SQLITE_BTREE_H

sqlite3.c, 237436行 = 全部源文件，找东西比多文件查找方便多了:-)，字符串查找一点都不慢。

不要太害怕，SQLite说它的代码里有非常多是用来做数据完整性检查和测试的。但愿B树，虚数据库引擎之类的不是太长。

/*************************************************************************
** This header file defines the interface that the sqlite B-Tree file
** subsystem.  See comments in the source code for a detailed description
** of what each interface routine does.
*/
#ifndef SQLITE_BTREE_H
#define SQLITE_BTREE_H

/* TODO: This definition is just included so other modules compile. It
** needs to be revisited.
*/
#define SQLITE_N_BTREE_META 16

/*
** If defined as non-zero, auto-vacuum is enabled by default. Otherwise
** it must be turned on for each database using "PRAGMA auto_vacuum = 1".
*/
#ifndef SQLITE_DEFAULT_AUTOVACUUM
  #define SQLITE_DEFAULT_AUTOVACUUM 0
#endif

#define BTREE_AUTOVACUUM_NONE 0        /* Do not do auto-vacuum */
#define BTREE_AUTOVACUUM_FULL 1        /* Do full auto-vacuum */
#define BTREE_AUTOVACUUM_INCR 2        /* Incremental vacuum */

/*
** Forward declarations of structure
*/
typedef struct Btree Btree;
typedef struct BtCursor BtCursor;
typedef struct BtShared BtShared;
typedef struct BtreePayload BtreePayload;


SQLITE_PRIVATE int sqlite3BtreeOpen(
  sqlite3_vfs *pVfs,       /* VFS to use with this b-tree */
  const char *zFilename,   /* Name of database file to open */
  sqlite3 *db,             /* Associated database connection */
  Btree **ppBtree,         /* Return open Btree* here */
  int flags,               /* Flags */
  int vfsFlags             /* Flags passed through to VFS open */
);

/* The flags parameter to sqlite3BtreeOpen can be the bitwise or of the
** following values.
**
** NOTE:  These values must match the corresponding PAGER_ values in
** pager.h.
*/
#define BTREE_OMIT_JOURNAL  1  /* Do not create or use a rollback journal */
#define BTREE_MEMORY        2  /* This is an in-memory DB */
#define BTREE_SINGLE        4  /* The file contains at most 1 b-tree */
#define BTREE_UNORDERED     8  /* Use of a hash implementation is OK */

SQLITE_PRIVATE int sqlite3BtreeClose(Btree*);
SQLITE_PRIVATE int sqlite3BtreeSetCacheSize(Btree*,int);
SQLITE_PRIVATE int sqlite3BtreeSetSpillSize(Btree*,int);
#if SQLITE_MAX_MMAP_SIZE>0
SQLITE_PRIVATE   int sqlite3BtreeSetMmapLimit(Btree*,sqlite3_int64);
#endif
SQLITE_PRIVATE int sqlite3BtreeSetPagerFlags(Btree*,unsigned);
SQLITE_PRIVATE int sqlite3BtreeSetPageSize(Btree *p, int nPagesize, int nReserve, int eFix);
SQLITE_PRIVATE int sqlite3BtreeGetPageSize(Btree*);
SQLITE_PRIVATE Pgno sqlite3BtreeMaxPageCount(Btree*,Pgno);
SQLITE_PRIVATE Pgno sqlite3BtreeLastPage(Btree*);
SQLITE_PRIVATE int sqlite3BtreeSecureDelete(Btree*,int);
SQLITE_PRIVATE int sqlite3BtreeGetRequestedReserve(Btree*);
SQLITE_PRIVATE int sqlite3BtreeGetReserveNoMutex(Btree *p);
SQLITE_PRIVATE int sqlite3BtreeSetAutoVacuum(Btree *, int);
SQLITE_PRIVATE int sqlite3BtreeGetAutoVacuum(Btree *);
SQLITE_PRIVATE int sqlite3BtreeBeginTrans(Btree*,int,int*);
SQLITE_PRIVATE int sqlite3BtreeCommitPhaseOne(Btree*, const char*);
SQLITE_PRIVATE int sqlite3BtreeCommitPhaseTwo(Btree*, int);
SQLITE_PRIVATE int sqlite3BtreeCommit(Btree*);
SQLITE_PRIVATE int sqlite3BtreeRollback(Btree*,int,int);
SQLITE_PRIVATE int sqlite3BtreeBeginStmt(Btree*,int);
SQLITE_PRIVATE int sqlite3BtreeCreateTable(Btree*, Pgno*, int flags);
SQLITE_PRIVATE int sqlite3BtreeTxnState(Btree*);
SQLITE_PRIVATE int sqlite3BtreeIsInBackup(Btree*);

