Class: DWH::Adapters::MySql

Inherits:
Adapter
  • Object
show all
Defined in:
lib/dwh/adapters/my_sql.rb

Overview

MySql Adapter. To use this adapter make sure you have the MySql2 Gem installed. You can also pass additional connection properties via Adapter#extra_connection_params config property.

MySql concept of database maps to schema in this adapter. This is only important for the metadata methods where you want to pull up tables from a different database (aka schema).

Examples:

Connecting to Localhost

Please use 127.0.0.1 when using a local docker instance to run MySQl.
Otherwise the Gem will try to connect over unix socket.

DWH.create(:mysql, { host: '127.0.0.1', databse: 'mydb', username: 'me', password: 'mypwd', client_name: 'Strata CLI'})

Connecting with SSL

DWH.create(:mysql, { host: '127.0.0.1', databse: 'mydb',
    username: 'me', password: 'mypwd', ssl: true}) # this will default ssl_mode to required

Modify the SSL mode. All extra ssl config can be passed this way.

DWH.create(:mysql, { host: '127.0.0.1', databse: 'mydb',
    username: 'me', password: 'mypwd', ssl: true,
    extra_connection_params: {ssl_mode: "verify"})

Constant Summary

Constants included from Settings

Settings::BASE_SETTINGS_FILE

Constants included from Functions::Dates

Functions::Dates::DATE_CLASSES, Functions::Dates::TIMESTAMPABLE_UNITS

Instance Attribute Summary

Attributes inherited from Adapter

#config, #settings

Attributes included from Settings

#adapter_settings

Instance Method Summary collapse

Methods inherited from Adapter

#adapter_name, #alter_settings, #close, config, configuration, #connect!, #connect?, #extra_connection_params, #extra_query_params, #initialize, #reset_settings, #table?, #token_expired?, #with_debug, #with_retry

Methods included from Settings

#adapter_name, #load_settings, #settings_file, #settings_file_path, #using_base_settings?

Methods included from Logger

#logger, logger

Methods included from Behaviors

#apply_advanced_filtering_on_array_projections?, #cross_universe_measure_filtering_strategy, #extend_ending_date_to_last_hour_of_day?, #final_measure_filter?, #final_pass_measure_join_type, #greedy_apply_date_filters, #intermediate_measure_filter?, #temp_table_prefix, #temp_table_type

Methods included from Functions

#cast, #cross_join, #gsk, #lower_case, #quote, #string_lit, #trim, #upper_case

Methods included from Functions::Arrays

#array_exclude_list, #array_in_list, #array_unnest_join

Methods included from Functions::Nulls

#if_null, #null_if, #null_if_zero

Methods included from Functions::ExtractDatePart

#extract_day_name, #extract_day_of_month, #extract_day_of_week, #extract_day_of_year, #extract_hour, #extract_minute, #extract_month, #extract_month_name, #extract_quarter, #extract_week_of_year, #extract_year, #extract_year_month

Methods included from Functions::Dates

#adjust_week_start_day, #adjust_week_start_day?, #current_date, #current_time, #current_timestamp, #date_add, #date_data_type, #date_diff, #date_format, #date_format_sql, #date_int?, #date_lit, #date_literal, #date_time_format, #date_time_literal, #date_time_tz_format, #default_week_start_day, #timestamp_lit, #timestamp_literal, #week_start_day, #week_starts_on_sunday?

Methods included from Capabilities

#supports_array_functions?, #supports_common_table_expressions?, #supports_cross_join?, #supports_full_join?, #supports_sub_queries?, #supports_table_join?, #supports_temp_tables?, #supports_window_functions?

Constructor Details

This class inherits a constructor from DWH::Adapters::Adapter

Instance Method Details

#connection ⇒ Object

Creates a connection to the target database and returns the connection object or self



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# File 'lib/dwh/adapters/my_sql.rb', line 37

def connection
  return @connection if @connection

  set_default_ssl_mode_if_needed

  properties = {
    # Connection Settings
    host: config[:host],
    username: config[:username],
    password: config[:password],
    port: 3306,
    database: config[:database],

    # Timeout Settings
    connect_timeout: 10,
    read_timeout: config[:query_timeout],
    connect_attrs: {
      program: config[:client_name]
    }
  }.merge(extra_connection_params)

  @connection = Mysql2::Client.new(properties)
rescue StandardError => e
  raise ConfigError, e.message
end

#execute(sql, format: :array, retries: 0) ⇒ Array<Array>, ...

