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Advanced SQL - Coggle Diagram

- - - - ordered sets of data
      - types
        
        b-trees
        
        balanced tree
        
        splits quantity of rows
        by half in each node
        
        useful with high
        cardinality
        
        hash-indexes
        
        codes values as hashes
        
        works with equality only
        
        smaller than b-tree,
        but equally fast
        
        might by created on-the-flight
        while joining tables
        
        bitmaps
        
        useful with low
        cardinality
        
        codes values into bits
        
        good for reads,
        bad for writes
        
        might by created on-the-flight
        from b-tree index
      - if where clause isn't selective enough,
        index won't be used
    - - by keys
      - local indexes
      - global indexes
  - - - compares all rows
      - loops for each row
    - - calculates hashes of keys
    - - sorts before merging
      - stops when found or
        impossible to find
      - loops once
- - - - Timeseries
      - Naturally partitioned data
  - - - DWH, on group
        attributes
      - many attributes
      - data analytics