** 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 1.41 2001/11/23 00:24:12 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.
................................................................................
  return rc;

page1_init_failed:
  sqlitepager_unref(pBt->page1);
  pBt->page1 = 0;
  return rc;
}



















/*
** Create a new database by initializing the first two pages of the
** file.
*/
static int newDatabase(Btree *pBt){
  MemPage *pRoot;
................................................................................
  if( pBt->inTrans ) return SQLITE_ERROR;
  if( pBt->page1==0 ){
    rc = lockBtree(pBt);
    if( rc!=SQLITE_OK ){
      return rc;
    }
  }
  if( !sqlitepager_isreadonly(pBt->pPager) ){


    rc = sqlitepager_write(pBt->page1);
    if( rc!=SQLITE_OK ){
      return rc;
    }
    rc = newDatabase(pBt);
  }

  pBt->inTrans = 1;
  return rc;
}

/*
** If there are no outstanding cursors and we are not in the middle
** of a transaction but there is a read lock on the database, then
** this routine unrefs the first page of the database file which 
** has the effect of releasing the read lock.
**
** If there are any outstanding cursors, this routine is a no-op.
**
** If there is a transaction in progress, this routine is a no-op.
*/
static void unlockBtreeIfUnused(Btree *pBt){
  if( pBt->inTrans==0 && pBt->pCursor==0 && pBt->page1!=0 ){
    sqlitepager_unref(pBt->page1);
    pBt->page1 = 0;
    pBt->inTrans = 0;
  }

}

/*
** Commit the transaction currently in progress.
**
** This will release the write lock on the database file.  If there
** are no active cursors, it also releases the read lock.
*/
int sqliteBtreeCommit(Btree *pBt){

** 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 1.42 2001/12/05 00:21:20 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.
................................................................................
  return rc;

page1_init_failed:
  sqlitepager_unref(pBt->page1);
  pBt->page1 = 0;
  return rc;
}

/*
** If there are no outstanding cursors and we are not in the middle
** of a transaction but there is a read lock on the database, then
** this routine unrefs the first page of the database file which 
** has the effect of releasing the read lock.
**
** If there are any outstanding cursors, this routine is a no-op.
**
** If there is a transaction in progress, this routine is a no-op.
*/
static void unlockBtreeIfUnused(Btree *pBt){
  if( pBt->inTrans==0 && pBt->pCursor==0 && pBt->page1!=0 ){
    sqlitepager_unref(pBt->page1);
    pBt->page1 = 0;
    pBt->inTrans = 0;
  }
}

/*
** Create a new database by initializing the first two pages of the
** file.
*/
static int newDatabase(Btree *pBt){
  MemPage *pRoot;
................................................................................
  if( pBt->inTrans ) return SQLITE_ERROR;
  if( pBt->page1==0 ){
    rc = lockBtree(pBt);
    if( rc!=SQLITE_OK ){
      return rc;
    }
  }
  if( sqlitepager_isreadonly(pBt->pPager) ){
    return SQLITE_READONLY;
  }
  rc = sqlitepager_write(pBt->page1);
  if( rc==SQLITE_OK ){


    rc = newDatabase(pBt);
  }
  if( rc==SQLITE_OK ){
    pBt->inTrans = 1;

  }else{











    unlockBtreeIfUnused(pBt);




  }
  return rc;
}

/*
** Commit the transaction currently in progress.
**
** This will release the write lock on the database file.  If there
** are no active cursors, it also releases the read lock.
*/
int sqliteBtreeCommit(Btree *pBt){

**     COPY
**     VACUUM
**     BEGIN TRANSACTION
**     COMMIT
**     ROLLBACK
**     PRAGMA
**
** $Id: build.c,v 1.57 2001/11/22 00:01:27 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** This routine is called after a single SQL statement has been
** parsed and we want to execute the VDBE code to implement 
................................................................................
** the schema to change multiple times and for the cookie to be
** set back to prior value.  But schema changes are infrequent
** and the probability of hitting the same cookie value is only
** 1 chance in 2^32.  So we're safe enough.
*/
static void changeCookie(sqlite *db){
  if( db->next_cookie==db->schema_cookie ){
    db->next_cookie = db->schema_cookie + sqliteRandomByte(db) + 1;
    db->flags |= SQLITE_InternChanges;
  }
}

/*
** This routine is called to report the final ")" that terminates
** a CREATE TABLE statement.

