SQLite

    const int isMemdb = (zFilename && strcmp(zFilename, ":memory:")==0)
                         || (isTempDb && sqlite3TempInMemory(db));
  #endif
#endif

  assert( db!=0 );
  assert( sqlite3_mutex_held(db->mutex) );
  assert( (flags&0xff)==flags );   /* flags fit in 8 bits */

  /* Only a BTREE_SINGLE database can be BTREE_UNORDERED */
  assert( (flags & BTREE_UNORDERED)==0 || (flags & BTREE_SINGLE)!=0 );

  /* A BTREE_SINGLE database is always a temporary and/or ephemeral */
  assert( (flags & BTREE_SINGLE)==0 || isTempDb );

  if( db->flags & SQLITE_NoReadlock ){
    flags |= BTREE_NO_READLOCK;
  }
  if( isMemdb ){
    flags |= BTREE_MEMORY;
  }

                          EXTRA_SIZE, flags, vfsFlags, pageReinit);
    if( rc==SQLITE_OK ){
      rc = sqlite3PagerReadFileheader(pBt->pPager,sizeof(zDbHeader),zDbHeader);
    }
    if( rc!=SQLITE_OK ){
      goto btree_open_out;
    }
    pBt->openFlags = flags;
    pBt->db = db;
    sqlite3PagerSetBusyhandler(pBt->pPager, btreeInvokeBusyHandler, pBt);
    p->pBt = pBt;
  
    pBt->pCursor = 0;
    pBt->pPage1 = 0;
    pBt->readOnly = sqlite3PagerIsreadonly(pBt->pPager);

** The type of type is determined by the flags parameter.  Only the
** following values of flags are currently in use.  Other values for
** flags might not work:
**
**     BTREE_INTKEY|BTREE_LEAFDATA     Used for SQL tables with rowid keys
**     BTREE_ZERODATA                  Used for SQL indices
*/
static int btreeCreateTable(Btree *p, int *piTable, int createTabFlags){
  BtShared *pBt = p->pBt;
  MemPage *pRoot;
  Pgno pgnoRoot;
  int rc;
  int ptfFlags;          /* Page-type flage for the root page of new table */

  assert( sqlite3BtreeHoldsMutex(p) );
  assert( pBt->inTransaction==TRANS_WRITE );
  assert( !pBt->readOnly );

#ifdef SQLITE_OMIT_AUTOVACUUM
  rc = allocateBtreePage(pBt, &pRoot, &pgnoRoot, 1, 0);

  }else{
    rc = allocateBtreePage(pBt, &pRoot, &pgnoRoot, 1, 0);
    if( rc ) return rc;
  }
#endif
  assert( sqlite3PagerIswriteable(pRoot->pDbPage) );
  if( createTabFlags & BTREE_INTKEY ){
    ptfFlags = PTF_INTKEY | PTF_LEAFDATA | PTF_LEAF;
  }else{
    ptfFlags = PTF_ZERODATA | PTF_LEAF;
  }
  zeroPage(pRoot, ptfFlags);
  sqlite3PagerUnref(pRoot->pDbPage);
  assert( (pBt->openFlags & BTREE_SINGLE)==0 || pgnoRoot==2 );
  *piTable = (int)pgnoRoot;
  return SQLITE_OK;
}
int sqlite3BtreeCreateTable(Btree *p, int *piTable, int flags){
  int rc;
  sqlite3BtreeEnter(p);
  rc = btreeCreateTable(p, piTable, flags);

/* 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_NO_READLOCK   2  /* Omit readlocks on readonly files */
#define BTREE_MEMORY        4  /* This is an in-memory DB */
#define BTREE_SINGLE        8  /* The file contains at most 1 b-tree */
#define BTREE_UNORDERED    16  /* Use of a hash implementation is OK */


int sqlite3BtreeClose(Btree*);
int sqlite3BtreeSetCacheSize(Btree*,int);
int sqlite3BtreeSetSafetyLevel(Btree*,int,int);
int sqlite3BtreeSyncDisabled(Btree*);
int sqlite3BtreeSetPageSize(Btree *p, int nPagesize, int nReserve, int eFix);
int sqlite3BtreeGetPageSize(Btree*);

