SQLite

  int pageSize;               /* Number of bytes in a page */
  Pgno mxPgno;                /* Maximum allowed size of the database */
  i64 journalSizeLimit;       /* Size limit for persistent journal files */
  char *zFilename;            /* Name of the database file */
  char *zJournal;             /* Name of the journal file */
  int (*xBusyHandler)(void*); /* Function to call when busy */
  void *pBusyHandlerArg;      /* Context argument for xBusyHandler */
  int aStat[4];               /* Total cache hits, misses, writes, spills */
#ifdef SQLITE_TEST
  int nRead;                  /* Database pages read */
#endif
  void (*xReiniter)(DbPage*); /* Call this routine when reloading pages */
  int (*xGet)(Pager*,Pgno,DbPage**,int); /* Routine to fetch a patch */
#ifdef SQLITE_HAS_CODEC
  void *(*xCodec)(void*,void*,Pgno,int); /* Routine for en/decoding data */

** Indexes for use with Pager.aStat[]. The Pager.aStat[] array contains
** the values accessed by passing SQLITE_DBSTATUS_CACHE_HIT, CACHE_MISS 
** or CACHE_WRITE to sqlite3_db_status().
*/
#define PAGER_STAT_HIT   0
#define PAGER_STAT_MISS  1
#define PAGER_STAT_WRITE 2
#define PAGER_STAT_SPILL 3

/*
** The following global variables hold counters used for
** testing purposes only.  These variables do not exist in
** a non-testing build.  These variables are not thread-safe.
*/
#ifdef SQLITE_TEST

  if( pPager->doNotSpill
   && ((pPager->doNotSpill & (SPILLFLAG_ROLLBACK|SPILLFLAG_OFF))!=0
      || (pPg->flags & PGHDR_NEED_SYNC)!=0)
  ){
    return SQLITE_OK;
  }

  pPager->aStat[PAGER_STAT_SPILL]++;
  pPg->pDirty = 0;
  if( pagerUseWal(pPager) ){
    /* Write a single frame for this page to the log. */
    rc = subjournalPageIfRequired(pPg); 
    if( rc==SQLITE_OK ){
      rc = pagerWalFrames(pPager, pPg, 0, 0);
    }

  a[9] = pPager->nRead;
  a[10] = pPager->aStat[PAGER_STAT_WRITE];
  return a;
}
#endif

/*
** Parameter eStat must be one of SQLITE_DBSTATUS_CACHE_HIT, _MISS, _WRITE,
** or _WRITE+1.  The SQLITE_DBSTATUS_CACHE_WRITE+1 case is a translation
** of SQLITE_DBSTATUS_CACHE_SPILL.  The _SPILL case is not contiguous because
** it was added later.
**
** Before returning, *pnVal is incremented by the
** current cache hit or miss count, according to the value of eStat. If the 
** reset parameter is non-zero, the cache hit or miss count is zeroed before 
** returning.
*/
void sqlite3PagerCacheStat(Pager *pPager, int eStat, int reset, int *pnVal){

  assert( eStat==SQLITE_DBSTATUS_CACHE_HIT
       || eStat==SQLITE_DBSTATUS_CACHE_MISS
       || eStat==SQLITE_DBSTATUS_CACHE_WRITE
       || eStat==SQLITE_DBSTATUS_CACHE_WRITE+1
  );

  assert( SQLITE_DBSTATUS_CACHE_HIT+1==SQLITE_DBSTATUS_CACHE_MISS );
  assert( SQLITE_DBSTATUS_CACHE_HIT+2==SQLITE_DBSTATUS_CACHE_WRITE );
  assert( PAGER_STAT_HIT==0 && PAGER_STAT_MISS==1
           && PAGER_STAT_WRITE==2 && PAGER_STAT_SPILL==3 );

  eStat -= SQLITE_DBSTATUS_CACHE_HIT;
  *pnVal += pPager->aStat[eStat];
  if( reset ){
    pPager->aStat[eStat] = 0;
  }
}

/*
** Return true if this is an in-memory or temp-file backed pager.
*/
int sqlite3PagerIsMemdb(Pager *pPager){

    iHiwtr = iCur = -1;
    sqlite3_db_status(db, SQLITE_DBSTATUS_CACHE_MISS, &iCur, &iHiwtr, 1);
    raw_printf(pArg->out, "Page cache misses:                   %d\n", iCur);
    iHiwtr = iCur = -1;
    sqlite3_db_status(db, SQLITE_DBSTATUS_CACHE_WRITE, &iCur, &iHiwtr, 1);
    raw_printf(pArg->out, "Page cache writes:                   %d\n", iCur);
    iHiwtr = iCur = -1;
    sqlite3_db_status(db, SQLITE_DBSTATUS_CACHE_SPILL, &iCur, &iHiwtr, 1);
    raw_printf(pArg->out, "Page cache spills:                   %d\n", iCur);
    iHiwtr = iCur = -1;
    sqlite3_db_status(db, SQLITE_DBSTATUS_SCHEMA_USED, &iCur, &iHiwtr, bReset);
    raw_printf(pArg->out, "Schema Heap Usage:                   %d bytes\n",
            iCur);
    iHiwtr = iCur = -1;
    sqlite3_db_status(db, SQLITE_DBSTATUS_STMT_USED, &iCur, &iHiwtr, bReset);
    raw_printf(pArg->out, "Statement Heap/Lookaside Usage:      %d bytes\n",
            iCur);