**     COPY
**     VACUUM
**     BEGIN TRANSACTION
**     COMMIT
**     ROLLBACK
**     PRAGMA
**
** $Id: build.c,v 1.58 2001/12/05 00:21:20 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** This routine is called after a single SQL statement has been
** parsed and we want to execute the VDBE code to implement 
................................................................................
** the schema to change multiple times and for the cookie to be
** set back to prior value.  But schema changes are infrequent
** and the probability of hitting the same cookie value is only
** 1 chance in 2^32.  So we're safe enough.
*/
static void changeCookie(sqlite *db){
  if( db->next_cookie==db->schema_cookie ){
    db->next_cookie = db->schema_cookie + sqliteRandomByte() + 1;
    db->flags |= SQLITE_InternChanges;
  }
}

/*
** This routine is called to report the final ")" that terminates
** a CREATE TABLE statement.

**
*************************************************************************
** Main file for the SQLite library.  The routines in this file
** implement the programmer interface to the library.  Routines in
** other files are for internal use by SQLite and should not be
** accessed by users of the library.
**
** $Id: main.c,v 1.50 2001/11/23 00:24:12 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"

/*
** This is the callback routine for the code that initializes the
** database.  See sqliteInit() below for additional information.
................................................................................

  /* Allocate the sqlite data structure */
  db = sqliteMalloc( sizeof(sqlite) );
  if( pzErrMsg ) *pzErrMsg = 0;
  if( db==0 ) goto no_mem_on_open;
  sqliteHashInit(&db->tblHash, SQLITE_HASH_STRING, 0);
  sqliteHashInit(&db->idxHash, SQLITE_HASH_STRING, 0);
  db->nextRowid = sqliteRandomInteger(db);
  
  /* Open the backend database driver */
  rc = sqliteBtreeOpen(zFilename, mode, MAX_PAGES, &db->pBe);
  if( rc!=SQLITE_OK ){
    switch( rc ){
      default: {
        if( pzErrMsg ){

**
*************************************************************************
** Main file for the SQLite library.  The routines in this file
** implement the programmer interface to the library.  Routines in
** other files are for internal use by SQLite and should not be
** accessed by users of the library.
**
** $Id: main.c,v 1.51 2001/12/05 00:21:20 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"

/*
** This is the callback routine for the code that initializes the
** database.  See sqliteInit() below for additional information.
................................................................................

  /* Allocate the sqlite data structure */
  db = sqliteMalloc( sizeof(sqlite) );
  if( pzErrMsg ) *pzErrMsg = 0;
  if( db==0 ) goto no_mem_on_open;
  sqliteHashInit(&db->tblHash, SQLITE_HASH_STRING, 0);
  sqliteHashInit(&db->idxHash, SQLITE_HASH_STRING, 0);
  db->nextRowid = sqliteRandomInteger();
  
  /* Open the backend database driver */
  rc = sqliteBtreeOpen(zFilename, mode, MAX_PAGES, &db->pBe);
  if( rc!=SQLITE_OK ){
    switch( rc ){
      default: {
        if( pzErrMsg ){

int sqliteOsSync(OsFile);
int sqliteOsTruncate(OsFile, int size);
int sqliteOsFileSize(OsFile, int *pSize);
int sqliteOsLock(OsFile, int wrlock);
int sqliteOsUnlock(OsFile);
int sqliteOsRandomSeed(char*);
int sqliteOsSleep(int ms);
void sqliteOsEnterMutex();
void sqliteOsLeaveMutex();



#endif /* _SQLITE_OS_H_ */

int sqliteOsSync(OsFile);
int sqliteOsTruncate(OsFile, int size);
int sqliteOsFileSize(OsFile, int *pSize);
int sqliteOsLock(OsFile, int wrlock);
int sqliteOsUnlock(OsFile);
int sqliteOsRandomSeed(char*);
int sqliteOsSleep(int ms);
void sqliteOsEnterMutex(void);
void sqliteOsLeaveMutex(void);



#endif /* _SQLITE_OS_H_ */

** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.31 2001/11/22 00:01:27 drh Exp $
*/
#include "sqliteInt.h"
#include "pager.h"
#include "os.h"
#include <assert.h>
#include <string.h>