SQLITE_PRIVATE void *sqlite3BtreeSchema(Btree *, int, void(*)(void *));
SQLITE_PRIVATE int sqlite3BtreeSchemaLocked(Btree *pBtree);
#ifndef SQLITE_OMIT_SHARED_CACHE
SQLITE_PRIVATE int sqlite3BtreeLockTable(Btree *pBtree, int iTab, u8 isWriteLock);
#endif

/* Savepoints are named, nestable SQL transactions mostly implemented */
/* in vdbe.c and pager.c See https://sqlite.org/lang_savepoint.html */
SQLITE_PRIVATE int sqlite3BtreeSavepoint(Btree *, int, int);

/* "Checkpoint" only refers to WAL. See https://sqlite.org/wal.html#ckpt */
#ifndef SQLITE_OMIT_WAL
SQLITE_PRIVATE   int sqlite3BtreeCheckpoint(Btree*, int, int *, int *);
#endif

SQLITE_PRIVATE const char *sqlite3BtreeGetFilename(Btree *);
SQLITE_PRIVATE const char *sqlite3BtreeGetJournalname(Btree *);
SQLITE_PRIVATE int sqlite3BtreeCopyFile(Btree *, Btree *);

SQLITE_PRIVATE int sqlite3BtreeIncrVacuum(Btree *);

/* The flags parameter to sqlite3BtreeCreateTable can be the bitwise OR
** of the flags shown below.
**
** Every SQLite table must have either BTREE_INTKEY or BTREE_BLOBKEY set.
** With BTREE_INTKEY, the table key is a 64-bit integer and arbitrary data
** is stored in the leaves.  (BTREE_INTKEY is used for SQL tables.)  With
** BTREE_BLOBKEY, the key is an arbitrary BLOB and no content is stored
** anywhere - the key is the content.  (BTREE_BLOBKEY is used for SQL
** indices.)
*/
#define BTREE_INTKEY     1    /* Table has only 64-bit signed integer keys */
#define BTREE_BLOBKEY    2    /* Table has keys only - no data */

SQLITE_PRIVATE int sqlite3BtreeDropTable(Btree*, int, int*);
SQLITE_PRIVATE int sqlite3BtreeClearTable(Btree*, int, i64*);
SQLITE_PRIVATE int sqlite3BtreeClearTableOfCursor(BtCursor*);
SQLITE_PRIVATE int sqlite3BtreeTripAllCursors(Btree*, int, int);

SQLITE_PRIVATE void sqlite3BtreeGetMeta(Btree *pBtree, int idx, u32 *pValue);
SQLITE_PRIVATE int sqlite3BtreeUpdateMeta(Btree*, int idx, u32 value);

SQLITE_PRIVATE int sqlite3BtreeNewDb(Btree *p);

/*
** The second parameter to sqlite3BtreeGetMeta or sqlite3BtreeUpdateMeta
** should be one of the following values. The integer values are assigned
** to constants so that the offset of the corresponding field in an
** SQLite database header may be found using the following formula:
**
**   offset = 36 + (idx * 4)
**
** For example, the free-page-count field is located at byte offset 36 of
** the database file header. The incr-vacuum-flag field is located at
** byte offset 64 (== 36+4*7).
**
** The BTREE_DATA_VERSION value is not really a value stored in the header.
** It is a read-only number computed by the pager.  But we merge it with
** the header value access routines since its access pattern is the same.
** Call it a "virtual meta value".
*/
#define BTREE_FREE_PAGE_COUNT     0
#define BTREE_SCHEMA_VERSION      1
#define BTREE_FILE_FORMAT         2
#define BTREE_DEFAULT_CACHE_SIZE  3
#define BTREE_LARGEST_ROOT_PAGE   4
#define BTREE_TEXT_ENCODING       5
#define BTREE_USER_VERSION        6
#define BTREE_INCR_VACUUM         7
#define BTREE_APPLICATION_ID      8
#define BTREE_DATA_VERSION        15  /* A virtual meta-value */