** wal file in wal mode databases, or the number of pages written to the
** database file in rollback mode databases. Any pages written as part of
** transaction rollback or database recovery operations are not included.
** If an IO or other error occurs while writing a page to disk, the effect
** on subsequent SQLITE_DBSTATUS_CACHE_WRITE requests is undefined.)^ ^The
** highwater mark associated with SQLITE_DBSTATUS_CACHE_WRITE is always 0.
** </dd>
**
** [[SQLITE_DBSTATUS_CACHE_SPILL]] ^(<dt>SQLITE_DBSTATUS_CACHE_SPILL</dt>
** <dd>This parameter returns the number of dirty cache entries that have
** been written to disk in the middle of a transaction due to the page
** cache overflowing. Transactions are more efficient if they are written
** to disk all at once. When pages spill mid-transaction, that introduces
** additional overhead. This parameter can be used help identify
** inefficiencies that can be resolve by increasing the cache size.
** </dd>
**
** [[SQLITE_DBSTATUS_DEFERRED_FKS]] ^(<dt>SQLITE_DBSTATUS_DEFERRED_FKS</dt>
** <dd>This parameter returns zero for the current value if and only if
** all foreign key constraints (deferred or immediate) have been
** resolved.)^  ^The highwater mark is always 0.
** </dd>
** </dl>
*/
#define SQLITE_DBSTATUS_LOOKASIDE_USED       0
#define SQLITE_DBSTATUS_CACHE_USED           1
#define SQLITE_DBSTATUS_SCHEMA_USED          2
#define SQLITE_DBSTATUS_STMT_USED            3
#define SQLITE_DBSTATUS_LOOKASIDE_HIT        4
#define SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE  5
#define SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL  6
#define SQLITE_DBSTATUS_CACHE_HIT            7
#define SQLITE_DBSTATUS_CACHE_MISS           8
#define SQLITE_DBSTATUS_CACHE_WRITE          9
#define SQLITE_DBSTATUS_DEFERRED_FKS        10
#define SQLITE_DBSTATUS_CACHE_USED_SHARED   11
#define SQLITE_DBSTATUS_CACHE_SPILL         12
#define SQLITE_DBSTATUS_MAX                 12   /* Largest defined DBSTATUS */


/*
** CAPI3REF: Prepared Statement Status
** METHOD: sqlite3_stmt
**
** ^(Each prepared statement maintains various

    }

    /*
    ** Set *pCurrent to the total cache hits or misses encountered by all
    ** pagers the database handle is connected to. *pHighwater is always set 
    ** to zero.
    */
    case SQLITE_DBSTATUS_CACHE_SPILL:
      op = SQLITE_DBSTATUS_CACHE_WRITE+1;
      /* Fall through into the next case */
    case SQLITE_DBSTATUS_CACHE_HIT:
    case SQLITE_DBSTATUS_CACHE_MISS:
    case SQLITE_DBSTATUS_CACHE_WRITE:{
      int i;
      int nRet = 0;
      assert( SQLITE_DBSTATUS_CACHE_MISS==SQLITE_DBSTATUS_CACHE_HIT+1 );
      assert( SQLITE_DBSTATUS_CACHE_WRITE==SQLITE_DBSTATUS_CACHE_HIT+2 );

    { "LOOKASIDE_MISS_SIZE", SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE },
    { "LOOKASIDE_MISS_FULL", SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL },
    { "CACHE_HIT",           SQLITE_DBSTATUS_CACHE_HIT           },
    { "CACHE_MISS",          SQLITE_DBSTATUS_CACHE_MISS          },
    { "CACHE_WRITE",         SQLITE_DBSTATUS_CACHE_WRITE         },
    { "DEFERRED_FKS",        SQLITE_DBSTATUS_DEFERRED_FKS        },
    { "CACHE_USED_SHARED",   SQLITE_DBSTATUS_CACHE_USED_SHARED   },
    { "CACHE_SPILL",         SQLITE_DBSTATUS_CACHE_SPILL         },
  };
  Tcl_Obj *pResult;
  if( objc!=4 ){
    Tcl_WrongNumArgs(interp, 1, objv, "DB PARAMETER RESETFLAG");
    return TCL_ERROR;
  }
  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ) return TCL_ERROR;

  set nMiss [sqlite3_db_status $db CACHE_MISS $reset]
  list $nHit $nMiss
}

proc db_write {db {reset 0}} {
  sqlite3_db_status $db CACHE_WRITE $reset
}

proc db_spill {db {reset 0}} {
  sqlite3_db_status $db CACHE_SPILL $reset
}

do_test 1.1 {
  db close
  sqlite3 db test.db
  execsql { PRAGMA mmap_size = 0 }
  expr {[file size test.db] / 1024}
} 6

}
do_test 2.7 { 
  execsql { INSERT INTO t1 VALUES(5, randomblob(600)) }
  db_write db
} {0 4 0}
do_test 2.8 { db_write db 1 } {0 4 0}
do_test 2.9 { db_write db 0 } {0 0 0}

do_test 3.0 { db_spill db 1 } {0 0 0}
do_test 3.1 { db_spill db 0 } {0 0 0}
do_execsql_test 3.2 {
  PRAGMA journal_mode=DELETE;
  PRAGMA cache_size=3;
  UPDATE t1 SET b=randomblob(1000);
} {delete}
do_test 3.2 { db_spill db 0 } {0 8 0}
 
finish_test