C++ Dictionary::getIndex方法代码示例

void GetTableCall::run() {
  DEBUG_PRINT("GetTableCall::run() [%s.%s]", arg1, arg2);
  NdbDictionary::Dictionary * dict;
  return_val = -1;
  
  if(strlen(arg1)) {
    arg0->ndb->setDatabaseName(arg1);
  }
  dict = arg0->ndb->getDictionary();
  ndb_table = dict->getTable(arg2);
  if(ndb_table) {
    return_val = dict->listIndexes(idx_list, arg2);
  }
  if(return_val == 0) {
    /* Fetch the indexes now.  These calls may perform network IO, populating 
       the (connection) global and (Ndb) local dictionary caches.  Later,
       in the JavaScript main thread, we will call getIndex() again knowing
       that the caches are populated.
    */
    for(unsigned int i = 0 ; i < idx_list.count ; i++) { 
      const NdbDictionary::Index * idx = dict->getIndex(idx_list.elements[i].name, arg2);
      /* It is possible to get an index for a recently dropped table rather 
         than the desired table.  This is a known bug likely to be fixed later.
      */
      if(ndb_table->getObjectVersion() != 
         dict->getTable(idx->getTable())->getObjectVersion()) 
      {
        dict->invalidateIndex(idx);
        idx = dict->getIndex(idx_list.elements[i].name, arg2);
      }
    }
  }
}

int
create_table() {
    NdbDictionary::Dictionary* dict = g_ndb->getDictionary();
    assert(dict);
    if(g_paramters[P_CREATE].value) {
        const NdbDictionary::Table * pTab = NDBT_Tables::getTable(g_table);
        assert(pTab);
        NdbDictionary::Table copy = * pTab;
        copy.setLogging(false);
        if(dict->createTable(copy) != 0) {
            g_err << "Failed to create table: " << g_table << endl;
            return -1;
        }

        NdbDictionary::Index x(g_ordered);
        x.setTable(g_table);
        x.setType(NdbDictionary::Index::OrderedIndex);
        x.setLogging(false);
        for (unsigned k = 0; k < copy.getNoOfColumns(); k++) {
            if(copy.getColumn(k)->getPrimaryKey()) {
                x.addColumn(copy.getColumn(k)->getName());
            }
        }

        if(dict->createIndex(x) != 0) {
            g_err << "Failed to create index: " << endl;
            return -1;
        }

        x.setName(g_unique);
        x.setType(NdbDictionary::Index::UniqueHashIndex);
        if(dict->createIndex(x) != 0) {
            g_err << "Failed to create index: " << endl;
            return -1;
        }
    }
    g_tab = dict->getTable(g_table);
    g_i_unique = dict->getIndex(g_unique, g_table);
    g_i_ordered = dict->getIndex(g_ordered, g_table);
    assert(g_tab);
    assert(g_i_unique);
    assert(g_i_ordered);
    return 0;
}

int
runInterpretedUKLookup(NDBT_Context* ctx, NDBT_Step* step)
{
  const NdbDictionary::Table * pTab = ctx->getTab();
  Ndb* pNdb = GETNDB(step);
  NdbDictionary::Dictionary * dict = pNdb->getDictionary();

  const NdbDictionary::Index* pIdx= dict->getIndex(pkIdxName, pTab->getName());
  CHK_RET_FAILED(pIdx != 0);

  const NdbRecord * pRowRecord = pTab->getDefaultRecord();
  CHK_RET_FAILED(pRowRecord != 0);
  const NdbRecord * pIdxRecord = pIdx->getDefaultRecord();
  CHK_RET_FAILED(pIdxRecord != 0);

  const Uint32 len = NdbDictionary::getRecordRowLength(pRowRecord);
  Uint8 * pRow = new Uint8[len];
  bzero(pRow, len);

  HugoCalculator calc(* pTab);
  calc.equalForRow(pRow, pRowRecord, 0);

  NdbTransaction* pTrans = pNdb->startTransaction();
  CHK_RET_FAILED(pTrans != 0);

  NdbInterpretedCode code;
  code.interpret_exit_ok();
  code.finalise();