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

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 */


int sqlite3BtreeDropTable(Btree*, int, int*);
int sqlite3BtreeClearTable(Btree*, int, int*);
void sqlite3BtreeTripAllCursors(Btree*, int);

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

  sqlite3 *db;          /* Database connection currently using this Btree */
  BtCursor *pCursor;    /* A list of all open cursors */
  MemPage *pPage1;      /* First page of the database */
  u8 readOnly;          /* True if the underlying file is readonly */
  u8 pageSizeFixed;     /* True if the page size can no longer be changed */
  u8 secureDelete;      /* True if secure_delete is enabled */
  u8 initiallyEmpty;    /* Database is empty at start of transaction */
  u8 openFlags;         /* Flags to sqlite3BtreeOpen() */
#ifndef SQLITE_OMIT_AUTOVACUUM
  u8 autoVacuum;        /* True if auto-vacuum is enabled */
  u8 incrVacuum;        /* True if incr-vacuum is enabled */
#endif
  u16 maxLocal;         /* Maximum local payload in non-LEAFDATA tables */
  u16 minLocal;         /* Minimum local payload in non-LEAFDATA tables */
  u16 maxLeaf;          /* Maximum local payload in a LEAFDATA table */

    pX->iTable = iTab;
  }
  return eType;
}
#endif

/*
** Generate code for scalar subqueries used as a subquery expression, EXISTS,
** or IN operators.  Examples:
**
**     (SELECT a FROM b)          -- subquery
**     EXISTS (SELECT a FROM b)   -- EXISTS subquery
**     x IN (4,5,11)              -- IN operator with list on right-hand side
**     x IN (SELECT a FROM b)     -- IN operator with subquery on the right
**
** The pExpr parameter describes the expression that contains the IN

    sqlite3VdbeAddOp1(v, OP_If, mem);
    testAddr = sqlite3VdbeAddOp2(v, OP_Integer, 1, mem);
    assert( testAddr>0 || pParse->db->mallocFailed );
  }

  switch( pExpr->op ){
    case TK_IN: {
      char affinity;              /* Affinity of the LHS of the IN */
      KeyInfo keyInfo;            /* Keyinfo for the generated table */
      int addr;                   /* Address of OP_OpenEphemeral instruction */
      Expr *pLeft = pExpr->pLeft; /* the LHS of the IN operator */

      if( rMayHaveNull ){
        sqlite3VdbeAddOp2(v, OP_Null, 0, rMayHaveNull);
      }

      affinity = sqlite3ExprAffinity(pLeft);

      ** SELECT... statement are columns, then numeric affinity is used
      ** if either column has NUMERIC or INTEGER affinity. If neither
      ** 'x' nor the SELECT... statement are columns, then numeric affinity
      ** is used.
      */
      pExpr->iTable = pParse->nTab++;
      addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, pExpr->iTable, !isRowid);
      if( rMayHaveNull==0 ) sqlite3VdbeChangeP5(v, BTREE_UNORDERED);
      memset(&keyInfo, 0, sizeof(keyInfo));
      keyInfo.nField = 1;

      if( ExprHasProperty(pExpr, EP_xIsSelect) ){
        /* Case 1:     expr IN (SELECT ...)
        **
        ** Generate code to write the results of the select into the temporary

  assert( v!=0 );  /* The VDBE already created by calling function */

  /* Create the destination temporary table if necessary
  */
  if( dest.eDest==SRT_EphemTab ){
    assert( p->pEList );
    sqlite3VdbeAddOp2(v, OP_OpenEphemeral, dest.iParm, p->pEList->nExpr);
    sqlite3VdbeChangeP5(v, BTREE_UNORDERED);
    dest.eDest = SRT_Table;
  }

