SQLite

      pIdxInfo->aConstraintUsage[iScopeTerm].argvIndex = idx++;
      pIdxInfo->aConstraintUsage[iScopeTerm].omit = 1;
    }
    if( iPlan&(16|32) ){
      pIdxInfo->aConstraintUsage[iDistTerm].argvIndex = idx++;
      pIdxInfo->aConstraintUsage[iDistTerm].omit = 1;
    }
    pIdxInfo->estimatedCost = 1e5;
  }else{
    pIdxInfo->idxNum = 0;
    pIdxInfo->estimatedCost = 1e50;
  }
  return SQLITE_OK;
}

/*
** Open a new fuzzy-search cursor.
*/

  int nOps,
  int (*xProgress)(void*), 
  void *pArg
){
  sqlite3_mutex_enter(db->mutex);
  if( nOps>0 ){
    db->xProgress = xProgress;
    db->nProgressOps = (unsigned)nOps;
    db->pProgressArg = pArg;
  }else{
    db->xProgress = 0;
    db->nProgressOps = 0;
    db->pProgressArg = 0;
  }
  sqlite3_mutex_leave(db->mutex);

    { "short_column_names",       SQLITE_ShortColNames },
    { "count_changes",            SQLITE_CountRows     },
    { "empty_result_callbacks",   SQLITE_NullCallback  },
    { "legacy_file_format",       SQLITE_LegacyFileFmt },
    { "fullfsync",                SQLITE_FullFSync     },
    { "checkpoint_fullfsync",     SQLITE_CkptFullFSync },
    { "reverse_unordered_selects", SQLITE_ReverseOrder  },
    { "query_only",               SQLITE_QueryOnly     },
#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
    { "automatic_index",          SQLITE_AutoIndex     },
#endif
#ifdef SQLITE_DEBUG
    { "sql_trace",                SQLITE_SqlTrace      },
    { "vdbe_listing",             SQLITE_VdbeListing   },
    { "vdbe_trace",               SQLITE_VdbeTrace     },

  int (*xAuth)(void*,int,const char*,const char*,const char*,const char*);
                                /* Access authorization function */
  void *pAuthArg;               /* 1st argument to the access auth function */
#endif
#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
  int (*xProgress)(void *);     /* The progress callback */
  void *pProgressArg;           /* Argument to the progress callback */
  unsigned nProgressOps;        /* Number of opcodes for progress callback */
#endif
#ifndef SQLITE_OMIT_VIRTUALTABLE
  int nVTrans;                  /* Allocated size of aVTrans */
  Hash aModule;                 /* populated by sqlite3_create_module() */
  VtabCtx *pVtabCtx;            /* Context for active vtab connect/create */
  VTable **aVTrans;             /* Virtual tables with open transactions */
  VTable *pDisconnect;    /* Disconnect these in next sqlite3_prepare() */

#define SQLITE_RecTriggers    0x00020000  /* Enable recursive triggers */
#define SQLITE_ForeignKeys    0x00040000  /* Enforce foreign key constraints  */
#define SQLITE_AutoIndex      0x00080000  /* Enable automatic indexes */
#define SQLITE_PreferBuiltin  0x00100000  /* Preference to built-in funcs */
#define SQLITE_LoadExtension  0x00200000  /* Enable load_extension */
#define SQLITE_EnableTrigger  0x00400000  /* True to enable triggers */
#define SQLITE_DeferFKs       0x00800000  /* Defer all FK constraints */
#define SQLITE_QueryOnly      0x01000000  /* Disable database changes */


/*
** Bits of the sqlite3.dbOptFlags field that are used by the
** sqlite3_test_control(SQLITE_TESTCTRL_OPTIMIZATIONS,...) interface to
** selectively disable various optimizations.
*/
#define SQLITE_QueryFlattener 0x0001   /* Query flattening */

  int pc=0;                  /* The program counter */
  Op *aOp = p->aOp;          /* Copy of p->aOp */
  Op *pOp;                   /* Current operation */
  int rc = SQLITE_OK;        /* Value to return */
  sqlite3 *db = p->db;       /* The database */
  u8 resetSchemaOnFault = 0; /* Reset schema after an error if positive */
  u8 encoding = ENC(db);     /* The database encoding */
  int iCompare = 0;          /* Result of last OP_Compare operation */
  unsigned nVmStep = 0;      /* Number of virtual machine steps */
#ifndef SQLITE_OMIT_PROGRESS_CALLBACK

