Module: PostgreSQLCursor::ActiveRecord::SqlCursor

Defined in:
lib/postgresql_cursor/active_record/sql_cursor.rb

Instance Method Summary collapse

Instance Method Details

#each_instance(options = {}, &block) ⇒ Object

Public: Like each_row, but returns an instantiated model object to the block

Paramaters: same as each_row

Example:

Post.each_instance { |post| post.process }

Returns the number of rows yielded to the block


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# File 'lib/postgresql_cursor/active_record/sql_cursor.rb', line 32

def each_instance(options={}, &block)
  options = {:connection => self.connection}.merge(options)
  all.each_instance(options, &block)
end

#each_instance_batch(options = {}, &block) ⇒ Object

Public: Like each_row_batch, but yields an array of instantiated model objects to the block

Parameters: same as each_row

Example:

Post.each_instance_batch { |batch| Post.process_batch(batch) }

Returns the number of rows yielded to the block


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# File 'lib/postgresql_cursor/active_record/sql_cursor.rb', line 101

def each_instance_batch(options={}, &block)
  options = {:connection => self.connection}.merge(options)
  all.each_instance_batch(options, &block)
end

#each_instance_batch_by_sql(sql, options = {}, &block) ⇒ Object

Public: Yields each batch up to block_size of rows as model instances to the given block

As this instantiates a model object, it is slower than each_row_batch_by_sql

Paramaters: see each_row_by_sql

Example:

Post.each_instance_batch_by_sql("select * from posts") do |batch|
  Post.process_batch(batch)
end
Post.each_instance_batch_by_sql("select * from posts").map do |batch|
  Post.transform_batch(batch)
end

Returns the number of rows yielded to the block


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# File 'lib/postgresql_cursor/active_record/sql_cursor.rb', line 144

def each_instance_batch_by_sql(sql, options={}, &block)
  options = {:connection => self.connection}.merge(options)
  cursor  = PostgreSQLCursor::Cursor.new(sql, options)
  return cursor.each_instance_batch(self, &block) if block_given?
  cursor.iterate_type(self).iterate_batched
end

#each_instance_by_sql(sql, options = {}, &block) ⇒ Object

Public: Returns each row as a model instance to the given block As this instantiates a model object, it is slower than each_row_by_sql

Paramaters: see each_row_by_sql

Example:

Post.each_instance_by_sql("select * from posts") { |post| post.process }
Post.each_instance_by_sql("select * from posts").count

Returns the number of rows yielded to the block


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# File 'lib/postgresql_cursor/active_record/sql_cursor.rb', line 70

def each_instance_by_sql(sql, options={}, &block)
  options = {:connection => self.connection}.merge(options)
  cursor  = PostgreSQLCursor::Cursor.new(sql, options)
  return cursor.each_instance(self, &block) if block_given?
  cursor.iterate_type(self)
end

#each_row(options = {}, &block) ⇒ Object Also known as: each_hash

Public: Executes the query, returning each row as a hash to the given block.

options - Hash to control

fraction: 0.1..1.0    - The cursor_tuple_fraction (default 1.0)
block_size: 1..n      - The number of rows to fetch per db block fetch
while: value          - Exits loop when block does not return this value.
until: value          - Exits loop when block returns this value.
with_hold: boolean    - Allows the query to remain open across commit points.

Example:

Post.each_row { |hash| Post.process(hash) }

Returns the number of rows yielded to the block


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# File 'lib/postgresql_cursor/active_record/sql_cursor.rb', line 18

def each_row(options={}, &block)
  options = {:connection => self.connection}.merge(options)
  all.each_row(options, &block)
end

#each_row_batch(options = {}, &block) ⇒ Object Also known as: each_hash_batch

Public: Executes the query, yielding an array of up to block_size rows where each row is a hash to the given block.

Parameters: same as each_row

Example:

Post.each_row_batch { |batch| Post.process_batch(batch) }

Returns the number of rows yielded to the block


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# File 'lib/postgresql_cursor/active_record/sql_cursor.rb', line 86

def each_row_batch(options={}, &block)
  options = {:connection => self.connection}.merge(options)
  all.each_row_batch(options, &block)
end

#each_row_batch_by_sql(sql, options = {}, &block) ⇒ Object Also known as: each_hash_batch_by_sql

Public: Yields each batch of up to block_size rows as an array of rows where each row as a hash to the given block

Parameters: see each_row_by_sql

Example:

Post.each_row_batch_by_sql("select * from posts") do |batch|
  Post.process_batch(batch)
end
Post.each_row_batch_by_sql("select * from posts").map do |batch|
  Post.transform_batch(batch)
end

Returns the number of rows yielded to the block


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# File 'lib/postgresql_cursor/active_record/sql_cursor.rb', line 120

def each_row_batch_by_sql(sql, options={}, &block)
  options = {:connection => self.connection}.merge(options)
  cursor  = PostgreSQLCursor::Cursor.new(sql, options)
  return cursor.each_row_batch(&block) if block_given?
  cursor.iterate_batched
end

#each_row_by_sql(sql, options = {}, &block) ⇒ Object Also known as: each_hash_by_sql

sql - Full SQL statement, variables interpolated options - Hash to control

fraction: 0.1..1.0    - The cursor_tuple_fraction (default 1.0)
block_size: 1..n      - The number of rows to fetch per db block fetch
while: value          - Exits loop when block does not return this value.
until: value          - Exits loop when block returns this value.
with_hold: boolean    - Allows the query to remain open across commit points.

Example:

Post.each_row_by_sql("select * from posts") { |hash| Post.process(hash) }
Post.each_row_by_sql("select * from posts").count

Returns the number of rows yielded to the block


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# File 'lib/postgresql_cursor/active_record/sql_cursor.rb', line 52

def each_row_by_sql(sql, options={}, &block)
  options = {:connection => self.connection}.merge(options)
  cursor  = PostgreSQLCursor::Cursor.new(sql, options)
  return cursor.each_row(&block) if block_given?
  cursor
end

#pluck_instances(*cols) ⇒ Object Also known as: pluck_instance

Returns an array of the given column names. Use if you need cursors and don't expect this to comsume too much memory. Values are instance types. Like ActiveRecord's pluck.


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# File 'lib/postgresql_cursor/active_record/sql_cursor.rb', line 161

def pluck_instances(*cols)
  options = cols.last.is_a?(Hash) ? cols.pop : {}
  all.each_instance(options).pluck(*cols)
end

#pluck_rows(*cols) ⇒ Object Also known as: pluck_row

Returns an array of the given column names. Use if you need cursors and don't expect this to comsume too much memory. Values are strings. Like ActiveRecord's pluck.


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# File 'lib/postgresql_cursor/active_record/sql_cursor.rb', line 153

def pluck_rows(*cols)
  options = cols.last.is_a?(Hash) ? cols.pop : {}
  all.each_row(options).pluck(*cols)
end