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Overview
Comment:Comment changes in btree.c. No changes to code. (CVS 1988)
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SHA1: b15abf984fa06ae968d92fa9533dab20dcebd323
User & Date: drh 2004-09-27 13:19:52.000
Context
2004-09-30
13:43
Allow functions to be created when there are outstanding VMs. (Ticket #926) Fix problems with sqlite3_errcode(). Add tests for sqlite3_errcode(). (CVS 1989) (check-in: d0f1dc5898 user: drh tags: trunk)
2004-09-27
13:19
Comment changes in btree.c. No changes to code. (CVS 1988) (check-in: b15abf984f user: drh tags: trunk)
12:20
Bug fix in btree.c in cases where usableSize!=pageSize. Ticket #925. (CVS 1987) (check-in: cb3e12372d user: drh tags: trunk)
Changes
Side-by-Side Diff Ignore Whitespace Patch
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/*
** 2004 April 6
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** $Id: btree.c,v 1.190 2004/09/27 12:20:52 drh Exp $
** $Id: btree.c,v 1.191 2004/09/27 13:19:52 drh Exp $
**
** This file implements a external (disk-based) database using BTrees.
** For a detailed discussion of BTrees, refer to
**
**     Donald E. Knuth, THE ART OF COMPUTER PROGRAMMING, Volume 3:
**     "Sorting And Searching", pages 473-480. Addison-Wesley
**     Publishing Company, Reading, Massachusetts.
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**      3       2      number of cells on this page
**      5       2      first byte of the cell content area
**      7       1      number of fragmented free bytes
**      8       4      Right child (the Ptr(N+1) value).  Omitted on leaves.
**
** The flags define the format of this btree page.  The leaf flag means that
** this page has no children.  The zerodata flag means that this page carries
** only keys and no data.  The intkey flag means that the key is a single
** variable length integer at the beginning of the payload.
** only keys and no data.  The intkey flag means that the key is a integer
** which is stored in the key size entry of the cell header rather than in
** the payload area.
**
** The cell pointer array begins on the first byte after the page header.
** The cell pointer array contains zero or more 2-byte numbers which are
** offsets from the beginning of the page to the cell content in the cell
** content area.  The cell pointers occur in sorted order.  The system strives
** to keep free space after the last cell pointer so that new cells can
** be easily added without have to defragment the page.
** be easily added without having to defragment the page.
**
** Cell content is stored at the very end of the page and grows toward the
** beginning of the page.
**
** Unused space within the cell content area is collected into a linked list of
** freeblocks.  Each freeblock is at least 4 bytes in size.  The byte offset
** to the first freeblock is given in the header.  Freeblocks occur in
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