  /* Make sure all SELECTs in the statement have the same number of elements
  ** in their result sets.
  */
  assert( p->pEList && pPrior->pEList );

  if( isDistinct ){
    KeyInfo *pKeyInfo;
    assert( isAgg || pGroupBy );
    distinct = pParse->nTab++;
    pKeyInfo = keyInfoFromExprList(pParse, p->pEList);
    sqlite3VdbeAddOp4(v, OP_OpenEphemeral, distinct, 0, 0,
                        (char*)pKeyInfo, P4_KEYINFO_HANDOFF);
    sqlite3VdbeChangeP5(v, BTREE_UNORDERED);
  }else{
    distinct = -1;
  }

  /* Aggregate and non-aggregate queries are handled differently */
  if( !isAgg && pGroupBy==0 ){
    /* This case is for non-aggregate queries

  
  /* Create the ephemeral table into which the update results will
  ** be stored.
  */
  assert( v );
  ephemTab = pParse->nTab++;
  sqlite3VdbeAddOp2(v, OP_OpenEphemeral, ephemTab, pTab->nCol+1+(pRowid!=0));
  sqlite3VdbeChangeP5(v, BTREE_UNORDERED);

  /* fill the ephemeral table 
  */
  sqlite3SelectDestInit(&dest, SRT_Table, ephemTab);
  sqlite3Select(pParse, pSelect, &dest);

  /* Generate code to scan the ephemeral table and call VUpdate. */

  }else if( pOp->p4type==P4_INT32 ){
    nField = pOp->p4.i;
  }
  assert( pOp->p1>=0 );
  pCur = allocateCursor(p, pOp->p1, nField, iDb, 1);
  if( pCur==0 ) goto no_mem;
  pCur->nullRow = 1;
  pCur->isOrdered = 1;
  rc = sqlite3BtreeCursor(pX, p2, wrFlag, pKeyInfo, pCur->pCursor);
  pCur->pKeyInfo = pKeyInfo;

  /* Since it performs no memory allocation or IO, the only values that
  ** sqlite3BtreeCursor() may return are SQLITE_EMPTY and SQLITE_OK. 
  ** SQLITE_EMPTY is only returned when attempting to open the table
  ** rooted at page 1 of a zero-byte database.  */

** different name to distinguish its use.  Tables created using
** by this opcode will be used for automatically created transient
** indices in joins.
*/
case OP_OpenAutoindex: 
case OP_OpenEphemeral: {
  VdbeCursor *pCx;
  static const int vfsFlags = 
      SQLITE_OPEN_READWRITE |
      SQLITE_OPEN_CREATE |
      SQLITE_OPEN_EXCLUSIVE |
      SQLITE_OPEN_DELETEONCLOSE |
      SQLITE_OPEN_TRANSIENT_DB;

  assert( pOp->p1>=0 );
  pCx = allocateCursor(p, pOp->p1, pOp->p2, -1, 1);
  if( pCx==0 ) goto no_mem;
  pCx->nullRow = 1;
  rc = sqlite3BtreeOpen(0, db, &pCx->pBt, 
                        BTREE_OMIT_JOURNAL | BTREE_SINGLE | pOp->p5, vfsFlags);
  if( rc==SQLITE_OK ){
    rc = sqlite3BtreeBeginTrans(pCx->pBt, 1);
  }
  if( rc==SQLITE_OK ){
    /* If a transient index is required, create it by calling
    ** sqlite3BtreeCreateTable() with the BTREE_BLOBKEY flag before
    ** opening it. If a transient table is required, just use the
    ** automatically created table with root-page 1 (an BLOB_INTKEY table).
    */
    if( pOp->p4.pKeyInfo ){
      int pgno;
      assert( pOp->p4type==P4_KEYINFO );
      rc = sqlite3BtreeCreateTable(pCx->pBt, &pgno, BTREE_BLOBKEY); 
      if( rc==SQLITE_OK ){
        assert( pgno==MASTER_ROOT+1 );
        rc = sqlite3BtreeCursor(pCx->pBt, pgno, 1, 
                                (KeyInfo*)pOp->p4.z, pCx->pCursor);
        pCx->pKeyInfo = pOp->p4.pKeyInfo;
        pCx->pKeyInfo->enc = ENC(p->db);
      }
      pCx->isTable = 0;
    }else{
      rc = sqlite3BtreeCursor(pCx->pBt, MASTER_ROOT, 1, 0, pCx->pCursor);
      pCx->isTable = 1;
    }
  }
  pCx->isOrdered = (pOp->p5!=BTREE_UNORDERED);
  pCx->isIndex = !pCx->isTable;
  break;
}