................................................................................
      sqliteOsClose(pPager->jfd);
      sqliteOsDelete(pPager->zJournal);
      pPager->journalOpen = 0;
      return SQLITE_BUSY;
    }
    sqliteOsUnlock(pPager->fd);
    if( sqliteOsLock(pPager->fd, 1)!=SQLITE_OK ){


      sqliteFree(pPager->aInJournal);
      sqliteOsClose(pPager->jfd);
      sqliteOsDelete(pPager->zJournal);
      pPager->journalOpen = 0;

      pPager->state = SQLITE_UNLOCK;
      pPager->errMask |= PAGER_ERR_LOCK;
      return SQLITE_PROTOCOL;




    }
    pPager->state = SQLITE_WRITELOCK;
    sqlitepager_pagecount(pPager);
    pPager->origDbSize = pPager->dbSize;
    rc = sqliteOsWrite(pPager->jfd, aJournalMagic, sizeof(aJournalMagic));
    if( rc==SQLITE_OK ){
      rc = sqliteOsWrite(pPager->jfd, &pPager->dbSize, sizeof(Pgno));

** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.32 2001/12/05 00:21:20 drh Exp $
*/
#include "sqliteInt.h"
#include "pager.h"
#include "os.h"
#include <assert.h>
#include <string.h>

................................................................................
      sqliteOsClose(pPager->jfd);
      sqliteOsDelete(pPager->zJournal);
      pPager->journalOpen = 0;
      return SQLITE_BUSY;
    }
    sqliteOsUnlock(pPager->fd);
    if( sqliteOsLock(pPager->fd, 1)!=SQLITE_OK ){
      sqliteOsUnlock(pPager->fd);
      rc = sqliteOsLock(pPager->fd, 0);
      sqliteFree(pPager->aInJournal);
      sqliteOsClose(pPager->jfd);
      sqliteOsDelete(pPager->zJournal);
      pPager->journalOpen = 0;
      if( rc ){
        pPager->state = SQLITE_UNLOCK;
        pPager->errMask |= PAGER_ERR_LOCK;
        return SQLITE_PROTOCOL;
      }else{
        pPager->state = SQLITE_READLOCK;
        return SQLITE_BUSY;
      }
    }
    pPager->state = SQLITE_WRITELOCK;
    sqlitepager_pagecount(pPager);
    pPager->origDbSize = pPager->dbSize;
    rc = sqliteOsWrite(pPager->jfd, aJournalMagic, sizeof(aJournalMagic));
    if( rc==SQLITE_OK ){
      rc = sqliteOsWrite(pPager->jfd, &pPager->dbSize, sizeof(Pgno));

**    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.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.71 2001/11/22 00:01:27 drh Exp $
*/
#include "sqlite.h"
#include "hash.h"
#include "vdbe.h"
#include "parse.h"
#include "btree.h"
#include <stdio.h>
................................................................................
int sqliteExprCompare(Expr*, Expr*);
int sqliteFuncId(Token*);
int sqliteExprResolveIds(Parse*, IdList*, Expr*);
void sqliteExprResolveInSelect(Parse*, Expr*);
int sqliteExprAnalyzeAggregates(Parse*, Expr*);
void sqliteParseInfoReset(Parse*);
Vdbe *sqliteGetVdbe(Parse*);
int sqliteRandomByte();
int sqliteRandomInteger();
void sqliteBeginTransaction(Parse*);
void sqliteCommitTransaction(Parse*);
void sqliteRollbackTransaction(Parse*);
char *sqlite_mprintf(const char *, ...);

**    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.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.72 2001/12/05 00:21:20 drh Exp $
*/
#include "sqlite.h"
#include "hash.h"
#include "vdbe.h"
#include "parse.h"
#include "btree.h"
#include <stdio.h>
................................................................................
int sqliteExprCompare(Expr*, Expr*);
int sqliteFuncId(Token*);
int sqliteExprResolveIds(Parse*, IdList*, Expr*);
void sqliteExprResolveInSelect(Parse*, Expr*);
int sqliteExprAnalyzeAggregates(Parse*, Expr*);
void sqliteParseInfoReset(Parse*);
Vdbe *sqliteGetVdbe(Parse*);
int sqliteRandomByte(void);
int sqliteRandomInteger(void);
void sqliteBeginTransaction(Parse*);
void sqliteCommitTransaction(Parse*);
void sqliteRollbackTransaction(Parse*);
char *sqlite_mprintf(const char *, ...);

proc chng {date desc} {
  puts "<DT><B>$date</B></DT>"
  puts "<DD><P><UL>$desc</UL></P></DD>"
}

chng {2001 Nov ?? (2.1.4)} {




<li>Add the ability to put a single .command in the second argument
    of the sqlite shell</li>

