module Sequel::Plugins::PagedOperations::DatasetMethods
Public Instance Methods
Yield datasets for subsets of the receiver that are limited to no more than 1000 rows (you can configure the number of rows using :rows_per_page
).
Options:
- :rows_per_page
-
The maximum number of rows in each yielded dataset (unless concurrent modifications are made to the table).
# File lib/sequel/plugins/paged_operations.rb 91 def paged_datasets(opts=OPTS) 92 unless defined?(yield) 93 return enum_for(:paged_datasets, opts) 94 end 95 96 pk = _paged_operations_pk(:paged_update) 97 base_offset_ds = offset_ds = _paged_operations_offset_ds(opts) 98 first = nil 99 100 while last = offset_ds.get(pk) 101 ds = where(pk < last) 102 ds = ds.where(pk >= first) if first 103 yield ds 104 first = last 105 offset_ds = base_offset_ds.where(pk >= first) 106 end 107 108 ds = self 109 ds = ds.where(pk >= first) if first 110 yield ds 111 nil 112 end
Delete all rows of the dataset using using multiple queries so that no more than 1000 rows are deleted at a time (you can configure the number of rows using :rows_per_page
).
Options:
- :rows_per_page
-
The maximum number of rows affected by each DELETE query (unless concurrent modifications are made to the table).
# File lib/sequel/plugins/paged_operations.rb 121 def paged_delete(opts=OPTS) 122 if (db.database_type == :oracle && !supports_fetch_next_rows?) || (db.database_type == :mssql && !is_2012_or_later?) 123 raise Error, "paged_delete is not supported on MSSQL/Oracle when using emulated offsets" 124 end 125 pk = _paged_operations_pk(:paged_delete) 126 rows_deleted = 0 127 offset_ds = _paged_operations_offset_ds(opts) 128 while last = offset_ds.get(pk) 129 rows_deleted += where(pk < last).delete 130 end 131 rows_deleted + delete 132 end
Update all rows of the dataset using using multiple queries so that no more than 1000 rows are updated at a time (you can configure the number of rows using :rows_per_page
). All arguments are passed to Dataset#update
.
Options:
- :rows_per_page
-
The maximum number of rows affected by each UPDATE query (unless concurrent modifications are made to the table).
# File lib/sequel/plugins/paged_operations.rb 142 def paged_update(values, opts=OPTS) 143 rows_updated = 0 144 paged_datasets(opts) do |ds| 145 rows_updated += ds.update(values) 146 end 147 rows_updated 148 end
Private Instance Methods
The dataset that will be used by paged_{datasets,delete,update} to get the upper limit for the next query.
# File lib/sequel/plugins/paged_operations.rb 172 def _paged_operations_offset_ds(opts) 173 if rows_per_page = opts[:rows_per_page] 174 raise Error, ":rows_per_page option must be at least 1" unless rows_per_page >= 1 175 end 176 _force_primary_key_order.offset(rows_per_page || 1000) 177 end
Run some basic checks common to paged_{datasets,delete,update} and return the primary key to operate on as a Sequel::Identifier.
# File lib/sequel/plugins/paged_operations.rb 154 def _paged_operations_pk(meth) 155 raise Error, "cannot use #{meth} if dataset has a limit or offset" if @opts[:limit] || @opts[:offset] 156 if db.database_type == :db2 && db.offset_strategy == :emulate 157 raise Error, "the paged_operations plugin is not supported on DB2 when using emulated offsets, set the :offset_strategy Database option to 'limit_offset' or 'offset_fetch'" 158 end 159 160 case pk = model.primary_key 161 when Symbol 162 Sequel.identifier(pk) 163 when Array 164 raise Error, "cannot use #{meth} on a model with a composite primary key" 165 else 166 raise Error, "cannot use #{meth} on a model without a primary key" 167 end 168 end