/* Opcode: OpenPseudo P1 P2 P3 * *
**
** Open a new cursor that points to a fake table that contains a single

  assert( pOp->p2!=0 );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  assert( pC->pseudoTableReg==0 );
  assert( OP_SeekLe == OP_SeekLt+1 );
  assert( OP_SeekGe == OP_SeekLt+2 );
  assert( OP_SeekGt == OP_SeekLt+3 );
  assert( pC->isOrdered );
  if( pC->pCursor!=0 ){
    oc = pOp->opcode;
    pC->nullRow = 0;
    if( pC->isTable ){
      /* The input value in P3 might be of any type: integer, real, string,
      ** blob, or NULL.  But it needs to be an integer before we can do
      ** the seek, so covert it. */

  VdbeCursor *pC;
  int res;
  UnpackedRecord r;

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  assert( pC->isOrdered );
  if( ALWAYS(pC->pCursor!=0) ){
    assert( pC->deferredMoveto==0 );
    assert( pOp->p5==0 || pOp->p5==1 );
    assert( pOp->p4type==P4_INT32 );
    r.pKeyInfo = pC->pKeyInfo;
    r.nField = (u16)pOp->p4.i;
    if( pOp->p5 ){

  pgno = 0;
  assert( pOp->p1>=0 && pOp->p1<db->nDb );
  assert( (p->btreeMask & (1<<pOp->p1))!=0 );
  pDb = &db->aDb[pOp->p1];
  assert( pDb->pBt!=0 );
  if( pOp->opcode==OP_CreateTable ){
    /* flags = BTREE_INTKEY; */
    flags = BTREE_INTKEY;
  }else{
    flags = BTREE_BLOBKEY;
  }
  rc = sqlite3BtreeCreateTable(pDb->pBt, &pgno, flags);
  pOut->u.i = pgno;
  break;
}

/* Opcode: ParseSchema P1 P2 * P4 *

  Bool rowidIsValid;    /* True if lastRowid is valid */
  Bool atFirst;         /* True if pointing to first entry */
  Bool useRandomRowid;  /* Generate new record numbers semi-randomly */
  Bool nullRow;         /* True if pointing to a row with no data */
  Bool deferredMoveto;  /* A call to sqlite3BtreeMoveto() is needed */
  Bool isTable;         /* True if a table requiring integer keys */
  Bool isIndex;         /* True if an index containing keys only - no data */
  Bool isOrdered;       /* True if the underlying table is BTREE_UNORDERED */
  i64 movetoTarget;     /* Argument to the deferred sqlite3BtreeMoveto() */
  Btree *pBt;           /* Separate file holding temporary table */
  int pseudoTableReg;   /* Register holding pseudotable content. */
  KeyInfo *pKeyInfo;    /* Info about index keys needed by index cursors */
  int nField;           /* Number of fields in the header */
  i64 seqCount;         /* Sequence counter */
  sqlite3_vtab_cursor *pVtabCursor;  /* The cursor for a virtual table */