/*
** Kinds of hints that can be passed into the sqlite3BtreeCursorHint()
** interface.
**
** BTREE_HINT_RANGE  (arguments: Expr*, Mem*)
**
**     The first argument is an Expr* (which is guaranteed to be constant for
**     the lifetime of the cursor) that defines constraints on which rows
**     might be fetched with this cursor.  The Expr* tree may contain
**     TK_REGISTER nodes that refer to values stored in the array of registers
**     passed as the second parameter.  In other words, if Expr.op==TK_REGISTER
**     then the value of the node is the value in Mem[pExpr.iTable].  Any
**     TK_COLUMN node in the expression tree refers to the Expr.iColumn-th
**     column of the b-tree of the cursor.  The Expr tree will not contain
**     any function calls nor subqueries nor references to b-trees other than
**     the cursor being hinted.
**
**     The design of the _RANGE hint is aid b-tree implementations that try
**     to prefetch content from remote machines - to provide those
**     implementations with limits on what needs to be prefetched and thereby
**     reduce network bandwidth.
**
** Note that BTREE_HINT_FLAGS with BTREE_BULKLOAD is the only hint used by
** standard SQLite.  The other hints are provided for extentions that use
** the SQLite parser and code generator but substitute their own storage
** engine.
*/
#define BTREE_HINT_RANGE 0       /* Range constraints on queries */

/*
** Values that may be OR'd together to form the argument to the
** BTREE_HINT_FLAGS hint for sqlite3BtreeCursorHint():
**
** The BTREE_BULKLOAD flag is set on index cursors when the index is going
** to be filled with content that is already in sorted order.
**
** The BTREE_SEEK_EQ flag is set on cursors that will get OP_SeekGE or
** OP_SeekLE opcodes for a range search, but where the range of entries
** selected will all have the same key.  In other words, the cursor will
** be used only for equality key searches.
**
*/
#define BTREE_BULKLOAD 0x00000001  /* Used to full index in sorted order */
#define BTREE_SEEK_EQ  0x00000002  /* EQ seeks only - no range seeks */

/*
** Flags passed as the third argument to sqlite3BtreeCursor().
**
** For read-only cursors the wrFlag argument is always zero. For read-write
** cursors it may be set to either (BTREE_WRCSR|BTREE_FORDELETE) or just
** (BTREE_WRCSR). If the BTREE_FORDELETE bit is set, then the cursor will
** only be used by SQLite for the following:
**
**   * to seek to and then delete specific entries, and/or
**
**   * to read values that will be used to create keys that other
**     BTREE_FORDELETE cursors will seek to and delete.
**
** The BTREE_FORDELETE flag is an optimization hint.  It is not used by
** by this, the native b-tree engine of SQLite, but it is available to
** alternative storage engines that might be substituted in place of this
** b-tree system.  For alternative storage engines in which a delete of
** the main table row automatically deletes corresponding index rows,
** the FORDELETE flag hint allows those alternative storage engines to
** skip a lot of work.  Namely:  FORDELETE cursors may treat all SEEK
** and DELETE operations as no-ops, and any READ operation against a
** FORDELETE cursor may return a null row: 0x01 0x00.
*/
#define BTREE_WRCSR     0x00000004     /* read-write cursor */
#define BTREE_FORDELETE 0x00000008     /* Cursor is for seek/delete only */

SQLITE_PRIVATE int sqlite3BtreeCursor(
  Btree*,                              /* BTree containing table to open */
  Pgno iTable,                         /* Index of root page */
  int wrFlag,                          /* 1 for writing.  0 for read-only */
  struct KeyInfo*,                     /* First argument to compare function */
  BtCursor *pCursor                    /* Space to write cursor structure */
);
SQLITE_PRIVATE BtCursor *sqlite3BtreeFakeValidCursor(void);
SQLITE_PRIVATE int sqlite3BtreeCursorSize(void);
SQLITE_PRIVATE void sqlite3BtreeCursorZero(BtCursor*);
SQLITE_PRIVATE void sqlite3BtreeCursorHintFlags(BtCursor*, unsigned);
#ifdef SQLITE_ENABLE_CURSOR_HINTS
SQLITE_PRIVATE void sqlite3BtreeCursorHint(BtCursor*, int, ...);
#endif