Execute sql on the target database.

Parameters:

  • sql (String) —

    actual sql

  • format (Symbol, String) (defaults to: :array) —

    return format type

    • array returns array of array
    • object returns array of Hashes
    • csv returns as csv
    • native returns the native result from any clients used
      • For example: Postgres using pg client will return PG::Result
      • Http clients will returns the HTTP response object
  • retries (Integer) (defaults to: 0) —

    number of retries in case of failure. Default is 0

Returns:

  • (Array<Array>, Hash, CSV, Native)

Raises:



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# File 'lib/dwh/adapters/my_sql.rb', line 134

def execute(sql, format: :array, retries: 0)
  begin
    as_param = %i[array object].include?(format) ? format : :array
    result = with_debug(sql) { with_retry(retries) { connection.query(sql, as: as_param) } }
  rescue StandardError => e
    raise ExecutionError, e.message
  end

  format = format.downcase if format.is_a?(String)
  case format.to_sym
  when :array, :object
    result.to_a
  when :csv
    result_to_csv(result)
  when :native
    result
  else
    raise UnsupportedCapability, "Unsupported format: #{format} for this #{name}"
  end
end

#execute_stream(sql, io, stats: nil, retries: 0) ⇒ IO

Execute sql and stream responses back. Data is writtent out in CSV format to the provided IO object.

Parameters:

  • sql (String) —

    actual sql

  • io (IO) —

    IO object to write records to

  • stats (StreamingStats) (defaults to: nil) —

    collect stats and preview data this is optional

  • retries (Integer) (defaults to: 0) —

    number of retries in case of failure

Returns:

  • (IO)

Raises:



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# File 'lib/dwh/adapters/my_sql.rb', line 156

def execute_stream(sql, io, stats: nil, retries: 0)
  with_debug(sql) do
    with_retry(retries) do
      result = connection.query(sql, stream: true, as: :array, cache_rows: false)
      io.write(CSV.generate_line(result.fields))
      result.each do |row|
        io.write(CSV.generate_line(row))
        stats << row if stats
      end
    end
  end

  io.rewind
  io
rescue StandardError => e
  raise ExecutionError, e.message
end

#metadata(table, **qualifiers) ⇒ DWH::Table

Get the schema structure of a given a given table_name. Pass in optional catalog and schema info.

Example: metadata("public.big_table") metadata("big_table") metadata("big_table",schema: "public")

Parameters:

  • table (String) —
    • table name
  • qualifiers (Hash) —

    a customizable set of options

Options Hash (**qualifiers):

  • :catalog (String) —

    optional catalog or equivalent name space. will be ignored if the adapter doesn't support

  • :schema (String) —

    optional schema to scope to. will be ignored if the adapter doesn't support

Returns:



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# File 'lib/dwh/adapters/my_sql.rb', line 108

def metadata(table, **qualifiers)
  db_table = Table.new table, schema: qualifiers[:schema]
  schema_where = db_table.schema ? " AND table_schema = '#{db_table.schema}'" : ''

  sql = <<-SQL
  SELECT column_name, data_type, character_maximum_length, numeric_precision,numeric_scale
  FROM information_schema.columns
  WHERE lower(table_name) = lower('#{db_table.physical_name}')
  #{schema_where}
  SQL

  cols = execute(sql, format: :object)
  cols.each do |col|
    db_table << Column.new(
      name: col['COLUMN_NAME'],
      data_type: col['DATA_TYPE'],
      precision: col['NUMERIC_PRECISION'],
      scale: col['NUMERIC_SCALE'],
      max_char_length: col['CHARACTER_MAXIMUM_LENGTH']
    )
  end

  db_table
end

#stats(table, date_column: nil, **qualifiers) ⇒ DWH::Table

Returns basic stats of a given table. Will typically include row_count, date_start, and date_end.

