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Presto (Data Sources (Connector (A connector adapts Presto to a data…

- - - - clauses
      - expressions
      - predicates
  - - - it converts it into a query
        
        creates a distributed query plan
        
        then realizes as a series of interconnected stages running on Presto workers
    - - When Presto executes a query, it does so by breaking up the execution into a hierarchy of stages
      - Stages = tree
        
        Every query has a root stage which is responsible for aggregating the output from other stages
      - Stages are what the coordinator uses to model a distributed query plan
      - don't run on Presto workers
      - Task
        
        Is implemented as a series of tasks distributed over a network of Presto workers
        
        query plan -> stages -> tasks
        
        has inputs and outputs
        
        Split
        
        Tasks operate on splits which are sections of a larger data set
        
        Stages at the lowest level of a distributed query plan retrieve data via splits from connectors, and intermediate stages at a higher level of a distributed query plan retrieve data from other stages
        
        Driver
        
        Tasks contain one or more parallel drivers
        
        Drivers act upon data and combine operators to produce output that is then aggregated by a task and then delivered to another task in another stage
        
        Is a sequence of operator instances or a physical set of operators in memory
        
        Is the lowest level of parallelism in the Presto architecture
        
        has one input and one output
    - - Consumes data
      - transforms data
      - produces data
    - - transfer data between Presto nodes for different stages of a query
      - produce data into an output buffer and consume data from other tasks using an exchange client.