  NdbOperation::OperationOptions opts;
  bzero(&opts, sizeof(opts));
  opts.optionsPresent = NdbOperation::OperationOptions::OO_INTERPRETED;
  opts.interpretedCode = &code;

  const NdbOperation * pOp = pTrans->readTuple(pIdxRecord, (char*)pRow,
                                               pRowRecord, (char*)pRow,
                                               NdbOperation::LM_Read,
                                               0,
                                               &opts,
                                               sizeof(opts));
  CHK_RET_FAILED(pOp);
  int res = pTrans->execute(Commit, AbortOnError);

  CHK_RET_FAILED(res == 0);

  delete [] pRow;

  return NDBT_OK;
}

int
create_table(){
  NdbDictionary::Dictionary* dict = g_ndb->getDictionary();
  assert(dict);
  if(g_paramters[P_CREATE].value){
    g_ndb->getDictionary()->dropTable(g_tablename);
    const NdbDictionary::Table * pTab = NDBT_Tables::getTable(g_tablename);
    assert(pTab);
    NdbDictionary::Table copy = * pTab;
    copy.setLogging(false);
    if(dict->createTable(copy) != 0){
      g_err << "Failed to create table: " << g_tablename << endl;
      return -1;
    }

    NdbDictionary::Index x(g_indexname);
    x.setTable(g_tablename);
    x.setType(NdbDictionary::Index::OrderedIndex);
    x.setLogging(false);
    for (unsigned k = 0; k < copy.getNoOfColumns(); k++){
      if(copy.getColumn(k)->getPrimaryKey()){
	x.addColumnName(copy.getColumn(k)->getName());
      }
    }

    if(dict->createIndex(x) != 0){
      g_err << "Failed to create index: " << endl;
      return -1;
    }
  }
  g_table = dict->getTable(g_tablename);
  g_index = dict->getIndex(g_indexname, g_tablename);
  assert(g_table);
  assert(g_index);

  if(g_paramters[P_CREATE].value)
  {
    int rows = g_paramters[P_ROWS].value;
    HugoTransactions hugoTrans(* g_table);
    if (hugoTrans.loadTable(g_ndb, rows)){
      g_err.println("Failed to load %s with %d rows", 
		    g_table->getName(), rows);
      return -1;
    }
  }
  
  return 0;
}

int
create_table(){
  NdbDictionary::Dictionary* dict = g_ndb->getDictionary();
  assert(dict);
  if(g_paramters[P_CREATE].value){
    g_ndb->getDictionary()->dropTable(g_tablename);
    const NdbDictionary::Table * pTab = NDBT_Tables::getTable(g_tablename);
    assert(pTab);
    NdbDictionary::Table copy = * pTab;
    copy.setLogging(false);
    if(dict->createTable(copy) != 0){
      g_err << "Failed to create table: " << g_tablename << endl;
      return -1;
    }

    NdbDictionary::Index x(g_indexname);
    x.setTable(g_tablename);
    x.setType(NdbDictionary::Index::OrderedIndex);
    x.setLogging(false);
    for (unsigned k = 0; k < (unsigned) copy.getNoOfColumns(); k++){
      if(copy.getColumn(k)->getPrimaryKey()){
	x.addColumnName(copy.getColumn(k)->getName());
      }
    }

    if(dict->createIndex(x) != 0){
      g_err << "Failed to create index: " << endl;
      return -1;
    }
  }
  g_table = dict->getTable(g_tablename);
  g_index = dict->getIndex(g_indexname, g_tablename);
  assert(g_table);
  assert(g_index);

  /* Obtain NdbRecord instances for the table and index */
  {
    NdbDictionary::RecordSpecification spec[ NDB_MAX_ATTRIBUTES_IN_TABLE ];
    
    Uint32 offset=0;
    Uint32 cols= g_table->getNoOfColumns();
    for (Uint32 colNum=0; colNum<cols; colNum++)
    {
      const NdbDictionary::Column* col= g_table->getColumn(colNum);
      Uint32 colLength= col->getLength();
      
      spec[colNum].column= col;
      spec[colNum].offset= offset;

      offset+= colLength;

      spec[colNum].nullbit_byte_offset= offset++;
      spec[colNum].nullbit_bit_in_byte= 0;
    }
  
    g_table_record= dict->createRecord(g_table,
                                       &spec[0],
                                       cols,
                                       sizeof(NdbDictionary::RecordSpecification));

    assert(g_table_record);
  }
  {
    NdbDictionary::RecordSpecification spec[ NDB_MAX_ATTRIBUTES_IN_TABLE ];
    
