SQLite

/*
** 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 1.369 2007/05/03 11:43:33 danielk1977 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.

    Pgno iGuess = ovfl+1;
    u8 eType;

    while( PTRMAP_ISPAGE(pBt, iGuess) || iGuess==PENDING_BYTE_PAGE(pBt) ){
      iGuess++;
    }

    if( iGuess<=sqlite3PagerPagecount(pBt->pPager) ){
      rc = ptrmapGet(pBt, iGuess, &eType, &pgno);
      if( rc!=SQLITE_OK ){
        return rc;
      }
      if( eType==PTRMAP_OVERFLOW2 && pgno==ovfl ){
        next = iGuess;
      }

#ifdef SQLITE_OMIT_AUTOVACUUM
  rc = allocateBtreePage(pBt, &pRoot, &pgnoRoot, 1, 0);
  if( rc ) return rc;
#else
  if( pBt->autoVacuum ){
    Pgno pgnoMove;      /* Move a page here to make room for the root-page */
    MemPage *pPageMove; /* The page to move to. */

#ifndef SQLITE_OMIT_INCRBLOB
    /* Creating a new table may probably require moving an existing database
    ** to make room for the new tables root page. In case this page turns
    ** out to be an overflow page, delete all overflow page-map caches
    ** held by open cursors.
    */
    BtCursor *pCur;
    for(pCur=pBt->pCursor; pCur; pCur=pCur->pNext){
      sqliteFree(pCur->aOverflow);
      pCur->aOverflow = 0;
    }
#endif

    /* Read the value of meta[3] from the database to determine where the
    ** root page of the new table should go. meta[3] is the largest root-page
    ** created so far, so the new root-page is (meta[3]+1).
    */
    rc = sqlite3BtreeGetMeta(p, 4, &pgnoRoot);
    if( rc!=SQLITE_OK ) return rc;

** INTKEY table currently pointing at a valid table entry. 
** This function modifies the data stored as part of that entry.
** Only the data content may only be modified, it is not possible
** to change the length of the data stored.
*/
int sqlite3BtreePutData(BtCursor *pCsr, u32 offset, u32 amt, const void *z){
  BtShared *pBt = pCsr->pBtree->pBt;












  /* Check some preconditions: 
  **   (a) a write-transaction is open, 
  **   (b) the cursor is open for writing,
  **   (c) there is no read-lock on the table being modified and
  **   (d) the cursor points at a valid row of an intKey table.
  */

/*
** 2007 May 1
**
** 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: vdbeblob.c,v 1.3 2007/05/03 11:43:33 danielk1977 Exp $
*/

#include "sqliteInt.h"
#include "vdbeInt.h"

#ifndef SQLITE_OMIT_INCRBLOB

  do {
    Parse sParse;
    Table *pTab;

    memset(&sParse, 0, sizeof(Parse));
    sParse.db = db;

    rc = sqlite3SafetyOn(db);
    if( rc!=SQLITE_OK ){
      return rc;
    }

    pTab = sqlite3LocateTable(&sParse, zTable, zDb);
    if( !pTab ){
      sqlite3Error(db, sParse.rc, "%s", sParse.zErrMsg);
      sqliteFree(sParse.zErrMsg);
      rc = sParse.rc;
      sqlite3SafetyOff(db);
      goto blob_open_out;
    }

    /* Now search pTab for the exact column. */
    for(iCol=0; iCol < pTab->nCol; iCol++) {
      if( sqlite3StrICmp(pTab->aCol[iCol].zName, zColumn)==0 ){
        break;
      }
    }
    if( iCol==pTab->nCol ){
      sqlite3Error(db, SQLITE_ERROR, "no such column: %s", zColumn);
      sqliteFree(sParse.zErrMsg);
      rc = SQLITE_ERROR;
      sqlite3SafetyOff(db);
      goto blob_open_out;
    }

    v = sqlite3VdbeCreate(db);
    if( v ){
      int iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
      sqlite3VdbeAddOpList(v, sizeof(openBlob)/sizeof(VdbeOpList), openBlob);

