[GitHub] [incubator-doris] kangpinghuang edited a comment on issue #1390: Support zone map for column

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kangpinghuang edited a comment on issue #1390: Support zone map for column
URL: https://github.com/apache/incubator-doris/issues/1390#issuecomment-508015441
 
 
   here is my design:
   
   1. define ZoneMap with serialize and deserialize
   class ZoneMap {
   public:
   serialize();
   deserialize();
   
   private:
   std::string min_value;
   std::string max_value;
   // if the whole page is null
   // if true, omit min_value and max_value
   bool is_null_page;
   };
   
   2. add ComparableEncoder to encode the value as comparable binary
   add a ComparableEncoder that can encode column value to comparable binary, and store them to ZoneMap.
   And then we can use binary to compare min/max value with predicate value directyly. do not have to care about the field type when filter the page
   
   3. define ZoneMapBuilder 
   class ZoneMapBuilder {
   Status add(ZoneMap zone_map);
   };
   add should call zone_map's serialize api and BinaryPlainPageBuilder to store the serialized zone map value.
   
   4. define ZoneMapDecoder
   class ZoneMapDecoder {
   Status load_zone_map(ColumnZoneMap* column_zone_map);
   };
   load_zone_map use BinaryPlainPageDecoder to get the serialized zone map and the call ZoneMap.deserialize the get ZoneMap and the ColumnZoneMap.add(zone_map) to construct column zone map.
   
   5. define ColumnZoneMap
   class ColumnZoneMap {
   Status add(ZoneMap page_zone_map);
   int compare_to_min(const std::string& value, int page_index);
   int compare_to_max(const std::string& value, int page_index);
   bool is_null_page(int page_index);
   
   private:
   int _page_size;
   // min value array
   std::string* _min_value;
   // max value array
   std::string* _max_value;
   bool* _is_null_pages;
   };
   
   

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