Class: Blazer::Adapters::ClickhouseAdapter

Inherits:
BaseAdapter
  • Object
show all
Defined in:
lib/blazer/adapters/clickhouse_adapter.rb

Constant Summary collapse

DATE_TIME_TYPES = 
["DateTime", "DateTime(%s)", "DateTime64(%d, %s)"].freeze

Instance Attribute Summary

Attributes inherited from BaseAdapter

#data_source

Instance Method Summary collapse

Methods inherited from BaseAdapter

#cachable?, #cancel, #cohort_analysis_statement, #cost, #initialize, #parameter_binding, #quoting, #reconnect, #supports_cohort_analysis?

Constructor Details

This class inherits a constructor from Blazer::Adapters::BaseAdapter

Instance Method Details

#explain(statement) ⇒ Object 



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# File 'lib/blazer/adapters/clickhouse_adapter.rb', line 53

def explain(statement)
  connection.explain(statement)
end

#preview_statement ⇒ Object 



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# File 'lib/blazer/adapters/clickhouse_adapter.rb', line 49

def preview_statement
  "SELECT * FROM {table} LIMIT 10"
end

#run_statement(statement, _comment) ⇒ Object 



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# File 'lib/blazer/adapters/clickhouse_adapter.rb', line 6

def run_statement(statement, _comment)
  columns = []
  rows = []
  error = nil

  begin
    result = connection.select_all(statement)
    unless result.data.blank?
      date_time_columns = result.meta
                                .select { |column| column["type"].in?(DATE_TIME_TYPES) }
                                .map { |column| column["name"] }
      columns = result.first.keys
      rows = result.map { |row| convert_time_columns(row, date_time_columns).values }
    end
  rescue => e
    error = e.message
  end

  [columns, rows, error]
end

#schema ⇒ Object 



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# File 'lib/blazer/adapters/clickhouse_adapter.rb', line 31

def schema
  statement = <<-SQL
    SELECT table, name, type
    FROM system.columns
    WHERE database = currentDatabase()
    ORDER BY table, position
  SQL

  response = connection.post(query: { query: statement, default_format: "CSV" })

  return [] if response.body.nil?

  response.body
          .group_by { |row| row[0] }
          .transform_values { |columns| columns.map { |c| { name: c[1], data_type: c[2] } } }
          .map { |table, columns| { schema: "public", table: table, columns: columns } }
end

#tables ⇒ Object 



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# File 'lib/blazer/adapters/clickhouse_adapter.rb', line 27

def tables
  connection.tables
end