Class: Google::Cloud::Spanner::BatchSnapshot
- Inherits:
-
Object
- Object
- Google::Cloud::Spanner::BatchSnapshot
- Defined in:
- lib/google/cloud/spanner/batch_snapshot.rb
Overview
BatchSnapshot
Represents a read-only transaction that can be configured to read at timestamps in the past and allows for exporting arbitrarily large amounts of data from Cloud Spanner databases. This is a snapshot which additionally allows to partition a read or query request. The read/query request can then be executed independently over each partition while observing the same snapshot of the database. A BatchSnapshot can also be shared across multiple processes/machines by passing around its serialized value and then recreating the transaction using #dump.
Unlike locking read-write transactions, BatchSnapshot will never abort. They can fail if the chosen read timestamp is garbage collected; however any read or query activity within an hour on the transaction avoids garbage collection and most applications do not need to worry about this in practice.
See Google::Cloud::Spanner::BatchClient#batch_snapshot and Google::Cloud::Spanner::BatchClient#load_batch_snapshot.
Instance Method Summary collapse
-
#close ⇒ Object
Closes the batch snapshot and releases the underlying resources.
-
#dump ⇒ String
(also: #serialize)
Serializes the batch snapshot object so it can be recreated on another process.
-
#execute_partition(partition) ⇒ Object
Execute the partition to return a Results.
-
#execute_query(sql, params: nil, types: nil, query_options: nil) ⇒ Google::Cloud::Spanner::Results
(also: #execute, #query, #execute_sql)
Executes a SQL query.
-
#partition_query(sql, params: nil, types: nil, partition_size_bytes: nil, max_partitions: nil, query_options: nil) ⇒ Array<Google::Cloud::Spanner::Partition>
Returns a list of Partition objects to execute a batch query against a database.
-
#partition_read(table, columns, keys: nil, index: nil, partition_size_bytes: nil, max_partitions: nil) ⇒ Array<Google::Cloud::Spanner::Partition>
Returns a list of Partition objects to read zero or more rows from a database.
-
#read(table, columns, keys: nil, index: nil, limit: nil) ⇒ Google::Cloud::Spanner::Results
Read rows from a database table, as a simple alternative to #execute_query.
-
#timestamp ⇒ Time
The read timestamp chosen for batch snapshot.
-
#transaction_id ⇒ String
Identifier of the batch snapshot transaction.
Instance Method Details
#close ⇒ Object
Closes the batch snapshot and releases the underlying resources.
This should only be called once the batch snapshot is no longer needed anywhere. In particular if this batch snapshot is being used across multiple machines, calling this method on any of the machines will render the batch snapshot invalid everywhere.
362 363 364 365 366 |
# File 'lib/google/cloud/spanner/batch_snapshot.rb', line 362 def close ensure_session! session.release! end |
#dump ⇒ String Also known as: serialize
Serializes the batch snapshot object so it can be recreated on another process. See Google::Cloud::Spanner::BatchClient#load_batch_snapshot.
655 656 657 |
# File 'lib/google/cloud/spanner/batch_snapshot.rb', line 655 def dump JSON.dump to_h end |
#execute_partition(partition) ⇒ Object
Execute the partition to return a Results. The result returned could be zero or more rows. The row metadata may be absent if no rows are returned.
323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 |
# File 'lib/google/cloud/spanner/batch_snapshot.rb', line 323 def execute_partition partition ensure_session! partition = Partition.load partition unless partition.is_a? Partition # TODO: raise if partition.empty? # TODO: raise if session.path != partition.session # TODO: raise if grpc.transaction != partition.transaction if partition.execute? execute_partition_query partition elsif partition.read? execute_partition_read partition end end |
#execute_query(sql, params: nil, types: nil, query_options: nil) ⇒ Google::Cloud::Spanner::Results Also known as: execute, query, execute_sql
Executes a SQL query.