Examples:

stats("public.big_table", date_column: "fact_date")
stats("big_table")
stats("big_table",schema: "public")

Parameters:

  • table (String) —

    table name

  • date_column (String) (defaults to: nil) —

    optional date column to use to find range

  • qualifiers (Hash) —

    a customizable set of options

Options Hash (**qualifiers):

  • :catalog (String) —

    optional catalog or equivalent name space. will be ignored if the adapter doesn't support

  • :schema (String) —

    optional schema to scope to. will be ignored if the adapter doesn't support

Returns:

Raises:



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# File 'lib/dwh/adapters/my_sql.rb', line 89

def stats(table, date_column: nil, **qualifiers)
  table = "#{qualifiers[:schema]}.#{table}" if qualifiers[:schema]
  sql = <<-SQL
              SELECT count(*) row_count
                  #{date_column.nil? ? nil : ", min(#{date_column}) date_start"}
                  #{date_column.nil? ? nil : ", max(#{date_column}) date_end"}
              FROM #{table}
  SQL

  result = connection.query(sql)

  TableStats.new(
    row_count: result.first['row_count'],
    date_start: result.first['date_start'],
    date_end: result.first['date_end']
  )
end

#stream(sql) {|chunk| ... } ⇒ Object

Executes the given sql and yields the streamed results to the given block.

Parameters:

  • sql (String) —

    actual sql

Yields:

  • (chunk) —

    Yields a streamed chunk as it streams in. The chunk type might vary depending on the target db and settings

Raises:



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# File 'lib/dwh/adapters/my_sql.rb', line 175

def stream(sql, &block)
  with_debug(sql) do
    result = connection.query(sql, as: :array, cache_rows: false)
    result.each do |row|
      block.call(row)
    end
  end
end

#tables(**qualifiers) ⇒ Array<String>

Get all tables available in the target db. It will use the default catalog and schema config only specified here.

Parameters:

  • qualifiers (Hash) —

    a customizable set of options

Options Hash (**qualifiers):

  • :catalog (String) —

    optional catalog or equivalent name space. will be ignored if the adapter doesn't support

  • :schema (String) —

    optional schema to scope to. will be ignored if the adapter doesn't support

Returns:

  • (Array<String>) 


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# File 'lib/dwh/adapters/my_sql.rb', line 74

def tables(**qualifiers)
  schema = qualifiers[:schema] || config[:database]
  query = "
            SELECT
              t.table_name
            FROM information_schema.tables t
            WHERE t.table_schema = '#{schema}'
            ORDER BY t.table_name
  "

  res = connection.query(query, as: :array)
  res.to_a.flatten
end

#test_connection(raise_exception: false) ⇒ Boolean

Tests the connection to the target database and returns true if successful, or raise Exception or false connection object or self

Returns:

Raises:



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# File 'lib/dwh/adapters/my_sql.rb', line 64

def test_connection(raise_exception: false)
  connection
  true
rescue StandardError => e
  raise ConnectionError, e.message if raise_exception

  false
end

#truncate_date(unit, exp) ⇒ Object

Custom date truncation implementation. MySql doesn't offer a native function. We basially have to format it and convert back to date object.

See Also:



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# File 'lib/dwh/adapters/my_sql.rb', line 188

def truncate_date(unit, exp)
  unit = unit.strip.downcase

  case unit
  when 'year'
    "DATE(DATE_FORMAT(#{exp}, '%Y-01-01'))"
  when 'quarter'
    "DATE(DATE_ADD(DATE_FORMAT(#{exp}, '%Y-01-01'), INTERVAL (QUARTER(#{exp}) - 1) * 3 MONTH))"
  when 'month'
    "DATE(DATE_FORMAT(#{exp}, '%Y-%m-01'))"
  when 'week'
    gsk("#{settings[:week_start_day].downcase}_week_start_day")
      .gsub(/@exp/i, exp)
  when 'day', 'date'
    "DATE(#{exp})"
  when 'hour'
    "TIMESTAMP(DATE_FORMAT(#{exp}, '%Y-%m-%d %H:00:00'))"
  else
    raise UnsupportedCapability, "Currently not supporting truncation at #{unit} level"
  end
end