Class: Google::Cloud::Spanner::Snapshot

Inherits:
Object
  • Object
show all
Defined in:
lib/google/cloud/spanner/snapshot.rb

Overview

Snapshot

A snapshot in Cloud Spanner is a set of reads that execute atomically at a single logical point in time across columns, rows, and tables in a database.

Examples:

require "google/cloud/spanner"

spanner = Google::Cloud::Spanner.new
db = spanner.client "my-instance", "my-database"

db.snapshot do |snp|
  results = snp.execute_query "SELECT * FROM users"

  results.rows.each do |row|
    puts "User #{row[:id]} is #{row[:name]}"
  end
end

Instance Method Summary collapse

Instance Method Details

#execute_query(sql, params: nil, types: nil, query_options: nil, call_options: nil) ⇒ Google::Cloud::Spanner::Results Also known as: execute, query, execute_sql

Executes a SQL query.

Examples:

require "google/cloud/spanner"

spanner = Google::Cloud::Spanner.new
db = spanner.client "my-instance", "my-database"

db.snapshot do |snp|
  results = snp.execute_query "SELECT * FROM users"

  results.rows.each do |row|
    puts "User #{row[:id]} is #{row[:name]}"
  end
end

Query using query parameters:

require "google/cloud/spanner"

spanner = Google::Cloud::Spanner.new
db = spanner.client "my-instance", "my-database"

db.snapshot do |snp|
  results = snp.execute_query "SELECT * FROM users " \
                        "WHERE active = @active",
                        params: { active: true }

  results.rows.each do |row|
    puts "User #{row[:id]} is #{row[:name]}"
  end
end

Query with a SQL STRUCT query parameter as a Hash:

require "google/cloud/spanner"

spanner = Google::Cloud::Spanner.new
db = spanner.client "my-instance", "my-database"

db.snapshot do |snp|
   user_hash = { id: 1, name: "Charlie", active: false }

  results = snp.execute_query(
    "SELECT * FROM users WHERE " \
    "ID = @user_struct.id " \
    "AND name = @user_struct.name " \
    "AND active = @user_struct.active",
    params: { user_struct: user_hash }
  )

  results.rows.each do |row|
    puts "User #{row[:id]} is #{row[:name]}"
  end
end

Specify the SQL STRUCT type using Fields object:

require "google/cloud/spanner"

spanner = Google::Cloud::Spanner.new
db = spanner.client "my-instance", "my-database"

db.snapshot do |snp|
   user_type = snp.fields id: :INT64, name: :STRING, active: :BOOL
   user_hash = { id: 1, name: nil, active: false }

  results = snp.execute_query(
    "SELECT * FROM users WHERE " \
    "ID = @user_struct.id " \
    "AND name = @user_struct.name " \
    "AND active = @user_struct.active",
    params: { user_struct: user_hash },
    types: { user_struct: user_type }
  )

  results.rows.each do |row|
    puts "User #{row[:id]} is #{row[:name]}"
  end
end

Or, query with a SQL STRUCT as a typed Data object:

require "google/cloud/spanner"

spanner = Google::Cloud::Spanner.new
db = spanner.client "my-instance", "my-database"

db.snapshot do |snp|
   user_type = snp.fields id: :INT64, name: :STRING, active: :BOOL
user_data = user_type.struct id: 1, name: nil, active: false

  results = snp.execute_query(
    "SELECT * FROM users WHERE " \
    "ID = @user_struct.id " \
    "AND name = @user_struct.name " \
    "AND active = @user_struct.active",
    params: { user_struct: user_data }
  )

  results.rows.each do |row|
    puts "User #{row[:id]} is #{row[:name]}"
  end
end

Query using query options:

require "google/cloud/spanner"

spanner = Google::Cloud::Spanner.new
db = spanner.client "my-instance", "my-database"

db.snapshot do |snp|
  results = snp.execute_query \
    "SELECT * FROM users", query_options: {
      optimizer_version: "1",
      optimizer_statistics_package: "auto_20191128_14_47_22UTC"
    }

  results.rows.each do |row|
    puts "User #{row[:id]} is #{row[:name]}"
  end
end

