43114
User & Date:	dan 2009-06-06 12:06:11.000

Context

2009-06-07
00:01		Add a rough draft of the document describing how to use fossil to maintain a private branch of SQLite. (check-in: ce4ee2b8d3 user: drh tags: trunk)
2009-06-06
12:06		Progress on btreemodule.html. (check-in: 2b4a307362 user: dan tags: trunk)
2009-06-02
19:19		Fix a typo on the Documents page. (check-in: ee05430080 user: drh tags: trunk)

Changes

Added images/btreemodule_balance_shallower.svg.

Changes to images/fileformat/rtdocs.css.

Changes to pages/btreemodule.in.

Changes to pages/fancyformat.tcl.

Changes to pages/fileformat.in.

Changes to req/hlr50000.txt.

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	<title>SQLite B-Tree Module</title> <tcl> hd_keywords {btree design} source [file join $::DOC pages fancyformat.tcl] ~~set fd [open [file join $SRC src btr~~ee.h~~]] set btr~~ee_h~~ [read $fd] close $fd ~~proc btree_api_defn {args} {~~~~ foreach api $args { set re_head {\n[^\n]} ~~if { [string match BTREE $api] } {~~ set re_tail {[^A-Za-z][^\n]\n} } else { set re_tail {[^;A-Za-z][^;];} } ~~regexp $re_head$api$re_tail $::btr~~ee_h~~ api_defn~~ lappend ret [string trim $api_defn] } return "<pre class=api>[join $ret "\n"]</pre>" } fancyformat_document "SQLite B-Tree Module" hlr50000.txt { [h1 "Document Overview"] [h2 "Scope and Purpose"]	> \| \| \| \| < > > > \| \| > > > > > > >	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 41 42 43	<title>SQLite B-Tree Module</title> <tcl> hd_keywords {btree design} source [file join $::DOC pages fancyformat.tcl] foreach header {btree.h sqliteInt.h} { set fd [open [file join $SRC src $header]] set headers($header) [read $fd] close $fd } proc header_api_defn {header args} { foreach api $args { set re_head {\n[^\n]} if { [string match struct $api] } { set re_tail {[^\{]\};\n} } elseif { [string match BTREE $api] } { set re_tail {[^A-Za-z][^\n]\n} } else { set re_tail {[^;A-Za-z][^;];} } regexp $re_head$api$re_tail $::headers($header) api_defn lappend ret [string trim $api_defn] } return "<pre class=api>[join $ret "\n"]</pre>" } proc btree_api_defn {args} { eval header_api_defn btree.h $args } proc sqliteint_api_defn {args} { eval header_api_defn sqliteInt.h $args } fancyformat_document "SQLite B-Tree Module" hlr50000.txt { [h1 "Document Overview"] [h2 "Scope and Purpose"]
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141 142 143 144 145 146 147 148 149 150 151 152 153 154	[h2 "Functional Requirements"] <p> This section contains requirements describing the functionality required from the B-Tree module. [h3 "Opening and Closing Connections"] <p> The B-Tree module provides an interface to open new b-tree database connections. [fancyformat_import_requirement H50010] [fancyformat_import_requirement H50020]	> > >	151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167	[h2 "Functional Requirements"] <p> This section contains requirements describing the functionality required from the B-Tree module. <p class=todo> Figure out where integrity-check goes. [h3 "Opening and Closing Connections"] <p> The B-Tree module provides an interface to open new b-tree database connections. [fancyformat_import_requirement H50010] [fancyformat_import_requirement H50020]
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400 401 402 403 404 405 406 ~~407~~ 408 ~~409 410~~ 411 412 413 414 415 416 417	an error is returned to the user. <td>H50150, H50151, H50152 [Tr] <td>Cache size <td>The cache-size parameter may be set to any integer value. How it affects operation depends on the specific P-Cache implementation used by the page-cache. <span class=todo>Refer to details for the behaviour of the built-in default P-Cache.</span> ~~<td>~~ [Tr] <td>Safety level ~~~~<td>~~<span class=todo>~~This!~~</span> <td>~~ </table> [fancyformat_import_requirement H50138] [fancyformat_import_requirement H50139] [fancyformat_import_requirement H50140] <p class=todo>	\| > \| \|	413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431	an error is returned to the user. <td>H50150, H50151, H50152 [Tr] <td>Cache size <td>The cache-size parameter may be set to any integer value. How it affects operation depends on the specific P-Cache implementation used by the page-cache. <span class=todo>Refer to details for the behaviour of the built-in default P-Cache.</span> <td>H50153 [Tr] <td>Safety level <td>The safety-level parameter may be set to "none", "normal" or "full". <span class=todo> Where will the effect of this defined/required?</span> <td>H50154, H50155 </table> [fancyformat_import_requirement H50138] [fancyformat_import_requirement H50139] [fancyformat_import_requirement H50140] <p class=todo>