    Uint32 offset=0;
    Uint32 cols= g_index->getNoOfColumns();
    for (Uint32 colNum=0; colNum<cols; colNum++)
    {
      /* Get column from the underlying table */
      // TODO : Add this mechanism to dict->createRecord
      // TODO : Add NdbRecord queryability methods so that an NdbRecord can
      // be easily built and later used to read out data.
      const NdbDictionary::Column* col= 
        g_table->getColumn(g_index->getColumn(colNum)->getName());
      Uint32 colLength= col->getLength();
      
      spec[colNum].column= col;
      spec[colNum].offset= offset;

      offset+= colLength;

      spec[colNum].nullbit_byte_offset= offset++;
      spec[colNum].nullbit_bit_in_byte= 0;
    }
  
    g_index_record= dict->createRecord(g_index,
                                       &spec[0],
                                       cols,
                                       sizeof(NdbDictionary::RecordSpecification));

    assert(g_index_record);
  }


  if(g_paramters[P_CREATE].value)
  {
    int rows = g_paramters[P_ROWS].value;
    HugoTransactions hugoTrans(* g_table);
    if (hugoTrans.loadTable(g_ndb, rows)){
//.........这里部分代码省略.........

/* doAsyncCallback() runs in the main thread.  We don't want it to block.
   TODO: verify whether any IO is done 
         by checking WaitMetaRequestCount at the start and end.
*/    
void GetTableCall::doAsyncCallback(Local<Object> ctx) {
  const char *tableName;
  HandleScope scope;  
  DEBUG_PRINT("GetTableCall::doAsyncCallback: return_val %d", return_val);

  /* User callback arguments */
  Handle<Value> cb_args[2];
  cb_args[0] = Null();
  cb_args[1] = Null();
  
  /* TableMetadata = {
      database         : ""    ,  // Database name
      name             : ""    ,  // Table Name
      columns          : []    ,  // ordered array of DBColumn objects
      indexes          : []    ,  // array of DBIndex objects 
      partitionKey     : []    ,  // ordered array of column numbers in the partition key
    };
  */    
  if(ndb_table && ! return_val) {

    Local<Object> table = NdbDictTableEnv.newWrapper();
    const NdbDictionary::Table * js_ndb_table = ndb_table;
    wrapPointerInObject(js_ndb_table, NdbDictTableEnv, table);

    // database
    table->Set(String::NewSymbol("database"), String::New(arg1));
    
    // name
    tableName = ndb_table->getName();
    table->Set(String::NewSymbol("name"), String::New(tableName));

    // partitionKey
    int nPartitionKeys = 0;
    Handle<Array> partitionKeys = Array::New();
    table->Set(String::NewSymbol("partitionKey"), partitionKeys);
    
    // columns
    Local<Array> columns = Array::New(ndb_table->getNoOfColumns());
    for(int i = 0 ; i < ndb_table->getNoOfColumns() ; i++) {
      const NdbDictionary::Column *ndb_col = ndb_table->getColumn(i);
      Handle<Object> col = buildDBColumn(ndb_col);
      columns->Set(i, col);
      if(ndb_col->getPartitionKey()) { /* partition key */
        partitionKeys->Set(nPartitionKeys++, String::New(ndb_col->getName()));
      }
    }
    table->Set(String::NewSymbol("columns"), columns);

    // indexes (primary key & secondary) 
    Local<Array> js_indexes = Array::New(idx_list.count + 1);
    js_indexes->Set(0, buildDBIndex_PK());                   // primary key
    for(unsigned int i = 0 ; i < idx_list.count ; i++) {   // secondary indexes
      const NdbDictionary::Index * idx =
        dict->getIndex(idx_list.elements[i].name, arg2);
      js_indexes->Set(i+1, buildDBIndex(idx));
    }    
    table->Set(String::NewSymbol("indexes"), js_indexes, ReadOnly);
  
    // Table Record (implementation artifact; not part of spec)
    DEBUG_PRINT("Creating Table Record");
    Record * rec = new Record(dict, ndb_table->getNoOfColumns());
    for(int i = 0 ; i < ndb_table->getNoOfColumns() ; i++) {
      rec->addColumn(ndb_table->getColumn(i));
    }
    rec->completeTableRecord(ndb_table);

    table->Set(String::NewSymbol("record"), Record_Wrapper(rec));    

