SQLite

      { OP_Integer,     0, 2,        0},
      { OP_Subtract,    1, 2,        1},
      { OP_IfPos,       1, 8,        0},
      { OP_Integer,     0, 1,        0},                         /* 6 */
      { OP_Noop,        0, 0,        0},
      { OP_ResultRow,   1, 1,        0},
    };
    VdbeOp *aOp;
    sqlite3VdbeUsesBtree(v, iDb);
    if( !zRight ){
      setOneColumnName(v, "cache_size");
      pParse->nMem += 2;
      sqlite3VdbeVerifyAvailableSpace(v, ArraySize(getCacheSize));
      aOp = sqlite3VdbeAddOpList(v, ArraySize(getCacheSize), getCacheSize, iLn);
      assert( aOp!=0 );
      aOp[0].p1 = iDb;
      aOp[1].p1 = iDb;
      aOp[6].p1 = SQLITE_DEFAULT_CACHE_SIZE;
    }else{
      int size = sqlite3AbsInt32(sqlite3Atoi(zRight));
      sqlite3BeginWriteOperation(pParse, 0, iDb);
      sqlite3VdbeAddOp2(v, OP_Integer, size, 1);
      sqlite3VdbeAddOp3(v, OP_SetCookie, iDb, BTREE_DEFAULT_CACHE_SIZE, 1);
      assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
      pDb->pSchema->cache_size = size;

          { OP_Transaction,    0,         1,                 0},    /* 0 */
          { OP_ReadCookie,     0,         1,         BTREE_LARGEST_ROOT_PAGE},
          { OP_If,             1,         0,                 0},    /* 2 */
          { OP_Halt,           SQLITE_OK, OE_Abort,          0},    /* 3 */
          { OP_Integer,        0,         1,                 0},    /* 4 */
          { OP_SetCookie,      0,         BTREE_INCR_VACUUM, 1},    /* 5 */
        };
        VdbeOp *aOp;
        int iAddr = sqlite3VdbeCurrentAddr(v);
        sqlite3VdbeVerifyAvailableSpace(v, ArraySize(setMeta6));
        aOp = sqlite3VdbeAddOpList(v, ArraySize(setMeta6), setMeta6, iLn);
        assert( aOp!=0 );
        aOp[0].p1 = iDb;
        aOp[1].p1 = iDb;
        aOp[2].p2 = iAddr+4;
        aOp[4].p1 = eAuto - 1;
        aOp[5].p1 = iDb;
        sqlite3VdbeUsesBtree(v, iDb);
      }
    }
    break;
  }
#endif

  /* Pragma "quick_check" is reduced version of 
  ** integrity_check designed to detect most database corruption
  ** without most of the overhead of a full integrity-check.
  */
  case PragTyp_INTEGRITY_CHECK: {
    int i, j, addr, mxErr;













    int isQuick = (sqlite3Tolower(zLeft[0])=='q');

    /* If the PRAGMA command was of the form "PRAGMA <db>.integrity_check",
    ** then iDb is set to the index of the database identified by <db>.
    ** In this case, the integrity of database iDb only is verified by
    ** the VDBE created below.
    **

          sqlite3VdbeLoadString(v, 3, pIdx->zName);
          sqlite3VdbeAddOp3(v, OP_Concat, 3, 2, 7);
          sqlite3VdbeAddOp2(v, OP_ResultRow, 7, 1);
        }
#endif /* SQLITE_OMIT_BTREECOUNT */
      } 
    }
    {
      static const int iLn = VDBE_OFFSET_LINENO(2);
      static const VdbeOpList endCode[] = {
        { OP_AddImm,      1, 0,        0},    /* 0 */
        { OP_If,          1, 0,        0},    /* 1 */
        { OP_String8,     0, 3,        0},    /* 2 */
        { OP_ResultRow,   3, 1,        0},
      };
      VdbeOp *aOp;

      aOp = sqlite3VdbeAddOpList(v, ArraySize(endCode), endCode, iLn);
      if( aOp ){
        aOp[0].p2 = -mxErr;
        aOp[1].p2 = sqlite3VdbeCurrentAddr(v);
        aOp[2].p4type = P4_STATIC;
        aOp[2].p4.z = "ok";
      }
    }
  }
  break;
#endif /* SQLITE_OMIT_INTEGRITY_CHECK */

