text: #pragma once
  
  #include <Common/config.h>
  #if USE_MYSQL
  
  #include "IDictionarySource.h"
  #include "ExternalQueryBuilder.h"
  #include "DictionaryStructure.h"
  #include <common/LocalDateTime.h>
  #include <mysqlxx/PoolWithFailover.h>
  
  
  namespace Poco
  {
      class Logger;
  
      namespace Util
      {
          class AbstractConfiguration;
      }
  }
  
  
  namespace DB
  {
  
  
  /// Allows loading dictionaries from a MySQL database
  class MySQLDictionarySource final : public IDictionarySource
  {
  public:
      MySQLDictionarySource(const DictionaryStructure & dict_struct_,
          const Poco::Util::AbstractConfiguration & config, const std::string & config_prefix,
          const Block & sample_block);
  
      /// copy-constructor is provided in order to support cloneability
      MySQLDictionarySource(const MySQLDictionarySource & other);
  
      BlockInputStreamPtr loadAll() override;
  
      BlockInputStreamPtr loadUpdatedAll() override;
  
      BlockInputStreamPtr loadIds(const std::vector<UInt64> & ids) override;
  
      BlockInputStreamPtr loadKeys(
          const Columns & key_columns, const std::vector<size_t> & requested_rows) override;
  
      bool isModified() const override;
  
      bool supportsSelectiveLoad() const override;
  
      bool hasUpdateField() const override;
  
      DictionarySourcePtr clone() const override;
  
      std::string toString() const override;
  
  private:
      std::string getUpdateFieldAndDate();
  
      static std::string quoteForLike(const std::string s);
  
      LocalDateTime getLastModification() const;
  
      // execute invalidate_query. expects single cell in result
      std::string doInvalidateQuery(const std::string & request) const;
  
      Poco::Logger * log;
  
      std::chrono::time_point<std::chrono::system_clock> update_time;
      const DictionaryStructure dict_struct;
      const std::string db;
      const std::string table;
      const std::string where;
      const std::string update_field;
      const bool dont_check_update_time;
      Block sample_block;
      mutable mysqlxx::PoolWithFailover pool;
      ExternalQueryBuilder query_builder;
      const std::string load_all_query;
      LocalDateTime last_modification;
      std::string invalidate_query;
      mutable std::string invalidate_query_response;
  };
  
  }
  
  #endif
  