SQLite

** the current value is always zero.)^
**
** [[SQLITE_DBSTATUS_CACHE_USED]] ^(<dt>SQLITE_DBSTATUS_CACHE_USED</dt>
** <dd>This parameter returns the approximate number of bytes of heap
** memory used by all pager caches associated with the database connection.)^
** ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_USED is always 0.
**
** [[SQLITE_DBSTATUS_PROPORTIONAL_CACHE_USED]] 
** ^(<dt>SQLITE_DBSTATUS_PROPORTIONAL_CACHE_USED</dt>
** <dd>This parameter is similar to DBSTATUS_CACHE_USED, except that if a
** pager cache is shared between two or more connections the bytes of heap
** memory used by that pager cache is divided evenly between the attached
** connections.)^  In other words, if none of the pager caches associated
** with the database connection are shared, this request returns the same
** value as DBSTATUS_CACHE_USED. Or, if one or more or the pager caches are
** shared, the value returned by this call will be smaller than that returned
** by DBSTATUS_CACHE_USED. ^The highwater mark associated with
** SQLITE_DBSTATUS_PROPORTIONAL_CACHE_USED is always 0.
**
** [[SQLITE_DBSTATUS_SCHEMA_USED]] ^(<dt>SQLITE_DBSTATUS_SCHEMA_USED</dt>
** <dd>This parameter returns the approximate number of bytes of heap
** memory used to store the schema for all databases associated
** with the connection - main, temp, and any [ATTACH]-ed databases.)^ 
** ^The full amount of memory used by the schemas is reported, even if the
** schema memory is shared with other database connections due to

#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_PROPORTIONAL_CACHE_USED 11
#define SQLITE_DBSTATUS_MAX                 11   /* Largest defined DBSTATUS */


/*
** CAPI3REF: Prepared Statement Status
** METHOD: sqlite3_stmt
**

    }

    /* 
    ** Return an approximation for the amount of memory currently used
    ** by all pagers associated with the given database connection.  The
    ** highwater mark is meaningless and is returned as zero.
    */
    case SQLITE_DBSTATUS_PROPORTIONAL_CACHE_USED:
    case SQLITE_DBSTATUS_CACHE_USED: {
      int totalUsed = 0;
      int i;
      sqlite3BtreeEnterAll(db);
      for(i=0; i<db->nDb; i++){
        Btree *pBt = db->aDb[i].pBt;
        if( pBt ){
          Pager *pPager = sqlite3BtreePager(pBt);
          int nByte = sqlite3PagerMemUsed(pPager);
          if( op==SQLITE_DBSTATUS_PROPORTIONAL_CACHE_USED ){
            nByte = nByte / sqlite3BtreeConnectionCount(pBt);
          }
          totalUsed += nByte;
        }
      }
      sqlite3BtreeLeaveAll(db);
      *pCurrent = totalUsed;

    { "LOOKASIDE_HIT",       SQLITE_DBSTATUS_LOOKASIDE_HIT       },
    { "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        },
    { "PROPORTIONAL_CACHE_USED", SQLITE_DBSTATUS_PROPORTIONAL_CACHE_USED },
  };
  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;

    do_test dbstatus-3.$tn.c { list $nAlloc1 $nStmt1 } [list $nAlloc3 $nStmt3]
    do_test dbstatus-3.$tn.d { list $nAlloc2 $nStmt2 } [list $nAlloc4 $nStmt4]
  }
}

#-------------------------------------------------------------------------
# The following tests focus on DBSTATUS_PROPORTIONAL_CACHE_USED
#
ifcapable shared_cache {
  proc do_cacheused_test {tn db res} {
    set cu [sqlite3_db_status $db SQLITE_DBSTATUS_CACHE_USED 0]
    set pcu [sqlite3_db_status $db SQLITE_DBSTATUS_PROPORTIONAL_CACHE_USED 0]
    set cu [lindex $cu 1]
    set pcu [lindex $pcu 1]
    uplevel [list do_test $tn [list list $cu $pcu] [list {*}$res]]
  }
  reset_db
  sqlite3 db file:test.db?cache=shared