#ifndef SQLITE_OMIT_UTF16
  /*
  **   PRAGMA encoding

    if( zRight && (pPragma->mPragFlag & PragFlag_ReadOnly)==0 ){
      /* Write the specified cookie value */
      static const VdbeOpList setCookie[] = {
        { OP_Transaction,    0,  1,  0},    /* 0 */
        { OP_Integer,        0,  1,  0},    /* 1 */
        { OP_SetCookie,      0,  0,  1},    /* 2 */
      };
      VdbeOp *aOp;
      sqlite3VdbeVerifyAvailableSpace(v, ArraySize(setCookie));
      aOp = sqlite3VdbeAddOpList(v, ArraySize(setCookie), setCookie, 0);
      assert( aOp!=0 );
      aOp[0].p1 = iDb;
      aOp[1].p1 = sqlite3Atoi(zRight);
      aOp[2].p1 = iDb;
      aOp[2].p2 = iCookie;
    }else{
      /* Read the specified cookie value */
      static const VdbeOpList readCookie[] = {
        { OP_Transaction,     0,  0,  0},    /* 0 */
        { OP_ReadCookie,      0,  1,  0},    /* 1 */
        { OP_ResultRow,       1,  1,  0}
      };
      VdbeOp *aOp;
      sqlite3VdbeVerifyAvailableSpace(v, ArraySize(readCookie));
      aOp = sqlite3VdbeAddOpList(v, ArraySize(readCookie),readCookie,0);
      assert( aOp!=0 );
      aOp[0].p1 = iDb;
      aOp[1].p1 = iDb;
      aOp[1].p3 = iCookie;
      sqlite3VdbeSetNumCols(v, 1);
      sqlite3VdbeSetColName(v, 0, COLNAME_NAME, zLeft, SQLITE_TRANSIENT);
    }
  }
  break;
#endif /* SQLITE_OMIT_SCHEMA_VERSION_PRAGMAS */

int sqlite3VdbeGoto(Vdbe*,int);
int sqlite3VdbeLoadString(Vdbe*,int,const char*);
void sqlite3VdbeMultiLoad(Vdbe*,int,const char*,...);
int sqlite3VdbeAddOp3(Vdbe*,int,int,int,int);
int sqlite3VdbeAddOp4(Vdbe*,int,int,int,int,const char *zP4,int);
int sqlite3VdbeAddOp4Dup8(Vdbe*,int,int,int,int,const u8*,int);
int sqlite3VdbeAddOp4Int(Vdbe*,int,int,int,int,int);
#ifdef SQLITE_DEBUG
  void sqlite3VdbeVerifyAvailableSpace(Vdbe *p, int N);
#else
# define sqlite3VdbeVerifyAvailableSpace(A,B)
#endif
VdbeOp *sqlite3VdbeAddOpList(Vdbe*, int nOp, VdbeOpList const *aOp, int iLineno);
void sqlite3VdbeAddParseSchemaOp(Vdbe*,int,char*);
void sqlite3VdbeChangeOpcode(Vdbe*, u32 addr, u8);
void sqlite3VdbeChangeP1(Vdbe*, u32 addr, int P1);
void sqlite3VdbeChangeP2(Vdbe*, u32 addr, int P2);
void sqlite3VdbeChangeP3(Vdbe*, u32 addr, int P3);
void sqlite3VdbeChangeP5(Vdbe*, u8 P5);
void sqlite3VdbeJumpHere(Vdbe*, int addr);
int sqlite3VdbeChangeToNoop(Vdbe*, int addr);
int sqlite3VdbeDeletePriorOpcode(Vdbe*, u8 op);
void sqlite3VdbeChangeP4(Vdbe*, int addr, const char *zP4, int N);
void sqlite3VdbeSetP4KeyInfo(Parse*, Index*);
void sqlite3VdbeUsesBtree(Vdbe*, int);
VdbeOp *sqlite3VdbeGetOp(Vdbe*, int);
int sqlite3VdbeMakeLabel(Vdbe*);
void sqlite3VdbeRunOnlyOnce(Vdbe*);

  va_list ap;
  int i;
  char c;
  va_start(ap, zTypes);
  for(i=0; (c = zTypes[i])!=0; i++){
    if( c=='s' ){
      const char *z = va_arg(ap, const char*);
      sqlite3VdbeAddOp4(p, z==0 ? OP_Null : OP_String8, 0, iDest++, 0, z, 0);