}

chng {2001 Nov 23 (2.1.3)} {
<li>Fix the behavior of comparison operators 
    (ex: "<b>&lt</b>", "<b>==</b>", etc.)
    so that they are consistent with the order of entries in an index.</li>
<li>Correct handling of integers in SQL expressions that are larger than

proc chng {date desc} {
  puts "<DT><B>$date</B></DT>"
  puts "<DD><P><UL>$desc</UL></P></DD>"
}

chng {2001 Dec 4 (2.1.4)} {
<li>Sometime <b>sqlite_exec()</b> would return SQLITE_PROTOCOL when it
    should have returned SQLITE_BUSY.</li>
<li>The fix to the previous bug uncovered a deadlock which was also
    fixed.</li>
<li>Add the ability to put a single .command in the second argument
    of the sqlite shell</li>
<li>Updates to the FAQ</li>
}

chng {2001 Nov 23 (2.1.3)} {
<li>Fix the behavior of comparison operators 
    (ex: "<b>&lt</b>", "<b>==</b>", etc.)
    so that they are consistent with the order of entries in an index.</li>
<li>Correct handling of integers in SQL expressions that are larger than

#
# Run this script to generated a faq.html output file
#
set rcsid {$Id: faq.tcl,v 1.2 2001/11/24 13:23:05 drh Exp $}

puts {<html>
<head>
  <title>SQLite Frequently Asked Questions</title>
</head>
<body bgcolor="white">
<h1 align="center">Frequently Asked Questions</h1>
................................................................................

  <p>If only one string in a comparison is a pure numeric, then that string
  is assumed to be less than the other.  Of neither string is a pure numeric,
  then <b>strcmp()</b> is used for the comparison.</p>
}

faq {
  The second INSERT in the following sequence of commands returns with 
  constraint error.
  <blockquote>
     CREATE TABLE t(s varchar(10) primary key);<br>
     INSERT INTO t VALUES('0');<br>
     INSERT INTO t VALUES('0.0');<br>
  </blockquote>
  Why is this?
} {
  <p>Because column <b>s</b> is a primary key, all values of <b>s</b> must
  be unique.  But SQLite thinks that <b>'0'</b> and <b>'0.0'</b> are the
  same value because they compare equal to one another numerically.
  (See the previous question.)  Hence the values are not unique and the
  constraint fails.</p>

................................................................................
  </ol>
}
        
faq {
  My linux box is not able to read an SQLite database that was created
  on my SparcStation.
} {
  <p>The x86 processor on your windows box is little-endian (meaning that
  the least signification byte of integers comes first) but the Sparc is
  big-endian (the most significant bytes comes first).  SQLite databases
  created on a little-endian architecture cannot be used on a big-endian
  machine and vice versa.</p>

  <p>If you need to move the database from one machine to another, you'll
  have to do an ASCII dump of the database on the source machine and then
................................................................................
  <p>The SQLITE_MASTER table is read-only.  You cannot change this table
  using UPDATE, INSERT, or DELETE.  The table is automatically updated by
  CREATE TABLE, CREATE INDEX, DROP TABLE, and DROP INDEX commands.</p>

  <p>Temporary tables do not appear in the SQLITE_MASTER table.  At this time
  there is no way to get a listing of temporary tables and indices.</p>
}

























# End of questions and answers.
#############

puts {<DL COMPACT>}
for {set i 1} {$i<$cnt} {incr i} {
  puts "  <DT><A HREF=\"#q$i\">($i)</A></DT>"
  puts "  <DD>[lindex $faq($i) 0]</DD>"
}
puts {</DL><HR />}

for {set i 1} {$i<$cnt} {incr i} {
  puts "<A NAME=\"q$i\">"
  puts "<P><B>($i) [lindex $faq($i) 0]</B></P>\n"
  puts "<BLOCKQUOTE>[lindex $faq($i) 1]</BLOCKQUOTE>\n"
}

puts {

<p><hr /></p>
<p><a href="index.html"><img src="/goback.jpg" border=0 />
Back to the SQLite Home Page</a>
</p>

