Class: PgDog

Inherits:
Object
  • Object
show all
Defined in:
lib/pgdog.rb

Class Method Summary collapse

Class Method Details

.check_transaction ⇒ Object

Ensure a transaction isn’t started already.



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# File 'lib/pgdog.rb', line 63

def self.check_transaction
  if ActiveRecord::Base.connection.open_transactions != 0
    raise PgDogError, "Transaction already started, can't set route"
  end
end

.connection ⇒ Object

Get a connection from ActiveRecord.



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# File 'lib/pgdog.rb', line 3

def self.connection
  return ActiveRecord::Base.connection
end

.shard ⇒ Object

Get currently set shard, if any.



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# File 'lib/pgdog.rb', line 45

def self.shard
  shard = self.connection.execute "SELECT current_setting('pgdog.shard', true)"
  shard = shard[0]["current_setting"]

  if shard.nil?
    return nil
  else
    return shard.to_i
  end
end

.sharding_key ⇒ Object

Get currently set sharding key, if any.



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# File 'lib/pgdog.rb', line 57

def self.sharding_key
  key = self.connection.execute "SELECT current_setting('pgdog.sharding_key', true)"
  key[0]["current_setting"]
end

.shards ⇒ Object

Get the number of configured shards

Can only work outside of a transaction, because a started transaction is most likely already routed to a shard and the PgDog query parser won’t be used.



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# File 'lib/pgdog.rb', line 38

def self.shards
  PgDog.check_transaction
  shards = self.connection.execute "SHOW \"pgdog.shards\""
  return shards[0]["shards"].to_i
end

.with_shard(shard) ⇒ Object

Start a transaction and set the shard number manually using SET.



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# File 'lib/pgdog.rb', line 9

def self.with_shard(shard)
  # Basic SQL injection protection
  shard = shard.to_i

  PgDog.check_transaction
  ActiveRecord::Base.transaction do
    self.connection.execute "SET \"pgdog.shard\" TO #{shard}"
    yield
  end
end

.with_sharding_key(key) ⇒ Object

Start a transaction and set the sharding key manually using SET.



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# File 'lib/pgdog.rb', line 22

def self.with_sharding_key(key)
  # Basic SQL injection protection.
  key = key.to_s.sub "'", "''"

  PgDog.check_transaction
  ActiveRecord::Base.transaction do
    self.connection.execute "SET \"pgdog.sharding_key\" TO '#{key}'"
    yield
  end
end