SQLITE_PRIVATE int sqlite3BtreeCloseCursor(BtCursor*);
SQLITE_PRIVATE int sqlite3BtreeTableMoveto(
  BtCursor*,
  i64 intKey,
  int bias,
  int *pRes
);
SQLITE_PRIVATE int sqlite3BtreeIndexMoveto(
  BtCursor*,
  UnpackedRecord *pUnKey,
  int *pRes
);
SQLITE_PRIVATE int sqlite3BtreeCursorHasMoved(BtCursor*);
SQLITE_PRIVATE int sqlite3BtreeCursorRestore(BtCursor*, int*);
SQLITE_PRIVATE int sqlite3BtreeDelete(BtCursor*, u8 flags);

/* Allowed flags for sqlite3BtreeDelete() and sqlite3BtreeInsert() */
#define BTREE_SAVEPOSITION 0x02  /* Leave cursor pointing at NEXT or PREV */
#define BTREE_AUXDELETE    0x04  /* not the primary delete operation */
#define BTREE_APPEND       0x08  /* Insert is likely an append */
#define BTREE_PREFORMAT    0x80  /* Inserted data is a preformated cell */

/* An instance of the BtreePayload object describes the content of a single
** entry in either an index or table btree.
**
** Index btrees (used for indexes and also WITHOUT ROWID tables) contain
** an arbitrary key and no data.  These btrees have pKey,nKey set to the
** key and the pData,nData,nZero fields are uninitialized.  The aMem,nMem
** fields give an array of Mem objects that are a decomposition of the key.
** The nMem field might be zero, indicating that no decomposition is available.
**
** Table btrees (used for rowid tables) contain an integer rowid used as
** the key and passed in the nKey field.  The pKey field is zero.
** pData,nData hold the content of the new entry.  nZero extra zero bytes
** are appended to the end of the content when constructing the entry.
** The aMem,nMem fields are uninitialized for table btrees.
**
** Field usage summary:
**
**               Table BTrees                   Index Btrees
**
**   pKey        always NULL                    encoded key
**   nKey        the ROWID                      length of pKey
**   pData       data                           not used
**   aMem        not used                       decomposed key value
**   nMem        not used                       entries in aMem
**   nData       length of pData                not used
**   nZero       extra zeros after pData        not used
**
** This object is used to pass information into sqlite3BtreeInsert().  The
** same information used to be passed as five separate parameters.  But placing
** the information into this object helps to keep the interface more
** organized and understandable, and it also helps the resulting code to
** run a little faster by using fewer registers for parameter passing.
*/
struct BtreePayload {
  const void *pKey;       /* Key content for indexes.  NULL for tables */
  sqlite3_int64 nKey;     /* Size of pKey for indexes.  PRIMARY KEY for tabs */
  const void *pData;      /* Data for tables. */
  sqlite3_value *aMem;    /* First of nMem value in the unpacked pKey */
  u16 nMem;               /* Number of aMem[] value.  Might be zero */
  int nData;              /* Size of pData.  0 if none. */
  int nZero;              /* Extra zero data appended after pData,nData */
};