    // foreign keys (only foreign keys for which this table is the child)
    // now create the javascript foreign key metadata objects for dictionary objects cached earlier
    Local<Array> js_fks = Array::New(fk_count);

    int fk_number = 0;
    for(unsigned int i = 0 ; i < fk_list.count ; i++) {
      NdbDictionary::ForeignKey fk;
      if (fk_list.elements[i].type == NdbDictionary::Object::ForeignKey) {
        const char * fk_name = fk_list.elements[i].name;
        int fkGetCode = dict->getForeignKey(fk, fk_name);
        DEBUG_PRINT("getForeignKey for %s returned %i", fk_name, fkGetCode);
        // see if the foreign key child table is this table
        if(splitNameMatchesDbAndTable(fk.getChildTable())) {
          // the foreign key child table is this table; build the fk object
          DEBUG_PRINT("Adding foreign key for %s at %i", fk.getName(), fk_number);
          js_fks->Set(fk_number++, buildDBForeignKey(&fk));
        }
      }
    }
    table->Set(String::NewSymbol("foreignKeys"), js_fks, ReadOnly);

    // Autoincrement Cache Impl (also not part of spec)
    if(per_table_ndb) {
      table->Set(String::NewSymbol("per_table_ndb"), Ndb_Wrapper(per_table_ndb));
    }
    
    // User Callback
    cb_args[1] = table;
//.........这里部分代码省略.........

void GetTableCall::run() {
  DEBUG_PRINT("GetTableCall::run() [%s.%s]", arg1, arg2);
  return_val = -1;

  /* dbName is optional; if not present, set it from ndb database name */
  if(strlen(dbName)) {
    ndb->setDatabaseName(dbName);
  } else {
    dbName = ndb->getDatabaseName();
  }
  dict = ndb->getDictionary();
  ndb_table = dict->getTable(tableName);
  if(ndb_table) {
    /* Ndb object used to create NdbRecords and to cache auto-increment values */
    per_table_ndb = new Ndb(& ndb->get_ndb_cluster_connection());
    DEBUG_PRINT("per_table_ndb %s.%s %p\n", dbName, tableName, per_table_ndb);
    per_table_ndb->init();

    /* List the indexes */
    return_val = dict->listIndexes(idx_list, tableName);
  }
  if(return_val == 0) {
    /* Fetch the indexes now.  These calls may perform network IO, populating 
       the (connection) global and (Ndb) local dictionary caches.  Later,
       in the JavaScript main thread, we will call getIndex() again knowing
       that the caches are populated.
    */
    for(unsigned int i = 0 ; i < idx_list.count ; i++) { 
      const NdbDictionary::Index * idx = dict->getIndex(idx_list.elements[i].name, tableName);
      /* It is possible to get an index for a recently dropped table rather 
         than the desired table.  This is a known bug likely to be fixed later.
      */
      const char * idx_table_name = idx->getTable();
      const NdbDictionary::Table * idx_table = dict->getTable(idx_table_name);
      if(idx_table == 0 || idx_table->getObjectVersion() != ndb_table->getObjectVersion()) 
      {
        dict->invalidateIndex(idx);
        idx = dict->getIndex(idx_list.elements[i].name, tableName);
      }
    }
  }
  else {
    DEBUG_PRINT("listIndexes() returned %i", return_val);
    ndbError = & dict->getNdbError();
    return;
  }
  /* List the foreign keys and keep the list around for doAsyncCallback to create js objects
   * Currently there is no listForeignKeys so we use the more generic listDependentObjects
   * specifying the table metadata object.
   */
  return_val = dict->listDependentObjects(fk_list, *ndb_table);
  if (return_val == 0) {
    /* Fetch the foreign keys and associated parent tables now.
     * These calls may perform network IO, populating
     * the (connection) global and (Ndb) local dictionary caches.  Later,
     * in the JavaScript main thread, we will call getForeignKey() again knowing
     * that the caches are populated.
     * We only care about foreign keys where this table is the child table, not the parent table.
     */
    for(unsigned int i = 0 ; i < fk_list.count ; i++) {
      NdbDictionary::ForeignKey fk;
      if (fk_list.elements[i].type == NdbDictionary::Object::ForeignKey) {
        const char * fk_name = fk_list.elements[i].name;
        int fkGetCode = dict->getForeignKey(fk, fk_name);
        DEBUG_PRINT("getForeignKey for %s returned %i", fk_name, fkGetCode);
        // see if the foreign key child table is this table
        if(splitNameMatchesDbAndTable(fk.getChildTable())) {
          // the foreign key child table is this table; get the parent table
          ++fk_count;
          DEBUG_PRINT("Getting ParentTable");
          splitter.splitName(fk.getParentTable());
          ndb->setDatabaseName(splitter.part1);  // temp for next call
          const NdbDictionary::Table * parent_table = dict->getTable(splitter.part3);
          ndb->setDatabaseName(dbName);  // back to expected value
          DEBUG_PRINT("Parent table getTable returned %s", parent_table->getName());
        }
      }
    }
  }
  else {
    DEBUG_PRINT("listDependentObjects() returned %i", return_val);
    ndbError = & dict->getNdbError();
  }
}

