Class: NoSE::Backend::Backend

Inherits:
Object
  • Object
show all
Includes:
Listing, Supertype
Defined in:
lib/nose/backend.rb

Overview

Superclass of all database backends

Direct Known Subclasses

CassandraBackend, FileBackend, MongoBackend

Defined Under Namespace

Classes: DeleteStatementStep, FilterStatementStep, IndexLookupStatementStep, InsertStatementStep, LimitStatementStep, SortStatementStep, StatementStep

Instance Method Summary collapse

Methods included from Supertype

included

Methods included from Listing

included

Constructor Details

#initialize(model, indexes, plans, update_plans, _config) ⇒ Backend

Returns a new instance of Backend.



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# File 'lib/nose/backend.rb', line 11

def initialize(model, indexes, plans, update_plans, _config)
  @model = model
  @indexes = indexes
  @plans = plans
  @update_plans = update_plans
end

Instance Method Details

#by_id_graph ⇒ Boolean

By default, do not use ID graphs

Returns:

  • (Boolean) 


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# File 'lib/nose/backend.rb', line 20

def by_id_graph
  false
end

#drop_index ⇒ void

This method is abstract.

Subclasses implement to remove existing indexes

This method returns an undefined value.



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# File 'lib/nose/backend.rb', line 38

def drop_index
end

#generate_id ⇒ Object

This method is abstract.

Subclasses implement to generate a new random ID

:nocov:

Returns:



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# File 'lib/nose/backend.rb', line 53

def generate_id
  fail NotImplementedError
end

#index_empty?(_index) ⇒ Boolean

This method is abstract.

Subclasses implement to check if an index is empty

Returns:

  • (Boolean) 


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# File 'lib/nose/backend.rb', line 26

def index_empty?(_index)
  true
end

#index_exists?(_index) ⇒ Boolean

This method is abstract.

Subclasses implement to check if an index already exists

Returns:

  • (Boolean) 


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# File 'lib/nose/backend.rb', line 32

def index_exists?(_index)
  false
end

#index_insert_chunk(_index, _chunk) ⇒ void

This method is abstract.

Subclasses implement to allow inserting data into the backend database

This method returns an undefined value.

:nocov:



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# File 'lib/nose/backend.rb', line 45

def index_insert_chunk(_index, _chunk)
  fail NotImplementedError
end

#indexes_ddl(_execute = false, _skip_existing = false, _drop_existing = false) ⇒ Enumerable

This method is abstract.

Subclasses should create indexes

:nocov:

Returns:



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# File 'lib/nose/backend.rb', line 61

def indexes_ddl(_execute = false, _skip_existing = false,
                _drop_existing = false)
  fail NotImplementedError
end

#indexes_sample(_index, _count) ⇒ Array<Hash>

This method is abstract.

Subclasses should return sample values from the index

:nocov:

Returns:



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# File 'lib/nose/backend.rb', line 70

def indexes_sample(_index, _count)
  fail NotImplementedError
end

#prepare(statement, plans = []) ⇒ Object

Prepare a statement to be executed with the given plans



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# File 'lib/nose/backend.rb', line 87

def prepare(statement, plans = [])
  if statement.is_a? Query
    prepare_query statement, statement.all_fields,
                  statement.conditions, plans
  elsif statement.is_a? Delete
    prepare_update statement, plans
  elsif statement.is_a? Disconnect
    prepare_update statement, plans
  elsif statement.is_a? Connection
    prepare_update statement, plans
  else
    prepare_update statement, plans
  end
end

#prepare_query(query, fields, conditions, plans = []) ⇒ PreparedQuery

Prepare a query to be executed with the given plans

Returns:



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# File 'lib/nose/backend.rb', line 77

def prepare_query(query, fields, conditions, plans = [])
  plan = plans.empty? ? find_query_plan(query) : plans.first

  state = Plans::QueryState.new(query, @model) unless query.nil?
  first_step = Plans::RootPlanStep.new state
  steps = [first_step] + plan.to_a + [nil]
  PreparedQuery.new query, prepare_query_steps(steps, fields, conditions)
end

#prepare_update(update, plans) ⇒ PreparedUpdate

Prepare an update for execution

Returns:



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# File 'lib/nose/backend.rb', line 111

def prepare_update(update, plans)
  # Search for plans if they were not given
  plans = find_update_plans(update) if plans.empty?
  fail PlanNotFound if plans.empty?

  # Prepare each plan
  plans.map do |plan|
    delete = false
    insert = false
    plan.update_steps.each do |step|
      delete = true if step.is_a?(Plans::DeletePlanStep)
      insert = true if step.is_a?(Plans::InsertPlanStep)
    end

    steps = []
    add_delete_step(plan, steps) if delete
    add_insert_step(plan, steps, plan.update_fields) if insert

    PreparedUpdate.new update, prepare_support_plans(plan), steps
  end
end

#query(query, plans = []) ⇒ Array<Hash>

Execute a query with the stored plans

Returns:



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# File 'lib/nose/backend.rb', line 104

def query(query, plans = [])
  prepared = prepare query, plans
  prepared.execute query.conditions
end

#update(update, plans = []) ⇒ void

This method returns an undefined value.

Execute an update with the stored plans



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# File 'lib/nose/backend.rb', line 135

def update(update, plans = [])
  prepared = prepare_update update, plans
  prepared.each { |p| p.execute update.settings, update.conditions }
end