552 553 554 555 556 557 558 559 560 |
# File 'lib/google/cloud/spanner/batch_snapshot.rb', line 552 def execute_query sql, params: nil, types: nil, query_options: nil ensure_session! params, types = Convert.to_input_params_and_types params, types session.execute_query sql, params: params, types: types, transaction: tx_selector, query_options: end |
#partition_query(sql, params: nil, types: nil, partition_size_bytes: nil, max_partitions: nil, query_options: nil) ⇒ Array<Google::Cloud::Spanner::Partition>
Returns a list of Partition objects to execute a batch query against a database.
These partitions can be executed across multiple processes, even across different machines. The partition size and count can be configured, although the values given may not necessarily be honored depending on the query and options in the request.
The query must have a single distributed union operator at the root of the query plan. Such queries are root-partitionable. If a query cannot be partitioned at the root, Cloud Spanner cannot achieve the parallelism and in this case partition generation will fail.
197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 |
# File 'lib/google/cloud/spanner/batch_snapshot.rb', line 197 def partition_query sql, params: nil, types: nil, partition_size_bytes: nil, max_partitions: nil, query_options: nil ensure_session! params, types = Convert.to_input_params_and_types params, types results = session.partition_query \ sql, tx_selector, params: params, types: types, partition_size_bytes: partition_size_bytes, max_partitions: max_partitions results.partitions.map do |grpc| # Convert partition protos to execute sql request protos execute_sql_grpc = Google::Spanner::V1::ExecuteSqlRequest.new( { session: session.path, sql: sql, params: params, param_types: types, transaction: tx_selector, partition_token: grpc.partition_token, query_options: }.delete_if { |_, v| v.nil? } ) Partition.from_execute_sql_grpc execute_sql_grpc end end |
#partition_read(table, columns, keys: nil, index: nil, partition_size_bytes: nil, max_partitions: nil) ⇒ Array<Google::Cloud::Spanner::Partition>
Returns a list of Partition objects to read zero or more rows from a database.
These partitions can be executed across multiple processes, even across different machines. The partition size and count can be configured, although the values given may not necessarily be honored depending on the query and options in the request.
270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 |
# File 'lib/google/cloud/spanner/batch_snapshot.rb', line 270 def partition_read table, columns, keys: nil, index: nil, partition_size_bytes: nil, max_partitions: nil ensure_session! columns = Array(columns).map(&:to_s) keys = Convert.to_key_set keys results = session.partition_read \ table, columns, tx_selector, keys: keys, index: index, partition_size_bytes: partition_size_bytes, max_partitions: max_partitions results.partitions.map do |grpc| # Convert partition protos to read request protos read_grpc = Google::Spanner::V1::ReadRequest.new( { session: session.path, table: table, columns: columns, key_set: keys, index: index, transaction: tx_selector, partition_token: grpc.partition_token }.delete_if { |_, v| v.nil? } ) Partition.from_read_grpc read_grpc end end |
#read(table, columns, keys: nil, index: nil, limit: nil) ⇒ Google::Cloud::Spanner::Results
Read rows from a database table, as a simple alternative to #execute_query.
598 599 600 601 602 603 604 605 606 |
# File 'lib/google/cloud/spanner/batch_snapshot.rb', line 598 def read table, columns, keys: nil, index: nil, limit: nil ensure_session! columns = Array(columns).map(&:to_s) keys = Convert.to_key_set keys session.read table, columns, keys: keys, index: index, limit: limit, transaction: tx_selector end |
#timestamp ⇒ Time
The read timestamp chosen for batch snapshot.
86 87 88 89 |
# File 'lib/google/cloud/spanner/batch_snapshot.rb', line 86 def return nil if grpc.nil? Convert. grpc. end |
#transaction_id ⇒ String
Identifier of the batch snapshot transaction.
78 79 80 81 |
# File 'lib/google/cloud/spanner/batch_snapshot.rb', line 78 def transaction_id return nil if grpc.nil? grpc.id end |