SQLITE_PRIVATE int sqlite3BtreeInsert(BtCursor*, const BtreePayload *pPayload,
                       int flags, int seekResult);
SQLITE_PRIVATE int sqlite3BtreeFirst(BtCursor*, int *pRes);
SQLITE_PRIVATE int sqlite3BtreeLast(BtCursor*, int *pRes);
SQLITE_PRIVATE int sqlite3BtreeNext(BtCursor*, int flags);
SQLITE_PRIVATE int sqlite3BtreeEof(BtCursor*);
SQLITE_PRIVATE int sqlite3BtreePrevious(BtCursor*, int flags);
SQLITE_PRIVATE i64 sqlite3BtreeIntegerKey(BtCursor*);
SQLITE_PRIVATE void sqlite3BtreeCursorPin(BtCursor*);
SQLITE_PRIVATE void sqlite3BtreeCursorUnpin(BtCursor*);
#ifdef SQLITE_ENABLE_OFFSET_SQL_FUNC
SQLITE_PRIVATE i64 sqlite3BtreeOffset(BtCursor*);
#endif
SQLITE_PRIVATE int sqlite3BtreePayload(BtCursor*, u32 offset, u32 amt, void*);
SQLITE_PRIVATE const void *sqlite3BtreePayloadFetch(BtCursor*, u32 *pAmt);
SQLITE_PRIVATE u32 sqlite3BtreePayloadSize(BtCursor*);
SQLITE_PRIVATE sqlite3_int64 sqlite3BtreeMaxRecordSize(BtCursor*);

SQLITE_PRIVATE char *sqlite3BtreeIntegrityCheck(sqlite3*,Btree*,Pgno*aRoot,int nRoot,int,int*);
SQLITE_PRIVATE struct Pager *sqlite3BtreePager(Btree*);
SQLITE_PRIVATE i64 sqlite3BtreeRowCountEst(BtCursor*);

#ifndef SQLITE_OMIT_INCRBLOB
SQLITE_PRIVATE int sqlite3BtreePayloadChecked(BtCursor*, u32 offset, u32 amt, void*);
SQLITE_PRIVATE int sqlite3BtreePutData(BtCursor*, u32 offset, u32 amt, void*);
SQLITE_PRIVATE void sqlite3BtreeIncrblobCursor(BtCursor *);
#endif
SQLITE_PRIVATE void sqlite3BtreeClearCursor(BtCursor *);
SQLITE_PRIVATE int sqlite3BtreeSetVersion(Btree *pBt, int iVersion);
SQLITE_PRIVATE int sqlite3BtreeCursorHasHint(BtCursor*, unsigned int mask);
SQLITE_PRIVATE int sqlite3BtreeIsReadonly(Btree *pBt);
SQLITE_PRIVATE int sqlite3HeaderSizeBtree(void);

#ifdef SQLITE_DEBUG
SQLITE_PRIVATE sqlite3_uint64 sqlite3BtreeSeekCount(Btree*);
#else
# define sqlite3BtreeSeekCount(X) 0
#endif

#ifndef NDEBUG
SQLITE_PRIVATE int sqlite3BtreeCursorIsValid(BtCursor*);
#endif
SQLITE_PRIVATE int sqlite3BtreeCursorIsValidNN(BtCursor*);

SQLITE_PRIVATE int sqlite3BtreeCount(sqlite3*, BtCursor*, i64*);

#ifdef SQLITE_TEST
SQLITE_PRIVATE int sqlite3BtreeCursorInfo(BtCursor*, int*, int);
SQLITE_PRIVATE void sqlite3BtreeCursorList(Btree*);
#endif

#ifndef SQLITE_OMIT_WAL
SQLITE_PRIVATE   int sqlite3BtreeCheckpoint(Btree*, int, int *, int *);
#endif

SQLITE_PRIVATE int sqlite3BtreeTransferRow(BtCursor*, BtCursor*, i64);

/*
** If we are not using shared cache, then there is no need to
** use mutexes to access the BtShared structures.  So make the
** Enter and Leave procedures no-ops.
*/
#ifndef SQLITE_OMIT_SHARED_CACHE
SQLITE_PRIVATE   void sqlite3BtreeEnter(Btree*);
SQLITE_PRIVATE   void sqlite3BtreeEnterAll(sqlite3*);
SQLITE_PRIVATE   int sqlite3BtreeSharable(Btree*);
SQLITE_PRIVATE   void sqlite3BtreeEnterCursor(BtCursor*);
SQLITE_PRIVATE   int sqlite3BtreeConnectionCount(Btree*);
#else
# define sqlite3BtreeEnter(X)
# define sqlite3BtreeEnterAll(X)
# define sqlite3BtreeSharable(X) 0
# define sqlite3BtreeEnterCursor(X)
# define sqlite3BtreeConnectionCount(X) 1
#endif