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434 435 436 437 438 439 440 441 442 443 444 445 446 447	[fancyformat_import_requirement H50148] [fancyformat_import_requirement H50149] [fancyformat_import_requirement H50150] [fancyformat_import_requirement H50151] [fancyformat_import_requirement H50152] <p class=todo> Interface to set the codec function (encryption). <p class=todo> The busy-handler. Where exactly does this come in? Transactions and savepoints section?	> > > > > > > > > > > > > > > >	448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477	[fancyformat_import_requirement H50148] [fancyformat_import_requirement H50149] [fancyformat_import_requirement H50150] [fancyformat_import_requirement H50151] [fancyformat_import_requirement H50152] [fancyformat_import_requirement H50153] <p> See section <cite>hlr_memory</cite> for a description of and requirements specifying how the value of the cache-size parameter affects the operation of a page-cache. <span class=todo>Check this reference is relevant after it is written. Refer to a specific requirement if possible too.</span> [fancyformat_import_requirement H50154] [fancyformat_import_requirement H50155] <p class=todo> Description of what the safety-level actually does. Or pointer to where a description and requirements can be found (transactions section?). <p class=todo> Interface to set the codec function (encryption). <p class=todo> The busy-handler. Where exactly does this come in? Transactions and savepoints section?
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484 485 486 487 488 489 490 ~~491~~ 492 493 494 495 496 497 498	<ul> <li> Callbacks for backup module. <li> Page read/write APIs for backup module. </ul> [h2 "Other Requirements"] ~~[h3 "Caching and Memory Management Requirements"]~~ <ul> <li> Memory allocation related features (pcache, scratch memory, other...). <li> Default pcache implementation (sqlite3_release_memory()). <li> Schema memory object allocation (destructor registration). </ul> [h3 "Fault Tolerance Requirements"]	\|	514 515 516 517 518 519 520 521 522 523 524 525 526 527 528	<ul> <li> Callbacks for backup module. <li> Page read/write APIs for backup module. </ul> [h2 "Other Requirements"] [h3 "Caching and Memory Management Requirements" hlr_memory] <ul> <li> Memory allocation related features (pcache, scratch memory, other...). <li> Default pcache implementation (sqlite3_release_memory()). <li> Schema memory object allocation (destructor registration). </ul> [h3 "Fault Tolerance Requirements"]
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546 547 548 549 550 551 552 553 554 555 556 557 558 559	SQLite sub-systems to open and close B-Tree database connections. [btree_api_defn Btree] <p> A B-Tree database connection is accessed by other SQLite sub-systems using an opaque handle, modelled in C code using the type "Btree*". [btree_api_defn sqlite3BtreeOpen] [fancyformat_import_requirement H51001] [fancyformat_import_requirement H51002] [fancyformat_import_requirement H51003]	> >	576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591	SQLite sub-systems to open and close B-Tree database connections. [btree_api_defn Btree] <p> A B-Tree database connection is accessed by other SQLite sub-systems using an opaque handle, modelled in C code using the type "Btree*". [h3 sqlite3BtreeOpen] [btree_api_defn sqlite3BtreeOpen] [fancyformat_import_requirement H51001] [fancyformat_import_requirement H51002] [fancyformat_import_requirement H51003]