  unsigned nProgressOps = 0; /* nVmStep at last progress callback. */
#endif


  Mem *aMem = p->aMem;       /* Copy of p->aMem */
  Mem *pIn1 = 0;             /* 1st input operand */
  Mem *pIn2 = 0;             /* 2nd input operand */
  Mem *pIn3 = 0;             /* 3rd input operand */
  Mem *pOut = 0;             /* Output operand */
  int *aPermute = 0;         /* Permutation of columns for OP_Compare */
  i64 lastRowid = db->lastRowid;  /* Saved value of the last insert ROWID */

  assert( p->bIsReader || p->readOnly!=0 );
  p->rc = SQLITE_OK;
  assert( p->explain==0 );
  p->pResultSet = 0;
  db->busyHandler.nBusy = 0;
  CHECK_FOR_INTERRUPT;
  sqlite3VdbeIOTraceSql(p);



#ifdef SQLITE_DEBUG
  sqlite3BeginBenignMalloc();
  if( p->pc==0  && (p->db->flags & SQLITE_VdbeListing)!=0 ){
    int i;
    printf("VDBE Program Listing:\n");
    sqlite3VdbePrintSql(p);
    for(i=0; i<p->nOp; i++){

#ifdef SQLITE_TEST
    if( sqlite3_interrupt_count>0 ){
      sqlite3_interrupt_count--;
      if( sqlite3_interrupt_count==0 ){
        sqlite3_interrupt(db);
      }
    }





















#endif

    /* On any opcode with the "out2-prerelease" tag, free any
    ** external allocations out of mem[p2] and set mem[p2] to be
    ** an undefined integer.  Opcodes will either fill in the integer
    ** value or convert mem[p2] to a different type.
    */

**
** An unconditional jump to address P2.
** The next instruction executed will be 
** the one at index P2 from the beginning of
** the program.
*/
case OP_Goto: {             /* jump */
  pc = pOp->p2 - 1;

  /* Opcodes that are used as the bottom of a loop (OP_Next, OP_Prev,
  ** OP_VNext, OP_RowSetNext, or OP_SorterNext) all jump here upon
  ** completion.  Check to see if sqlite3_interrupt() has been called
  ** or if the progress callback needs to be invoked. 
  **
  ** This code uses unstructured "goto" statements and does not look clean.
  ** But that is not due to sloppy coding habits. The code is written this
  ** way for performance, to avoid having to run the interrupt and progress
  ** checks on every opcode.  This helps sqlite3_step() to run about 1.5%
  ** faster according to "valgrind --tool=cachegrind" */
check_for_interrupt:
  CHECK_FOR_INTERRUPT;
#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
  /* Call the progress callback if it is configured and the required number
  ** of VDBE ops have been executed (either since this invocation of
  ** sqlite3VdbeExec() or since last time the progress callback was called).
  ** If the progress callback returns non-zero, exit the virtual machine with
  ** a return code SQLITE_ABORT.
  */
  if( db->xProgress!=0 && (nVmStep - nProgressOps)>=db->nProgressOps ){
    int prc;
    prc = db->xProgress(db->pProgressArg);
    if( prc!=0 ){
      rc = SQLITE_INTERRUPT;
      goto vdbe_error_halt;
    }
    nProgressOps = nVmStep;
  }
#endif
  
  break;
}

/* Opcode:  Gosub P1 P2 * * *
**
** Write the current address onto register P1
** and then jump to address P2.

case OP_Transaction: {
  Btree *pBt;

  assert( p->bIsReader );
  assert( p->readOnly==0 || pOp->p2==0 );
  assert( pOp->p1>=0 && pOp->p1<db->nDb );
  assert( (p->btreeMask & (((yDbMask)1)<<pOp->p1))!=0 );
  if( pOp->p2 && (db->flags & SQLITE_QueryOnly)!=0 ){
    rc = SQLITE_READONLY;
    goto abort_due_to_error;
  }
  pBt = db->aDb[pOp->p1].pBt;

  if( pBt ){
    rc = sqlite3BtreeBeginTrans(pBt, pOp->p2);
    if( rc==SQLITE_BUSY ){
      p->pc = pc;
      p->rc = rc = SQLITE_BUSY;

*/
case OP_SorterNext:    /* jump */
case OP_Prev:          /* jump */
case OP_Next: {        /* jump */
  VdbeCursor *pC;
  int res;


  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  assert( pOp->p5<=ArraySize(p->aCounter) );
  pC = p->apCsr[pOp->p1];
  if( pC==0 ){
    break;  /* See ticket #2273 */
  }
  assert( pC->isSorter==(pOp->opcode==OP_SorterNext) );

    pc = pOp->p2 - 1;
    if( pOp->p5 ) p->aCounter[pOp->p5-1]++;
#ifdef SQLITE_TEST
    sqlite3_search_count++;
#endif
  }
  pC->rowidIsValid = 0;
  goto check_for_interrupt;
}

/* Opcode: IdxInsert P1 P2 P3 * P5
**
** Register P2 holds an SQL index key made using the
** MakeRecord instructions.  This opcode writes that key
** into the index P1.  Data for the entry is nil.