    }else{
      assert( c=='i' );
      sqlite3VdbeAddOp2(p, OP_Integer, va_arg(ap, int), iDest++);
    }
  }
  va_end(ap);
}

** Return the address of the next instruction to be inserted.
*/
int sqlite3VdbeCurrentAddr(Vdbe *p){
  assert( p->magic==VDBE_MAGIC_INIT );
  return p->nOp;
}

/*
** Verify that at least N opcode slots are available in p without
** having to malloc for more space.  This interface is used for
** testing only.
*/
#ifdef SQLITE_DEBUG
void sqlite3VdbeVerifyAvailableSpace(Vdbe *p, int N){
  assert( p->nOp + N <= p->pParse->nOpAlloc );
}
#endif

/*
** This function returns a pointer to the array of opcodes associated with
** the Vdbe passed as the first argument. It is the callers responsibility
** to arrange for the returned array to be eventually freed using the 
** vdbeFreeOpArray() function.
**
** Before returning, *pnOp is set to the number of entries in the returned

  resolveP2Values(p, pnMaxArg);
  *pnOp = p->nOp;
  p->aOp = 0;
  return aOp;
}

/*
** Add a whole list of operations to the operation stack.  Return a
** pointer to the first operation inserted.
*/
VdbeOp *sqlite3VdbeAddOpList(
  Vdbe *p,                     /* Add opcodes to the prepared statement */
  int nOp,                     /* Number of opcodes to add */
  VdbeOpList const *aOp,       /* The opcodes to be added */
  int iLineno                  /* Source-file line number of first opcode */
){
  int i;
  VdbeOp *pOut, *pFirst;
  assert( nOp>0 );
  assert( p->magic==VDBE_MAGIC_INIT );
  if( p->nOp + nOp > p->pParse->nOpAlloc && growOpArray(p, nOp) ){
    return 0;
  }

  pFirst = pOut = &p->aOp[p->nOp];
  for(i=0; i<nOp; i++, aOp++, pOut++){
    pOut->opcode = aOp->opcode;
    pOut->p1 = aOp->p1;
    pOut->p2 = aOp->p2;
    assert( aOp->p2>=0 );
    pOut->p3 = aOp->p3;
    pOut->p4type = P4_NOTUSED;
    pOut->p4.p = 0;
    pOut->p5 = 0;
#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
    pOut->zComment = 0;
#endif
#ifdef SQLITE_VDBE_COVERAGE
    pOut->iSrcLine = iLineno+i;
#else
    (void)iLineno;
#endif
#ifdef SQLITE_DEBUG
    if( p->db->flags & SQLITE_VdbeAddopTrace ){
      sqlite3VdbePrintOp(0, i+p->nOp, &p->aOp[i+p->nOp]);
    }
#endif
  }
  p->nOp += nOp;
  return pFirst;
}

#if defined(SQLITE_ENABLE_STMT_SCANSTATUS)
/*
** Add an entry to the array of counters managed by sqlite3_stmt_scanstatus().
*/
void sqlite3VdbeScanStatus(

  p->pNext = pVdbe->pProgram;
  pVdbe->pProgram = p;
}

/*
** Change the opcode at addr into OP_Noop
*/
int sqlite3VdbeChangeToNoop(Vdbe *p, int addr){
  VdbeOp *pOp;
  if( p->db->mallocFailed ) return 0;
  assert( addr>=0 && addr<p->nOp );
  pOp = &p->aOp[addr];

  freeP4(p->db, pOp->p4type, pOp->p4.p);
  memset(pOp, 0, sizeof(pOp[0]));
  pOp->opcode = OP_Noop;

  return 1;
}

/*
** If the last opcode is "op" and it is not a jump destination,
** then remove it.  Return true if and only if an opcode was removed.
*/
int sqlite3VdbeDeletePriorOpcode(Vdbe *p, u8 op){
  if( (p->nOp-1)>(p->pParse->iFixedOp) && p->aOp[p->nOp-1].opcode==op ){
    return sqlite3VdbeChangeToNoop(p, p->nOp-1);

  }else{
    return 0;
  }
}

/*
** Change the value of the P4 operand for a specific instruction.