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592 593 594 595 596 597 598 599 600 601 602 603 604 605	H50050. [fancyformat_import_requirement H51007] [fancyformat_import_requirement H51008] <p class=todo> Requirements explaining how the db parameter to sqlite3BtreeOpen is used. Must be there for something. [btree_api_defn sqlite3BtreeClose] [fancyformat_import_requirement H51009] <p> If a call to sqlite3BtreeClose is made with a value that is not a valid	> >	624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639	H50050. [fancyformat_import_requirement H51007] [fancyformat_import_requirement H51008] <p class=todo> Requirements explaining how the db parameter to sqlite3BtreeOpen is used. Must be there for something. [h3 sqlite3BtreeClose] [btree_api_defn sqlite3BtreeClose] [fancyformat_import_requirement H51009] <p> If a call to sqlite3BtreeClose is made with a value that is not a valid
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654 655 656 657 658 659 660 ~~661 662 663 664~~ 665 666 667 668 669 670 671 672 673 674 675 676 677 678 ~~679 680 681 682 683 684~~ 685 686 687 688 689 690 691 692 693 ~~694~~ 695 ~~696~~ 697 698 699 700 701 702 703 704 705 706 707	configured to use an in-memory journal file or no journal file at all (<span class=todo>ref requirements</span>). In these cases the buffer returned contains the full-path of the journal file that would be used if the connection were configured to use a journal file. [h2 "Mutex Functions"] ~~<pre ~~class=~~api>struct BtreeMutexArray { ~~int nMutex;~~ ~~Btree *aBtree\[SQLITE_MAX_ATTACHED+1\];~~ ~~};</pre>~~~~ [btree_api_defn sqlite3BtreeEnter sqlite3BtreeEnterAll sqlite3BtreeLeave sqlite3BtreeEnterCursor sqlite3BtreeLeaveCursor sqlite3BtreeLeaveAll sqlite3BtreeMutexArrayEnter sqlite3BtreeMutexArrayLeave sqlite3BtreeMutexArrayInsert] [h2 "Transaction and Savepoint API"] [btree_api_defn sqlite3BtreeBeginTrans sqlite3BtreeCommitPhaseOne sqlite3BtreeCommitPhaseTwo sqlite3BtreeCommit sqlite3BtreeRollback] [btree_api_defn sqlite3BtreeBeginStmt sqlite3BtreeSavepoint] [btree_api_defn sqlite3BtreeIsInTrans sqlite3BtreeIsInReadTrans sqlite3BtreeIsInBackup] [h2 "Reading and Traversing the Database Image"] ~~[btree_api_defn BtCursor]~~ ~~[btree_api_defn sqlite3BtreeCursor sqlite3BtreeCursorSize sqlite3BtreeCloseCursor sqlite3BtreeClearCursor]~~ ~~[btree_api_defn sqlite3BtreeMoveto sqlite3BtreeMovetoUnpacked]~~ <p class=todo> sqlite3BtreeMoveto is never called from outside of the b-tree layer. It could/should be removed from the API. <p class=todo> The "bias" argument to sqlite3BtreeMovetoUnpacked is only ever true when it is called from within sqlite3BtreeInsert. This argument could/should also be removed from the API, if only to make it simpler to describe. ~~[btree_api_defn sqlite3BtreeFirst sqlite3BtreeLast sqlite3BtreeNext ~~sqlite3BtreePrevious sqlite3BtreeEof]~~~~ ~~[btree_api_defn sqlite3BtreeKeySize sqlite3BtreeKey sqlite3BtreeKeyFetch ~~sqlite3BtreeDataFetch sqlite3BtreeDataSize sqlite3BtreeData]~~~~ [btree_api_defn sqlite3BtreeCount] [btree_api_defn sqlite3BtreeGetMeta] [h2 "Modifying the Database Image"] [btree_api_defn sqlite3BtreeCreateTable] [btree_api_defn BTREE_INTKEY BTREE_ZERODATA BTREE_LEAFDATA]	\| < < < < < < < < < > > > > > \| > \| > > > > > > > > > > > > > > > > > > > > > > > > > > > > >	688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767	configured to use an in-memory journal file or no journal file at all (<span class=todo>ref requirements</span>). In these cases the buffer returned contains the full-path of the journal file that would be used if the connection were configured to use a journal file. [h2 "Mutex Functions"] [btree_api_defn {typedef struct BtreeMutexArray} {struct BtreeMutexArray \{}] [btree_api_defn sqlite3BtreeEnter sqlite3BtreeEnterAll sqlite3BtreeLeave sqlite3BtreeEnterCursor sqlite3BtreeLeaveCursor sqlite3BtreeLeaveAll sqlite3BtreeMutexArrayEnter sqlite3BtreeMutexArrayLeave sqlite3BtreeMutexArrayInsert] [h2 "Transaction and Savepoint API"] [btree_api_defn sqlite3BtreeBeginTrans sqlite3BtreeCommitPhaseOne sqlite3BtreeCommitPhaseTwo sqlite3BtreeCommit sqlite3BtreeRollback] [btree_api_defn sqlite3BtreeBeginStmt sqlite3BtreeSavepoint] [btree_api_defn sqlite3BtreeIsInTrans