**
** Extract the smallest value from boolean index P1 and put that value into
** register P3.  Or, if boolean index P1 is initially empty, leave P3
** unchanged and jump to instruction P2.
*/
case OP_RowSetRead: {       /* jump, in1, out3 */
  i64 val;

  pIn1 = &aMem[pOp->p1];
  if( (pIn1->flags & MEM_RowSet)==0 
   || sqlite3RowSetNext(pIn1->u.pRowSet, &val)==0
  ){
    /* The boolean index is empty */
    sqlite3VdbeMemSetNull(pIn1);
    pc = pOp->p2 - 1;
  }else{
    /* A value was pulled from the index */
    sqlite3VdbeMemSetInt64(&aMem[pOp->p3], val);
  }
  goto check_for_interrupt;
}

/* Opcode: RowSetTest P1 P2 P3 P4
**
** Register P3 is assumed to hold a 64-bit integer value. If register P1
** contains a RowSet object and that RowSet object contains
** the value held in P3, jump to register P2. Otherwise, insert the

    res = pModule->xEof(pCur->pVtabCursor);
  }

  if( !res ){
    /* If there is data, jump to P2 */
    pc = pOp->p2 - 1;
  }
  goto check_for_interrupt;
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */

#ifndef SQLITE_OMIT_VIRTUALTABLE
/* Opcode: VRename P1 * * P4 *
**
** P4 is a pointer to a virtual table object, an sqlite3_vtab structure.

    INSERT INTO abc VALUES(4, 5, 6);
    INSERT INTO abc VALUES(7, 8, 9);
  }

  set ::res [list]
  db eval {SELECT a, b, c FROM abc} {
    lappend ::res $a $b $c
    db progress 5 "expr 1"
    catch {db eval {SELECT a, b, c FROM abc} { }} msg
    lappend ::res $msg
  }

  set ::res
} {1 2 3 interrupted 4 5 6 interrupted 7 8 9 interrupted}

# 2013-07-11
#
# 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.
#
#***********************************************************************
# This file implements regression tests for SQLite library.
#
# This file tests the "query_only" pragma.
#

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

do_execsql_test queryonly-1.1 {
  CREATE TABLE t1(a);
  INSERT INTO t1 VALUES(123),(456);
  SELECT a FROM t1 ORDER BY a;
} {123 456}
do_execsql_test queryonly-1.2 {
  PRAGMA query_only;
} {0}
do_execsql_test queryonly-1.3 {
  PRAGMA query_only=ON;
  PRAGMA query_only;
} {1}
do_test queryonly-1.4 {
  catchsql {INSERT INTO t1 VALUES(789);}
} {1 {attempt to write a readonly database}}
do_test queryonly-1.5 {
  catchsql {DELETE FROM t1;}
} {1 {attempt to write a readonly database}}
do_test queryonly-1.6 {
  catchsql {UPDATE t1 SET a=a+1;}
} {1 {attempt to write a readonly database}}
do_test queryonly-1.7 {
  catchsql {CREATE TABLE t2(b);}
} {1 {attempt to write a readonly database}}
do_test queryonly-1.8 {
  catchsql {CREATE INDEX t1a ON t1(a);}
} {1 {attempt to write a readonly database}}
do_test queryonly-1.9 {
  catchsql {DROP TABLE t1;}
} {1 {attempt to write a readonly database}}
do_test queryonly-1.10 {
  catchsql {ANALYZE;}
} {1 {attempt to write a readonly database}}
do_execsql_test queryonly-1.11 {
  SELECT a FROM t1 ORDER BY a;
} {123 456}

do_execsql_test queryonly-2.2 {
  PRAGMA query_only;
} {1}
do_execsql_test queryonly-2.3 {
  PRAGMA query_only=OFF;
  PRAGMA query_only;
} {0}
do_execsql_test queryonly-2.4 {
  INSERT INTO t1 VALUES(789);
  SELECT a FROM t1 ORDER BY a;
} {123 456 789}
do_execsql_test queryonly-2.5 {
  UPDATE t1 SET a=a+1;
  SELECT a FROM t1 ORDER BY a;
} {124 457 790}

finish_test