#if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE
SQLITE_PRIVATE   void sqlite3BtreeLeave(Btree*);
SQLITE_PRIVATE   void sqlite3BtreeLeaveCursor(BtCursor*);
SQLITE_PRIVATE   void sqlite3BtreeLeaveAll(sqlite3*);
#ifndef NDEBUG
  /* These routines are used inside assert() statements only. */
SQLITE_PRIVATE   int sqlite3BtreeHoldsMutex(Btree*);
SQLITE_PRIVATE   int sqlite3BtreeHoldsAllMutexes(sqlite3*);
SQLITE_PRIVATE   int sqlite3SchemaMutexHeld(sqlite3*,int,Schema*);
#endif
#else

# define sqlite3BtreeLeave(X)
# define sqlite3BtreeLeaveCursor(X)
# define sqlite3BtreeLeaveAll(X)

# define sqlite3BtreeHoldsMutex(X) 1
# define sqlite3BtreeHoldsAllMutexes(X) 1
# define sqlite3SchemaMutexHeld(X,Y,Z) 1
#endif


#endif /* SQLITE_BTREE_H */

 

/*
** This routine does a complete check of the given BTree file.  aRoot[] is
** an array of pages numbers were each page number is the root page of
** a table.  nRoot is the number of entries in aRoot.
**
** A read-only or read-write transaction must be opened before calling
** this function.
**
** Write the number of error seen in *pnErr.  Except for some memory
** allocation errors,  an error message held in memory obtained from
** malloc is returned if *pnErr is non-zero.  If *pnErr==0 then NULL is
** returned.  If a memory allocation error occurs, NULL is returned.
**
** If the first entry in aRoot[] is 0, that indicates that the list of
** root pages is incomplete.  This is a "partial integrity-check".  This
** happens when performing an integrity check on a single table.  The
** zero is skipped, of course.  But in addition, the freelist checks
** and the checks to make sure every page is referenced are also skipped,
** since obviously it is not possible to know which pages are covered by
** the unverified btrees.  Except, if aRoot[1] is 1, then the freelist
** checks are still performed.
*/
SQLITE_PRIVATE char *sqlite3BtreeIntegrityCheck(
  sqlite3 *db,  /* Database connection that is running the check */
  Btree *p,     /* The btree to be checked */
  Pgno *aRoot,  /* An array of root pages numbers for individual trees */
  int nRoot,    /* Number of entries in aRoot[] */
  int mxErr,    /* Stop reporting errors after this many */
  int *pnErr    /* Write number of errors seen to this variable */
){
  Pgno i;
  IntegrityCk sCheck;
  BtShared *pBt = p->pBt;
  u64 savedDbFlags = pBt->db->flags;
  char zErr[100];
  int bPartial = 0;            /* True if not checking all btrees */
  int bCkFreelist = 1;         /* True to scan the freelist */
  VVA_ONLY( int nRef );
  assert( nRoot>0 );

  /* aRoot[0]==0 means this is a partial check */
  if( aRoot[0]==0 ){
    assert( nRoot>1 );
    bPartial = 1;
    if( aRoot[1]!=1 ) bCkFreelist = 0;
  }

  sqlite3BtreeEnter(p);
  assert( p->inTrans>TRANS_NONE && pBt->inTransaction>TRANS_NONE );
  VVA_ONLY( nRef = sqlite3PagerRefcount(pBt->pPager) );
  assert( nRef>=0 );
  sCheck.db = db;
  sCheck.pBt = pBt;
  sCheck.pPager = pBt->pPager;
  sCheck.nPage = btreePagecount(sCheck.pBt);
  sCheck.mxErr = mxErr;
  sCheck.nErr = 0;
  sCheck.bOomFault = 0;
  sCheck.zPfx = 0;
  sCheck.v1 = 0;
  sCheck.v2 = 0;
  sCheck.aPgRef = 0;
  sCheck.heap = 0;
  sqlite3StrAccumInit(&sCheck.errMsg, 0, zErr, sizeof(zErr), SQLITE_MAX_LENGTH);
  sCheck.errMsg.printfFlags = SQLITE_PRINTF_INTERNAL;
  if( sCheck.nPage==0 ){
    goto integrity_ck_cleanup;
  }

  sCheck.aPgRef = sqlite3MallocZero((sCheck.nPage / 8)+ 1);
  if( !sCheck.aPgRef ){
    sCheck.bOomFault = 1;
    goto integrity_ck_cleanup;
  }
  sCheck.heap = (u32*)sqlite3PageMalloc( pBt->pageSize );
  if( sCheck.heap==0 ){
    sCheck.bOomFault = 1;
    goto integrity_ck_cleanup;
  }

  i = PENDING_BYTE_PAGE(pBt);
  if( i<=sCheck.nPage ) setPageReferenced(&sCheck, i);