      ** always return an SQL NULL. This is useful because it means
      ** we can invoke OP_Column to fill in the vdbe cursors type 
      ** and offset cache without causing any IO.
      */
      sqlite3VdbeChangeP2(v, 5, pTab->nCol+1);
      sqlite3VdbeMakeReady(v, 1, 0, 1, 0);
    }

    rc = sqlite3SafetyOff(db);
    if( rc!=SQLITE_OK ){
      return rc;
    }

    sqlite3_bind_int64((sqlite3_stmt *)v, 1, iRow);
    rc = sqlite3_step((sqlite3_stmt *)v);
    if( rc!=SQLITE_ROW ){
      nAttempt++;
      rc = sqlite3_finalize((sqlite3_stmt *)v);
      v = 0;

# 2007 May 1
#
# 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: incrblob.test,v 1.3 2007/05/03 11:43:35 danielk1977 Exp $
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl

do_test incrblob-1.1 {
  execsql {
    CREATE TABLE blobs(k PRIMARY KEY, v BLOB);

do_test incrblob-1.2.6 {
  execsql {
    SELECT v FROM blobs WHERE rowid = 1;
  }
} {1234567890}

#--------------------------------------------------------------------
# Test cases incrblob-1.3.X check that it is possible to read and write
# regions of a blob that lie on overflow pages.
#
do_test incrblob-1.3.1 {
  set ::str "[string repeat . 10000]"
  execsql {
    INSERT INTO blobs(rowid, k, v) VALUES(3, 'three', $::str);
  }
} {}

do_test incrblob-1.3.2 {
  set ::blob [db incrblob blobs v 3]
  seek $::blob 8500
  read $::blob 10
} {..........}

do_test incrblob-1.3.3 {
  seek $::blob 8500
  puts -nonewline $::blob 1234567890
} {}

do_test incrblob-1.3.4 {
  seek $::blob 8496
  read $::blob 10
} {....123456}
do_test incrblob-1.3.10 {
  close $::blob
} {}


#------------------------------------------------------------------------
# incrblob-2.*: Test seeking in an incremental blob can use ptrmap pages.
#
proc nRead {db} {
  set bt [btree_from_db $db]
  array set stats [btree_pager_stats $bt]
  return $stats(read)
}

foreach AutoVacuumMode [list 0 1] {

  db close
  file delete -force test.db test.db-journal

  sqlite3 db test.db
  execsql "PRAGMA auto_vacuum = $AutoVacuumMode"

  do_test incrblob-2.$AutoVacuumMode.1 {
    set ::str [string repeat abcdefghij 2900]
    execsql {
      BEGIN;
      CREATE TABLE blobs(k PRIMARY KEY, v BLOB);
      DELETE FROM blobs;
      INSERT INTO blobs VALUES('one', $::str || randstr(500,500));
      COMMIT;
    }
    expr [file size test.db]/1024
  } [expr 31 + $AutoVacuumMode]

  do_test incrblob-2.$AutoVacuumMode.2 {
    execsql {
      PRAGMA auto_vacuum;
    }
  } $AutoVacuumMode

  do_test incrblob-2.$AutoVacuumMode.3 {
    # Open and close the db to make sure the page cache is empty.
    db close
    sqlite3 db test.db
  
    # Read the last 20 bytes of the blob via a blob handle.
    set ::blob [db incrblob blobs v 1]
    seek $::blob -20 end
    set ::fragment [read $::blob]
    close $::blob
  
    # If the database is not in auto-vacuum mode, the whole of
    # the overflow-chain must be scanned. In auto-vacuum mode,
    # sqlite uses the ptrmap pages to avoid reading the other pages.
    #
    nRead db
  } [expr $AutoVacuumMode ? 4 : 30]

  do_test incrblob-2.3 {
    string range [db one {SELECT v FROM blobs}] end-19 end
  } $::fragment
}

finish_test