int supersizeme(Ndb * ndb,char * db, char * tbl, bool ftScan, bool ignoreData)
{
  bool varFound;
  bool varFoundui;
  int dm_per_rec=0;
  int im_per_rec=0;
  int disk_per_rec=0;
  int noOfOrderedIndexes=0, noOfUniqueHashIndexes=0, noOfBlobs=0;
  int tmpDm=0,tmpIm=0, tmpDisk=0;
  ndb->setDatabaseName(db);
  NdbDictionary::Dictionary * dict  = ndb->getDictionary();
  const NdbDictionary::Table * table  = dict->getTable(tbl);
  if(table == 0)
    {
      printf( "table %s in database %s not found!\n", tbl,db);
      return -1;
    }

  bool isTable=false;
  
  
  printf("\nCalculating storage cost per record for table %s\n", table->getName());
  
  calculate_dm( ndb, table, NULL, tmpDm, tmpDisk, ftScan, noOfBlobs,ignoreData,varFound );
  // Gerald there is at least 1 PK (hidden or real) and not return by listIndexes()
  // So add according OH + increment noOfUniqueHashIndexes
  tmpIm = OH_PK;
  noOfUniqueHashIndexes++;
  
  dm_per_rec +=tmpDm;
  disk_per_rec +=tmpDisk;
  im_per_rec +=tmpIm;

  NdbDictionary::Dictionary::List list;
  dict->listIndexes(list, *table);   
  int no_attrs=table->getNoOfColumns();
  for (unsigned i = 0; i < list.count; i++) 
  {      
    NdbDictionary::Dictionary::List::Element& elt = list.elements[i];

    if (verbose) 
    {
        printf("Analysing element : %s, Type : %s \n",
               elt.name, elementTypeStr[elt.type] );
    }
    switch (elt.type) 
    {
      case NdbDictionary::Object::UniqueHashIndex:
	    {
	      const NdbDictionary::Index * ix  = dict->getIndex(elt.name, table->getName());
	      printf(  "---\tWARNING! Unique Index found named (\"%s\"): \n",elt.name);
	      int pk_cols=0;
	      calculate_dm_ui(ndb, table, ix, tmpDm, tmpDisk, ftScan, noOfBlobs, pk_cols,varFoundui);
	      printf(  "---\t\tUnique Index Cost -  DataMemory per record = %d and IndexMemory  = %d\n", tmpDm, tmpIm );
	      //Gerald : OH_PK already include and OH_UNIQUE8HASH_INDEX is included by calculate_dm_ui
          // tmpIm = OH_PK;
	      dm_per_rec += tmpDm;
	      disk_per_rec += tmpDisk;
	      im_per_rec += tmpIm;
	      isTable = true;
	      noOfUniqueHashIndexes++;
	      //no_attrs+=(ix->getNoOfColumns()+pk_cols);
        }
        break;

      case NdbDictionary::Object::OrderedIndex:
	    tmpDm = OH_ORDERED_INDEX;
	    tmpIm = 0;
	    printf(  "---\tOrdered Index found named (%s"
		         "). Additional cost per record is = %d" 
		         " bytes of DataMemory.\n",
		         elt.name, tmpDm  );
	    dm_per_rec += tmpDm;
	    isTable = true;
	    noOfOrderedIndexes++;
	    break;

      default: 
	    break;
    }
  }


  int rows = 0;
  
  if (select_count(ndb, table, 240, &rows, 
		   NdbOperation::LM_CommittedRead) <0){
    printf( "counting rows failed\n" );
    return 0;
  }
  
  printf("\nRecord size (incl OH):"
	 "\n\t#Rows found=%d records "  
	 "\n\t#OrderedIndexes=%d"  
	 "\n\t#UniqueHashIndexes=%d "  
	 "\n\t#blob/text=%d "  
	 "\n\t#attributes=%d "  
	 "\n\tDataMemory=%d bytes "  
	 "\n\tIndexMemory=%d bytes" 
	 "\n\tDiskspace=%d bytes\n\n",
//.........这里部分代码省略.........