  /* Check the integrity of the freelist
  */
  if( bCkFreelist ){
    sCheck.zPfx = "Main freelist: ";
    checkList(&sCheck, 1, get4byte(&pBt->pPage1->aData[32]),
              get4byte(&pBt->pPage1->aData[36]));
    sCheck.zPfx = 0;
  }

  /* Check all the tables.
  */
#ifndef SQLITE_OMIT_AUTOVACUUM
  if( !bPartial ){
    if( pBt->autoVacuum ){
      Pgno mx = 0;
      Pgno mxInHdr;
      for(i=0; (int)i<nRoot; i++) if( mx<aRoot[i] ) mx = aRoot[i];
      mxInHdr = get4byte(&pBt->pPage1->aData[52]);
      if( mx!=mxInHdr ){
        checkAppendMsg(&sCheck,
          "max rootpage (%d) disagrees with header (%d)",
          mx, mxInHdr
        );
      }
    }else if( get4byte(&pBt->pPage1->aData[64])!=0 ){
      checkAppendMsg(&sCheck,
        "incremental_vacuum enabled with a max rootpage of zero"
      );
    }
  }
#endif
  testcase( pBt->db->flags & SQLITE_CellSizeCk );
  pBt->db->flags &= ~(u64)SQLITE_CellSizeCk;
  for(i=0; (int)i<nRoot && sCheck.mxErr; i++){
    i64 notUsed;
    if( aRoot[i]==0 ) continue;
#ifndef SQLITE_OMIT_AUTOVACUUM
    if( pBt->autoVacuum && aRoot[i]>1 && !bPartial ){
      checkPtrmap(&sCheck, aRoot[i], PTRMAP_ROOTPAGE, 0);
    }
#endif
    checkTreePage(&sCheck, aRoot[i], &notUsed, LARGEST_INT64);
  }
  pBt->db->flags = savedDbFlags;

  /* Make sure every page in the file is referenced
  */
  if( !bPartial ){
    for(i=1; i<=sCheck.nPage && sCheck.mxErr; i++){
#ifdef SQLITE_OMIT_AUTOVACUUM
      if( getPageReferenced(&sCheck, i)==0 ){
        checkAppendMsg(&sCheck, "Page %d is never used", i);
      }
#else
      /* If the database supports auto-vacuum, make sure no tables contain
      ** references to pointer-map pages.
      */
      if( getPageReferenced(&sCheck, i)==0 &&
         (PTRMAP_PAGENO(pBt, i)!=i || !pBt->autoVacuum) ){
        checkAppendMsg(&sCheck, "Page %d is never used", i);
      }
      if( getPageReferenced(&sCheck, i)!=0 &&
         (PTRMAP_PAGENO(pBt, i)==i && pBt->autoVacuum) ){
        checkAppendMsg(&sCheck, "Pointer map page %d is referenced", i);
      }
#endif
    }
  }

  /* Clean  up and report errors.
  */
integrity_ck_cleanup:
  sqlite3PageFree(sCheck.heap);
  sqlite3_free(sCheck.aPgRef);
  if( sCheck.bOomFault ){
    sqlite3_str_reset(&sCheck.errMsg);
    sCheck.nErr++;
  }
  *pnErr = sCheck.nErr;
  if( sCheck.nErr==0 ) sqlite3_str_reset(&sCheck.errMsg);
  /* Make sure this analysis did not leave any unref() pages. */
  assert( nRef==sqlite3PagerRefcount(pBt->pPager) );
  sqlite3BtreeLeave(p);
  return sqlite3StrAccumFinish(&sCheck.errMsg);
}