sqlite3BtreeIsInReadTrans sqlite3BtreeIsInBackup] [h2 "Reading and Traversing the Database Image"] <p class=todo> sqlite3BtreeMoveto is never called from outside of the b-tree layer. It could/should be removed from the API. <p class=todo> The "bias" argument to sqlite3BtreeMovetoUnpacked is only ever true when it is called from within sqlite3BtreeInsert. This argument could/should also be removed from the API, if only to make it simpler to describe. [btree_api_defn BtCursor] [btree_api_defn sqlite3BtreeCursor sqlite3BtreeCursorSize] [btree_api_defn sqlite3BtreeCloseCursor sqlite3BtreeClearCursor] [btree_api_defn sqlite3BtreeFirst sqlite3BtreeLast sqlite3BtreeNext \ sqlite3BtreePrevious sqlite3BtreeEof] [btree_api_defn sqlite3BtreeKeySize sqlite3BtreeKey sqlite3BtreeKeyFetch \ sqlite3BtreeDataFetch sqlite3BtreeDataSize sqlite3BtreeData] [btree_api_defn sqlite3BtreeCount] [btree_api_defn sqlite3BtreeMovetoUnpacked] <p class=todo> Not clear how to deal with these. Define an external module to encapsulate these and define sorting order etc.? That's tricky as things are because the UnpackedRecord.flags field defines the "search mode" used by sqlite3BtreeMovetoUnpacked. [sqliteint_api_defn {typedef struct KeyInfo} {struct KeyInfo \{}] [sqliteint_api_defn {typedef struct UnpackedRecord} {struct UnpackedRecord \{}] [h3 sqlite3BtreeGetMeta] <p> The sqlite3BtreeGetMeta interface may be used to retrieve the current value of certain fields from the database image header. [btree_api_defn sqlite3BtreeGetMeta] [fancyformat_import_requirement H51015] [btree_api_defn BTREE_FREE_PAGE_COUNT BTREE_SCHEMA_VERSION BTREE_FILE_FORMAT \ BTREE_DEFAULT_CACHE_SIZE BTREE_LARGEST_ROOT_PAGE BTREE_TEXT_ENCODING \ BTREE_USER_VERSION BTREE_INCR_VACUUM] [fancyformat_import_requirement H51016] [h2 "Modifying the Database Image"] [btree_api_defn sqlite3BtreeCreateTable] [btree_api_defn BTREE_INTKEY BTREE_ZERODATA BTREE_LEAFDATA]
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767 768 769 770 771 772 773 774 775 776 777 778 779 780	[h2 "Database Image Traversal and Manipulation"] <p class=todo> This section should describe exactly how bits and bytes are shifted around when the database image is traversed and modified. i.e. how a cursor seek is implemented, how the b-tree balancing works, deleting an internal cell from an index b-tree etc. [h2 "Transactions and Savepoints"] <p class=todo> Requirements surrounding how transactions are made atomic and isolated. Also how savepoints are implemented. What happens to active cursors after a rollback or savepoint-rollback.	> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >	827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916	[h2 "Database Image Traversal and Manipulation"] <p class=todo> This section should describe exactly how bits and bytes are shifted around when the database image is traversed and modified. i.e. how a cursor seek is implemented, how the b-tree balancing works, deleting an internal cell from an index b-tree etc. [h3 "B-Tree Insert"] [h3 "B-Tree Delete"] [h3 "B-Tree Balancing Algorithm"] <ul> <li><p>The <b>balance deeper</b> sub-algorithm is used when the root page of a b-tree is overfull. It creates a new page and copies the entire contents of the overfull root page to it. The root page is then zeroed and the new page installed as its only child. The balancing algorithm is then run on the new child page (in case it is overfull). <li><p>The <b>balance shallower</b> sub-algorithm is used when the root page of a b-tree has only a single child page. If possible, the data from the child page is copied into the root-page and the child page discarded. <li><p>The <b>balance intkey append</b> sub-algorithm is used in a very specific, but common scenario. It is used only for table b-trees, when a new entry that has a key value greater than all existing keys in the b-tree is inserted and causes the right-most leaf page of the b-tree structure to become overfull. <li><p>The <b>balance siblings</b> sub-algorithm is run when a b-tree page that is not the root-page of its table is either overfull or underfull. </ul> [h4 "Balance Deeper"] <ol> <li> Allocate