SQLite

  }else{
    assert( pCur->skipNext==0 );
    *pDifferentRow = 0;
  }
  return SQLITE_OK;
}

#ifdef SQLITE_ENABLE_CURSOR_HINTS
/*
** Provide hints to the cursor.  The particular hint given (and the type
** and number of the varargs parameters) is determined by the eHintType
** parameter.  See the definitions of the BTREE_HINT_* macros for details.
**
** Hints are not (currently) used by the native SQLite implementation.
** This mechanism is provided for systems that substitute an alternative
** storage engine.
*/
void sqlite3BtreeCursorHint(BtCursor *pCur, int eHintType, ...){
  va_list ap;
  va_start(ap, eHintType);

  switch( eHintType ){

    case BTREE_HINT_FLAGS: {


      pCur->hints = va_arg(ap, unsigned int);
      assert( pCur->hints==BTREE_SEEK_EQ || pCur->hints==BTREE_BULKLOAD
                  || pCur->hints==0 );
      break;
    }
    case BTREE_HINT_RANGE: {
      (void)va_arg(ap, Expr*);
      (void)va_arg(ap, struct Mem*);
      /* Range expression not used in this implementation */
      break;
    }
  }
  va_end(ap);
}
#endif /* SQLITE_ENABLE_CURSOR_HINTS */

#ifndef SQLITE_OMIT_AUTOVACUUM
/*
** Given a page number of a regular database page, return the page
** number for the pointer-map page that contains the entry for the
** input page number.
**

#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.
**
** Note that cursor hints are not used by the canonical SQLite b-tree
** ayer.  Cursor hints are provided so that systems that substitute their
** on custom b-tree layer can have access to additional information that might
** boost performance.  Hints are only provided if SQLite is compiled with
** SQLITE_ENABLE_CURSOR_HINTS.  The hinting interface is undocumented
** (except for comments such as this) and is subject to change from one
** release of SQLite to the next.
**
** BTREE_HINT_FLAGS  (arguments: unsigned int)
**
**     Some combinatation of BTREE_BULKLOAD and BTREE_SEEK_EQ flags.  The
**     argument is a single unsigned integer which overwrites all prior
**     flag settings.
**
** BTREE_HINT_RANGE  (arguments: Expr*, Mem*)

**     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.





*/
#define BTREE_HINT_FLAGS 1       /* Set flags indicating cursor usage */
#define BTREE_HINT_RANGE 2       /* 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 */

#ifdef SQLITE_ENABLE_CURSOR_HINTS
void sqlite3BtreeCursorHint(BtCursor*, int, ...);
#endif

int sqlite3BtreeCursor(
  Btree*,                              /* BTree containing table to open */
  int 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 */
);
int sqlite3BtreeCursorSize(void);
void sqlite3BtreeCursorZero(BtCursor*);


int sqlite3BtreeCloseCursor(BtCursor*);
int sqlite3BtreeMovetoUnpacked(
  BtCursor*,
  UnpackedRecord *pUnKey,
  i64 intKey,
  int bias,

  ** and report database corruption if they were not, but this check has
  ** since moved into the btree layer.  */  
  pCur->isTable = pOp->p4type!=P4_KEYINFO;

open_cursor_set_hints:
  assert( OPFLAG_BULKCSR==BTREE_BULKLOAD );
  assert( OPFLAG_SEEKEQ==BTREE_SEEK_EQ );

#ifdef SQLITE_ENABLE_CURSOR_HINTS


  sqlite3BtreeCursorHint(pCur->pCursor, BTREE_HINT_FLAGS,
                         (pOp->p5 & (OPFLAG_BULKCSR|OPFLAG_SEEKEQ)));
#endif
  break;
}

/* Opcode: OpenEphemeral P1 P2 * P4 P5
** Synopsis: nColumn=P2
**
** Open a new cursor P1 to a transient table.