</body></html>}

#
# Run this script to generated a faq.html output file
#
set rcsid {$Id: faq.tcl,v 1.3 2001/12/05 00:21:21 drh Exp $}

puts {<html>
<head>
  <title>SQLite Frequently Asked Questions</title>
</head>
<body bgcolor="white">
<h1 align="center">Frequently Asked Questions</h1>
................................................................................

  <p>If only one string in a comparison is a pure numeric, then that string
  is assumed to be less than the other.  Of neither string is a pure numeric,
  then <b>strcmp()</b> is used for the comparison.</p>
}

faq {
  Why does the second INSERT in the following sequence of commands throw
  a constraint exception?
  <blockquote>
     CREATE TABLE t(s varchar(10) primary key);<br>
     INSERT INTO t VALUES('0');<br>
     INSERT INTO t VALUES('0.0');<br>
  </blockquote>

} {
  <p>Because column <b>s</b> is a primary key, all values of <b>s</b> must
  be unique.  But SQLite thinks that <b>'0'</b> and <b>'0.0'</b> are the
  same value because they compare equal to one another numerically.
  (See the previous question.)  Hence the values are not unique and the
  constraint fails.</p>

................................................................................
  </ol>
}
        
faq {
  My linux box is not able to read an SQLite database that was created
  on my SparcStation.
} {
  <p>The x86 processor on your linux box is little-endian (meaning that
  the least signification byte of integers comes first) but the Sparc is
  big-endian (the most significant bytes comes first).  SQLite databases
  created on a little-endian architecture cannot be used on a big-endian
  machine and vice versa.</p>

  <p>If you need to move the database from one machine to another, you'll
  have to do an ASCII dump of the database on the source machine and then
................................................................................
  <p>The SQLITE_MASTER table is read-only.  You cannot change this table
  using UPDATE, INSERT, or DELETE.  The table is automatically updated by
  CREATE TABLE, CREATE INDEX, DROP TABLE, and DROP INDEX commands.</p>

  <p>Temporary tables do not appear in the SQLITE_MASTER table.  At this time
  there is no way to get a listing of temporary tables and indices.</p>
}

faq {
  Is there any known size limits to SQLite databases.
} {
  <p>Internally, SQLite can handle databases up to 2^40 bytes (1 terabyte)
  in size.  But the backend interface to POSIX and Win32 limits files to
  2^31 (2 gigabytes).</p>

  <p>SQLite arbitrarily limits the amount of data in one row to 1 megabyte.
  There is a single #define in the source code that can be changed to raise
  this limit as high as 16 megabytes if desired.</p>

  <p>There is a theoretical limit of about 2^32 (4 billion) rows
  in a single table, but there
  is no way to test this limit without exceeding the maximum file size, so
  it is not really an issue.  There is also a theoretical limit of about 2^32
  tables and indices, but again it is not really possible to reach this
  limit due to the file size constraint.</p>

  <p>The name and "CREATE TABLE" statement for a table must fit entirely
  within a 1-megabyte row of the SQLITE_MASTER table.  Other than this,
  there are no constraints on the length of the name of a table, or on the
  number of columns, etc.  Indices are similarly unconstrained.</p>
}

# End of questions and answers.
#############

puts {<DL COMPACT>}
for {set i 1} {$i<$cnt} {incr i} {
  puts "  <DT><A HREF=\"#q$i\">($i)</A></DT>"
  puts "  <DD>[lindex $faq($i) 0]</DD>"
}
puts {</DL>}

for {set i 1} {$i<$cnt} {incr i} {
  puts "<A NAME=\"q$i\"><HR />"
  puts "<P><B>($i) [lindex $faq($i) 0]</B></P>\n"
  puts "<BLOCKQUOTE>[lindex $faq($i) 1]</BLOCKQUOTE></LI>\n"
}

puts {
</OL>
<p><hr /></p>
<p><a href="index.html"><img src="/goback.jpg" border=0 />
Back to the SQLite Home Page</a>
</p>

</body></html>}