a new page (the child-page). <li> Copy page data from root-page to child-page (including overflow cells). <li> Fix pointer map entries associated with new child-page content. <li> Zero the root-page. <li> Set the right-child pointer of the root-page to point to the new child-page. <li> Set the pointer map entry for the new child page. <li> Execute the balance procedure on the new child page. </ol> [h4 "Balance Shallower"] <ol> <li> Copy page data from child-page to root-page. <li> Fix pointer map entries associated with new root-page content. <li> Move child-page to database image free-list. </ol> [Figure btreemodule_balance_shallower.svg figure_balance_shallower "Example Balance Shallower Transform"] [h4 "Balance Intkey Append"] <ol> <li> Allocate a new page (the new sibling-page). <li> Populate the new sibling page with the new b-tree entry. <li> Add a new divider cell to the parent. The divider cell contains a pointer to the page that is currently the right-child of the parent. The key in the new divider cell is a copy of the largest key in the page that is currently the right-child of the parent. <li> Set the right-child of the parent page to point to the new sibling page. <li> If the database is an auto-vacuum database, set the pointer map entry associated with the new sibling page. If the cell on the new sibling page contains a pointer to an overflow page, set the pointer map entry associated with the overflow page. </ol> [h4 "Balance Siblings"] [h3 "Page Allocation and Deallocation"] [h2 "Transactions and Savepoints"] <p class=todo> Requirements surrounding how transactions are made atomic and isolated. Also how savepoints are implemented. What happens to active cursors after a rollback or savepoint-rollback.
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1365 1366 1367 1368 1369 1370 1371 ~~1372~~ 1373 1374 1375 1376 1377 1378 1379	offset of the cell containing the smallest record on the page, according to the comparison function defined in section <cite>index_btree_compare_func</cite>. <p> As well as the block of unused space between the cell offset array and the cell content area, which may be any size, there may be small blocks of free space interspersed with the B-Tree cells within the cell ~~content area. These are classified into two classes, depending on their ~~size:~~~~ <ul> <li>Blocks of free-space consisting of 3 bytes or less are called <b>fragments</b>. The total number of bytes consumed by all fragments on a page is stored in the 1 byte unsigned integer at byte offset 7 of the page header. The total number of fragmented bytes on a single page is never greater than 255. <li>Blocks of free-space consisting of more than 3 bytes of contiguous	\| >	1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380	offset of the cell containing the smallest record on the page, according to the comparison function defined in section <cite>index_btree_compare_func</cite>. <p> As well as the block of unused space between the cell offset array and the cell content area, which may be any size, there may be small blocks of free space interspersed with the B-Tree cells within the cell content area. These are classified into two classes, depending on their size: <ul> <li>Blocks of free-space consisting of 3 bytes or less are called <b>fragments</b>. The total number of bytes consumed by all fragments on a page is stored in the 1 byte unsigned integer at byte offset 7 of the page header. The total number of fragmented bytes on a single page is never greater than 255. <li>Blocks of free-space consisting of more than 3 bytes of contiguous