int
runBasic(NDBT_Context* ctx, NDBT_Step* step)
{
    Uint32 useRangeScanT1 = ctx->getProperty("UseRangeScanT1", (uint32)0);

    Ndb* pNdb = GETNDB(step);
    NdbDictionary::Dictionary * pDict = pNdb->getDictionary();
    int records = ctx->getNumRecords();
    int result = NDBT_OK;

    int l = 0;
    while (!ctx->isTestStopped())
    {
        for (unsigned i = 0; i<table_list.size(); i++)
        {
            const NdbDictionary::Table* tab = pDict->getTable(table_list[i].c_str());
            HugoTransactions trans(* tab);
            switch(l % 4) {
            case 0:
                trans.loadTable(pNdb, records);
                trans.scanUpdateRecords(pNdb, records);
                trans.pkUpdateRecords(pNdb, records);
                trans.pkReadUnlockRecords(pNdb, records);
                break;
            case 1:
                trans.scanUpdateRecords(pNdb, records);
                // TODO make pkInterpretedUpdateRecords work on any table
                // (or check if it does)
                if (strcmp(tab->getName(), "T1") == 0)
                    trans.pkInterpretedUpdateRecords(pNdb, records);
                if (strcmp(tab->getName(), "T1") == 0 &&
                        useRangeScanT1)
                {
                    const NdbDictionary::Index* pInd = pDict->getIndex("T1X1", "T1");
                    if (pInd == 0)
                    {
                        g_err << "getIndex(T1X1) error: " << pDict->getNdbError() << endl;
                        return NDBT_FAILED;
                    }
                    // bug#13834481 - bound values do not matter
                    const Uint32 lo = 0x11110000;
                    const Uint32 hi = 0xaaaa0000;
                    HugoTransactions::HugoBound bound_arr[6];
                    int bound_cnt = 0;
                    for (int j = 0; j <= 1; j++) {
                        int n = rand() % 4;
                        for (int i = 0; i < n; i++) {
                            HugoTransactions::HugoBound& b = bound_arr[bound_cnt++];
                            b.attr = i;
                            b.type = (j == 0 ? 0 : 2); // LE/GE
                            b.value = (j == 0 ? &lo : &hi);
                        }
                    }
                    g_info << "range scan T1 with " << bound_cnt << " bounds" << endl;
                    if (trans.scanReadRecords(pNdb, pInd, records, 0, 0,
                                              NdbOperation::LM_Read, 0, bound_cnt, bound_arr) != 0)
                    {
                        const NdbError& err = trans.getNdbError();
                        /*
                         * bug#13834481 symptoms include timeouts and error 1231.
                         * Check for any non-temporary error.
                         */
                        if (err.status == NdbError::TemporaryError)
                        {
                            g_info << "range scan T1 temporary error: " << err << endl;
                        }
                        if (err.status != NdbError::TemporaryError)
                        {
                            g_err << "range scan T1 permanent error: " << err << endl;
                            return NDBT_FAILED;
                        }
                    }
                }
                trans.clearTable(pNdb, records/2);
                trans.loadTable(pNdb, records/2);
                break;
            case 2:
                trans.clearTable(pNdb, records/2);
                trans.loadTable(pNdb, records/2);
                trans.clearTable(pNdb, records/2);
                break;
            case 3:
                if (createDropEvent(ctx, step))
                {
                    return NDBT_FAILED;
                }
                break;
            }
        }
        l++;
    }

    return result;
}

/* doAsyncCallback() runs in the main thread.  We don't want it to block.
   TODO: verify whether any IO is done 
         by checking WaitMetaRequestCount at the start and end.
*/    
void GetTableCall::doAsyncCallback(Local<Object> ctx) {
  const char *ndbTableName;
  EscapableHandleScope scope(isolate);
  DEBUG_PRINT("GetTableCall::doAsyncCallback: return_val %d", return_val);

  /* User callback arguments */
  Handle<Value> cb_args[2];
  cb_args[0] = Null(isolate);
  cb_args[1] = Null(isolate);
  
