integration/presto/src/main/prestodb/org/apache/carbondata/presto/impl/CarbonTableReader.java [178:242]:
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  private CarbonTableCacheModel parseCarbonMetadata(SchemaTableName table, String tablePath,
      Configuration config) {
    try {
      CarbonTableCacheModel cache = getValidCacheBySchemaTableName(table);
      if (cache != null) {
        return cache;
      }
      // multiple tasks can be launched in a worker concurrently. Hence need to synchronize this.
      synchronized (this) {
        // cache might be filled by another thread, so if filled use that cache.
        CarbonTableCacheModel cacheModel = getValidCacheBySchemaTableName(table);
        if (cacheModel != null) {
          return cacheModel;
        }
        // Step 1: get store path of the table and cache it.
        String schemaFilePath = CarbonTablePath.getSchemaFilePath(tablePath, config);
        // If metadata folder exists, it is a transactional table
        CarbonFile schemaFile = FileFactory.getCarbonFile(schemaFilePath, config);
        boolean isTransactionalTable = schemaFile.exists();
        org.apache.carbondata.format.TableInfo tableInfo;
        long modifiedTime = System.currentTimeMillis();
        if (isTransactionalTable) {
          //Step 2: read the metadata (tableInfo) of the table.
          ThriftReader.TBaseCreator createTBase = new ThriftReader.TBaseCreator() {
            // TBase is used to read and write thrift objects.
            // TableInfo is a kind of TBase used to read and write table information.
            // TableInfo is generated by thrift,
            // see schema.thrift under format/src/main/thrift for details.
            @Override
            public TBase create() {
              return new org.apache.carbondata.format.TableInfo();
            }
          };
          ThriftReader thriftReader = new ThriftReader(schemaFilePath, createTBase, config);
          thriftReader.open();
          tableInfo = (org.apache.carbondata.format.TableInfo) thriftReader.read();
          thriftReader.close();
          modifiedTime = schemaFile.getLastModifiedTime();
        } else {
          tableInfo = CarbonUtil.inferSchema(tablePath, table.getTableName(), false, config);
        }
        // Step 3: convert format level TableInfo to code level TableInfo
        SchemaConverter schemaConverter = new ThriftWrapperSchemaConverterImpl();
        // wrapperTableInfo is the code level information of a table in carbondata core,
        // different from the Thrift TableInfo.
        TableInfo wrapperTableInfo = schemaConverter
            .fromExternalToWrapperTableInfo(tableInfo, table.getSchemaName(), table.getTableName(),
                tablePath);
        wrapperTableInfo.setTransactionalTable(isTransactionalTable);
        CarbonMetadata.getInstance().removeTable(wrapperTableInfo.getTableUniqueName());
        // Step 4: Load metadata info into CarbonMetadata
        CarbonMetadata.getInstance().loadTableMetadata(wrapperTableInfo);
        CarbonTable carbonTable = Objects.requireNonNull(CarbonMetadata.getInstance()
            .getCarbonTable(table.getSchemaName(), table.getTableName()), "carbontable is null");
        refreshIndexInfo(carbonTable, config);
        cache = new CarbonTableCacheModel(modifiedTime, carbonTable);
        // cache the table
        carbonCache.get().put(table, cache);
        cache.setCarbonTable(carbonTable);
      }
      return cache;
    } catch (Exception ex) {
      throw new RuntimeException(ex);
    }
  }
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integration/presto/src/main/prestosql/org/apache/carbondata/presto/impl/CarbonTableReader.java [173:237]:
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  private CarbonTableCacheModel parseCarbonMetadata(SchemaTableName table, String tablePath,
      Configuration config) {
    try {
      CarbonTableCacheModel cache = getValidCacheBySchemaTableName(table);
      if (cache != null) {
        return cache;
      }
      // multiple tasks can be launched in a worker concurrently. Hence need to synchronize this.
      synchronized (this) {
        // cache might be filled by another thread, so if filled use that cache.
        CarbonTableCacheModel cacheModel = getValidCacheBySchemaTableName(table);
        if (cacheModel != null) {
          return cacheModel;
        }
        // Step 1: get store path of the table and cache it.
        String schemaFilePath = CarbonTablePath.getSchemaFilePath(tablePath, config);
        // If metadata folder exists, it is a transactional table
        CarbonFile schemaFile = FileFactory.getCarbonFile(schemaFilePath, config);
        boolean isTransactionalTable = schemaFile.exists();
        org.apache.carbondata.format.TableInfo tableInfo;
        long modifiedTime = System.currentTimeMillis();
        if (isTransactionalTable) {
          //Step 2: read the metadata (tableInfo) of the table.
          ThriftReader.TBaseCreator createTBase = new ThriftReader.TBaseCreator() {
            // TBase is used to read and write thrift objects.
            // TableInfo is a kind of TBase used to read and write table information.
            // TableInfo is generated by thrift,
            // see schema.thrift under format/src/main/thrift for details.
            @Override
            public TBase create() {
              return new org.apache.carbondata.format.TableInfo();
            }
          };
          ThriftReader thriftReader = new ThriftReader(schemaFilePath, createTBase, config);
          thriftReader.open();
          tableInfo = (org.apache.carbondata.format.TableInfo) thriftReader.read();
          thriftReader.close();
          modifiedTime = schemaFile.getLastModifiedTime();
        } else {
          tableInfo = CarbonUtil.inferSchema(tablePath, table.getTableName(), false, config);
        }
        // Step 3: convert format level TableInfo to code level TableInfo
        SchemaConverter schemaConverter = new ThriftWrapperSchemaConverterImpl();
        // wrapperTableInfo is the code level information of a table in carbondata core,
        // different from the Thrift TableInfo.
        TableInfo wrapperTableInfo = schemaConverter
            .fromExternalToWrapperTableInfo(tableInfo, table.getSchemaName(), table.getTableName(),
                tablePath);
        wrapperTableInfo.setTransactionalTable(isTransactionalTable);
        CarbonMetadata.getInstance().removeTable(wrapperTableInfo.getTableUniqueName());
        // Step 4: Load metadata info into CarbonMetadata
        CarbonMetadata.getInstance().loadTableMetadata(wrapperTableInfo);
        CarbonTable carbonTable = Objects.requireNonNull(CarbonMetadata.getInstance()
            .getCarbonTable(table.getSchemaName(), table.getTableName()), "carbontable is null");
        refreshIndexInfo(carbonTable, config);
        cache = new CarbonTableCacheModel(modifiedTime, carbonTable);
        // cache the table
        carbonCache.get().put(table, cache);
        cache.setCarbonTable(carbonTable);
      }
      return cache;
    } catch (Exception ex) {
      throw new RuntimeException(ex);
    }
  }
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