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1387 1388 1389 1390 1391 1392 1393 ~~1394~~ 1395 1396 1397 1398 1399 1400 1401	unsigned integer. The first two bytes of the final block in the list are set to zero. The third and fourth bytes of each free block contain the total size of the free block in bytes, stored as a 2 byte big-endian unsigned integer. </ul> <p class=todo> ~~The list of free blocks is kept in order, sorted by offset. Right?~~ [fancyformat_import_requirement H30810] [fancyformat_import_requirement H30820] <p> The following requirements describe the <i>B-Tree page header</i> present at the start of both index and table B-Tree pages.	\| > >	1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404	unsigned integer. The first two bytes of the final block in the list are set to zero. The third and fourth bytes of each free block contain the total size of the free block in bytes, stored as a 2 byte big-endian unsigned integer. </ul> <p class=todo> The list of free blocks is kept in order, sorted by offset. Right? Later: True statement. SQLite function sqlite3BtreeInitPage() returns SQLITE_CORRUPT if they are not. [fancyformat_import_requirement H30810] [fancyformat_import_requirement H30820] <p> The following requirements describe the <i>B-Tree page header</i> present at the start of both index and table B-Tree pages.
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288 289 290 291 292 293 294 295 296 ~~297~~ 298 299 300 301 302 303 304	HLR H50152 If the database-image size limit parameter is set to a non-negative value, and the user executes a write operation that would otherwise require the journal file to be extended to a size greater than the configured value in bytes, then the operation shall fail and an error be returned to the user. ~~HLR H51001~~ If successful, a call to the sqlite3BtreeOpen function shall return SQLITE_OK and set the value of *ppBtree to contain a new B-Tree database connection handle. HLR H51002 If unsuccessful, a call to the sqlite3BtreeOpen function shall return an SQLite error code other than SQLITE_OK indicating the reason for the failure. The	> > > > > > > > > > > > > > \|	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	HLR H50152 If the database-image size limit parameter is set to a non-negative value, and the user executes a write operation that would otherwise require the journal file to be extended to a size greater than the configured value in bytes, then the operation shall fail and an error be returned to the user. HLR H50153 The B-Tree module shall provide an interface to set the value of the cache-size configuration parameter of a page-cache, given an open b-tree database connection to that page-cache. HLR H50154 The B-Tree module shall provide an interface allowing the application to set the safety-level of a page-cache to one of "off", "normal" or "full", given an open b-tree database connection to that page-cache. HLR H50155 The default value assigned to the safety-level configuration parameter of a page-cache shall be "full". HLR H51001 H50010 If successful, a call to the sqlite3BtreeOpen function shall return SQLITE_OK and set the value of *ppBtree to contain a new B-Tree database connection handle. HLR H51002 If unsuccessful, a call to the sqlite3BtreeOpen function shall return an SQLite error code other than SQLITE_OK indicating the reason for the failure. The
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378 379 380 381 382 383 384 385	HLR H51014 A call to the sqlite3BtreeGetJournalname function with a valid B-Tree database connection handle opened on a temporary database as the first argument shall return a pointer to a buffer to a nul-terminated string zero bytes in length (i.e. the first byte of the buffer shall be 0x00).	> > > > > > > > > > > >	392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411	HLR H51014 A call to the sqlite3BtreeGetJournalname function with a valid B-Tree database connection handle opened on a temporary database as the first argument shall return a pointer to a buffer to a nul-terminated string zero bytes in length (i.e. the first byte of the buffer shall be 0x00). HLR H51015 H50109 If successful, a call to the sqlite3BtreeGetMeta function shall set the value of pValue to the current value of the specified 32-bit unsigned integer in the database image database header and return SQLITE_OK. HLR H51016 H50109 The database header field read from the database image by a call to sqlite3BtreeGetMeta shall be the 32-bit unsigned integer header field stored at byte offset (36 + 4 idx) of the database header, where idx is the value of the second parameter passed to sqlite3BtreeGetMeta.