docs(spanner): snippet for setting read lock mode (#1473)

docs(spanner): snippet for setting read lock mode (#1473) · googleapis/python-spanner@7e79920

@@ -3186,14 +3186,13 @@ def isolation_level_options(

31863186instance_id,31873187database_id,31883188):3189-from google.cloud.spanner_v1 import TransactionOptions, DefaultTransactionOptions3190-31913189"""31923190 Shows how to run a Read Write transaction with isolation level options.31933191 """31943192# [START spanner_isolation_level]31953193# instance_id = "your-spanner-instance"31963194# database_id = "your-spanner-db-id"3195+from google.cloud.spanner_v1 import TransactionOptions, DefaultTransactionOptions3197319631983197# The isolation level specified at the client-level will be applied to all RW transactions.31993198isolation_options_for_client = TransactionOptions.IsolationLevel.SERIALIZABLE

@@ -3232,6 +3231,60 @@ def update_albums_with_isolation(transaction):

32323231# [END spanner_isolation_level]32333232323432333234+def read_lock_mode_options(3235+instance_id,3236+database_id,3237+):3238+"""3239+ Shows how to run a Read Write transaction with read lock mode options.3240+ """3241+# [START spanner_read_lock_mode]3242+# instance_id = "your-spanner-instance"3243+# database_id = "your-spanner-db-id"3244+from google.cloud.spanner_v1 import TransactionOptions, DefaultTransactionOptions3245+3246+# The read lock mode specified at the client-level will be applied to all3247+# RW transactions.3248+read_lock_mode_options_for_client = TransactionOptions.ReadWrite.ReadLockMode.OPTIMISTIC3249+3250+# Create a client that uses Serializable isolation (default) with3251+# optimistic locking for read-write transactions.3252+spanner_client = spanner.Client(3253+default_transaction_options=DefaultTransactionOptions(3254+read_lock_mode=read_lock_mode_options_for_client3255+ )3256+ )3257+instance = spanner_client.instance(instance_id)3258+database = instance.database(database_id)3259+3260+# The read lock mode specified at the request level takes precedence over3261+# the read lock mode configured at the client level.3262+read_lock_mode_options_for_transaction = (3263+TransactionOptions.ReadWrite.ReadLockMode.PESSIMISTIC3264+ )3265+3266+def update_albums_with_read_lock_mode(transaction):3267+# Read an AlbumTitle.3268+results = transaction.execute_sql(3269+"SELECT AlbumTitle from Albums WHERE SingerId = 2 and AlbumId = 1"3270+ )3271+for result in results:3272+print("Current Album Title: {}".format(*result))3273+3274+# Update the AlbumTitle.3275+row_ct = transaction.execute_update(3276+"UPDATE Albums SET AlbumTitle = 'A New Title' WHERE SingerId = 2 and AlbumId = 1"3277+ )3278+3279+print("{} record(s) updated.".format(row_ct))3280+3281+database.run_in_transaction(3282+update_albums_with_read_lock_mode,3283+read_lock_mode=read_lock_mode_options_for_transaction3284+ )3285+# [END spanner_read_lock_mode]3286+3287+32353288def set_custom_timeout_and_retry(instance_id, database_id):32363289"""Executes a snapshot read with custom timeout and retry."""32373290# [START spanner_set_custom_timeout_and_retry]

@@ -3856,6 +3909,9 @@ def add_split_points(instance_id, database_id):

38563909subparsers.add_parser(38573910"isolation_level_options", help=isolation_level_options.__doc__38583911 )3912+subparsers.add_parser(3913+"read_lock_mode_options", help=read_lock_mode_options.__doc__3914+ )38593915subparsers.add_parser(38603916"set_custom_timeout_and_retry", help=set_custom_timeout_and_retry.__doc__38613917 )

@@ -4018,6 +4074,8 @@ def add_split_points(instance_id, database_id):

40184074directed_read_options(args.instance_id, args.database_id)40194075elif args.command == "isolation_level_options":40204076isolation_level_options(args.instance_id, args.database_id)4077+elif args.command == "read_lock_mode_options":4078+read_lock_mode_options(args.instance_id, args.database_id)40214079elif args.command == "set_custom_timeout_and_retry":40224080set_custom_timeout_and_retry(args.instance_id, args.database_id)40234081elif args.command == "create_instance_with_autoscaling_config":