  const char *zColumn,    /* The column containing the blob */
  sqlite_int64 iRow,      /* The row containing the glob */
  int flags,              /* True -> read/write access, false -> read-only */
  sqlite3_blob **ppBlob   /* Handle for accessing the blob returned here */
){
  int nAttempt = 0;
  int iCol;               /* Index of zColumn in row-record */
































  int rc = SQLITE_OK;
  char *zErr = 0;
  Table *pTab;
  Parse *pParse = 0;
  Incrblob *pBlob = 0;

#ifdef SQLITE_ENABLE_API_ARMOR

        goto blob_open_out;
      }
    }

    pBlob->pStmt = (sqlite3_stmt *)sqlite3VdbeCreate(pParse);
    assert( pBlob->pStmt || db->mallocFailed );
    if( pBlob->pStmt ){
      
      /* This VDBE program seeks a btree cursor to the identified 
      ** db/table/row entry. The reason for using a vdbe program instead
      ** of writing code to use the b-tree layer directly is that the
      ** vdbe program will take advantage of the various transaction,
      ** locking and error handling infrastructure built into the vdbe.
      **
      ** After seeking the cursor, the vdbe executes an OP_ResultRow.
      ** Code external to the Vdbe then "borrows" the b-tree cursor and
      ** uses it to implement the blob_read(), blob_write() and 
      ** blob_bytes() functions.
      **
      ** The sqlite3_blob_close() function finalizes the vdbe program,
      ** which closes the b-tree cursor and (possibly) commits the 
      ** transaction.
      */
      static const int iLn = VDBE_OFFSET_LINENO(3);
      static const VdbeOpList openBlob[] = {
        /* {OP_Transaction, 0, 0, 0},  // inserted separately */
        {OP_TableLock, 0, 0, 0},       /* 0: Acquire a read or write lock */
        {OP_OpenRead, 0, 0, 0},        /* 1: Open cursor 0 for reading */
        {OP_OpenWrite, 0, 0, 0},       /* 2: Open cursor 0 for read/write */
        {OP_Variable, 1, 1, 1},        /* 3: Push the rowid to the stack */
        {OP_NotExists, 0, 10, 1},      /* 4: Seek the cursor */
        {OP_Column, 0, 0, 1},          /* 5  */
        {OP_ResultRow, 1, 0, 0},       /* 6  */
        {OP_Goto, 0, 4, 0},            /* 7  */
        {OP_Close, 0, 0, 0},           /* 8  */
        {OP_Halt, 0, 0, 0},            /* 9 */
      };
      Vdbe *v = (Vdbe *)pBlob->pStmt;
      int iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
      VdbeOp *aOp;

      sqlite3VdbeAddOp4Int(v, OP_Transaction, iDb, flags, 
                           pTab->pSchema->schema_cookie,
                           pTab->pSchema->iGeneration);
      sqlite3VdbeChangeP5(v, 1);     
      aOp = sqlite3VdbeAddOpList(v, ArraySize(openBlob), openBlob, iLn);

      /* Make sure a mutex is held on the table to be accessed */
      sqlite3VdbeUsesBtree(v, iDb); 

      if( db->mallocFailed==0 ){
        assert( aOp!=0 );
        /* Configure the OP_TableLock instruction */
#ifdef SQLITE_OMIT_SHARED_CACHE
        aOp[0].opcode = OP_Noop;
#else
        aOp[0].p1 = iDb;
        aOp[0].p2 = pTab->tnum;
        aOp[0].p3 = flags;
        sqlite3VdbeChangeP4(v, 1, pTab->zName, P4_TRANSIENT);
      }
      if( db->mallocFailed==0 ){
#endif

        /* Remove either the OP_OpenWrite or OpenRead. Set the P2 
        ** parameter of the other to pTab->tnum.  */
        aOp[2-flags].opcode = OP_Noop;
        aOp[1+flags].p2 = pTab->tnum;
        aOp[1+flags].p3 = iDb;   

        /* Configure the number of columns. Configure the cursor to
        ** think that the table has one more column than it really
        ** does. An OP_Column to retrieve this imaginary column will
        ** 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.
        */
        aOp[1+flags].p4type = P4_INT32;
        aOp[1+flags].p4.i = pTab->nCol+1;
        aOp[5].p2 = pTab->nCol;

        pParse->nVar = 1;
        pParse->nMem = 1;
        pParse->nTab = 1;
        sqlite3VdbeMakeReady(v, pParse);
      }
    }