  /* TableMetadata = {
      database         : ""    ,  // Database name
      name             : ""    ,  // Table Name
      columns          : []    ,  // ordered array of DBColumn objects
      indexes          : []    ,  // array of DBIndex objects 
      partitionKey     : []    ,  // ordered array of column numbers in the partition key
      sparseContainer  : null     // default column for sparse fields
    };
  */    
  if(ndb_table && ! return_val) {
    Local<Object> table = NdbDictTableEnv.wrap(ndb_table)->ToObject();

    // database
    table->Set(SYMBOL(isolate, "database"), String::NewFromUtf8(isolate, arg1));
    
    // name
    ndbTableName = ndb_table->getName();
    table->Set(SYMBOL(isolate, "name"), String::NewFromUtf8(isolate, ndbTableName));

    // partitionKey
    int nPartitionKeys = 0;
    Handle<Array> partitionKeys = Array::New(isolate);
    table->Set(SYMBOL(isolate, "partitionKey"), partitionKeys);

    // sparseContainer
    table->Set(SYMBOL(isolate,"sparseContainer"), Null(isolate));

    // columns
    Local<Array> columns = Array::New(isolate, ndb_table->getNoOfColumns());
    for(int i = 0 ; i < ndb_table->getNoOfColumns() ; i++) {
      const NdbDictionary::Column *ndb_col = ndb_table->getColumn(i);
      Handle<Object> col = buildDBColumn(ndb_col);
      columns->Set(i, col);
      if(ndb_col->getPartitionKey()) { /* partition key */
        partitionKeys->Set(nPartitionKeys++, String::NewFromUtf8(isolate, ndb_col->getName()));
      }
      if(     ! strcmp(ndb_col->getName(), "SPARSE_FIELDS")
          && ( (! strncmp(getColumnType(ndb_col), "VARCHAR", 7)
                  && (getEncoderCharsetForColumn(ndb_col)->isUnicode))
              || (   ! strncmp(getColumnType(ndb_col), "VARBINARY", 9)
                  || ! strncmp(getColumnType(ndb_col), "JSON", 4))))
      {
        table->Set(SYMBOL(isolate,"sparseContainer"),
                   String::NewFromUtf8(isolate, ndb_col->getName()));
      }
    }
    table->Set(SYMBOL(isolate, "columns"), columns);

    // indexes (primary key & secondary) 
    Local<Array> js_indexes = Array::New(isolate, idx_list.count + 1);
    js_indexes->Set(0, buildDBIndex_PK());                   // primary key
    for(unsigned int i = 0 ; i < idx_list.count ; i++) {   // secondary indexes
      const NdbDictionary::Index * idx =
        dict->getIndex(idx_list.elements[i].name, arg2);
      js_indexes->Set(i+1, buildDBIndex(idx));
    }    
    SET_RO_PROPERTY(table, SYMBOL(isolate, "indexes"), js_indexes);

    // foreign keys (only foreign keys for which this table is the child)
    // now create the javascript foreign key metadata objects for dictionary objects cached earlier
    Local<Array> js_fks = Array::New(isolate, fk_count);

    int fk_number = 0;
    for(unsigned int i = 0 ; i < fk_list.count ; i++) {
      NdbDictionary::ForeignKey fk;
      if (fk_list.elements[i].type == NdbDictionary::Object::ForeignKey) {
        const char * fk_name = fk_list.elements[i].name;
        int fkGetCode = dict->getForeignKey(fk, fk_name);
        DEBUG_PRINT("getForeignKey for %s returned %i", fk_name, fkGetCode);
        // see if the foreign key child table is this table
        if(splitNameMatchesDbAndTable(fk.getChildTable())) {
          // the foreign key child table is this table; build the fk object
          DEBUG_PRINT("Adding foreign key for %s at %i", fk.getName(), fk_number);
          js_fks->Set(fk_number++, buildDBForeignKey(&fk));
        }
      }
    }
    SET_RO_PROPERTY(table, SYMBOL(isolate, "foreignKeys"), js_fks);

    // Autoincrement Cache Impl (also not part of spec)
    if(per_table_ndb) {
      table->Set(SYMBOL(isolate, "per_table_ndb"), Ndb_Wrapper(per_table_ndb));
    }
    
    // User Callback
    cb_args[1] = table;
//.........这里部分代码省略.........