Query using custom timeout and retry policy:

require "google/cloud/spanner"

spanner = Google::Cloud::Spanner.new
db = spanner.client "my-instance", "my-database"

timeout = 30.0
retry_policy = {
  initial_delay: 0.25,
  max_delay:     32.0,
  multiplier:    1.3,
  retry_codes:   ["UNAVAILABLE"]
}
call_options = { timeout: timeout, retry_policy: retry_policy }

db.snapshot do |snp|
  results = snp.execute_query \
    "SELECT * FROM users", call_options: call_options

  results.rows.each do |row|
    puts "User #{row[:id]} is #{row[:name]}"
  end
end



290
291
292
293
294
295
296
297
298
299
 
# File 'lib/google/cloud/spanner/snapshot.rb', line 290

def execute_query sql, params: nil, types: nil, query_options: nil,
                  call_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: query_options,
                             call_options: call_options
end

#fields(types) ⇒ Fields

Creates a configuration object (Fields) that may be provided to queries or used to create STRUCT objects. (The STRUCT will be represented by the Data class.) See Client#execute and/or Fields#struct.

For more information, see Data Types - Constructing a STRUCT.

See Data Types - Constructing a STRUCT.

Examples:

Create a STRUCT value with named fields using Fields object:

require "google/cloud/spanner"

spanner = Google::Cloud::Spanner.new
db = spanner.client "my-instance", "my-database"

db.snapshot do |snp|
  named_type = snp.fields(
    { id: :INT64, name: :STRING, active: :BOOL }
  )
  named_data = named_type.struct(
    { id: 42, name: nil, active: false }
  )
end

Create a STRUCT value with anonymous field names:

require "google/cloud/spanner"

spanner = Google::Cloud::Spanner.new
db = spanner.client "my-instance", "my-database"

db.snapshot do |snp|
  anon_type = snp.fields [:INT64, :STRING, :BOOL]
  anon_data = anon_type.struct [42, nil, false]
end

Create a STRUCT value with duplicate field names:

require "google/cloud/spanner"

spanner = Google::Cloud::Spanner.new
db = spanner.client "my-instance", "my-database"

db.snapshot do |snp|
  dup_type = snp.fields [[:x, :INT64], [:x, :STRING], [:x, :BOOL]]
  dup_data = dup_type.struct [42, nil, false]
end



438
439
440
 
# File 'lib/google/cloud/spanner/snapshot.rb', line 438

def fields types
  Fields.new types
end

#range(beginning, ending, exclude_begin: false, exclude_end: false) ⇒ Google::Cloud::Spanner::Range

Creates a Cloud Spanner Range. This can be used in place of a Ruby Range when needing to exclude the beginning value.

Examples:

require "google/cloud/spanner"

spanner = Google::Cloud::Spanner.new
db = spanner.client "my-instance", "my-database"

db.snapshot do |snp|
  key_range = db.range 1, 100
  results = snp.read "users", [:id, :name], keys: key_range

  results.rows.each do |row|
    puts "User #{row[:id]} is #{row[:name]}"
  end
end



471
472
473
474
475
 
# File 'lib/google/cloud/spanner/snapshot.rb', line 471

def range beginning, ending, exclude_begin: false, exclude_end: false
  Range.new beginning, ending,
            exclude_begin: exclude_begin,
            exclude_end: exclude_end
end

#read(table, columns, keys: nil, index: nil, limit: nil, call_options: nil) ⇒ Google::Cloud::Spanner::Results

Read rows from a database table, as a simple alternative to #execute_query.

Examples:

require "google/cloud/spanner"

spanner = Google::Cloud::Spanner.new
db = spanner.client "my-instance", "my-database"

db.snapshot do |snp|
  results = snp.read "users", [:id, :name]

  results.rows.each do |row|
    puts "User #{row[:id]} is #{row[:name]}"
  end
end



351
352
353
354
355
356
357
358
359
360
361
 
# File 'lib/google/cloud/spanner/snapshot.rb', line 351

def read table, columns, keys: nil, index: nil, limit: nil,
         call_options: 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,
                               call_options: call_options
end

#timestamp ⇒ Time

The read timestamp chosen for snapshots.



58
59
60
61
 
# File 'lib/google/cloud/spanner/snapshot.rb', line 58

def timestamp
  return nil if @grpc.nil?
  Convert.timestamp_to_time @grpc.read_timestamp
end

#transaction_id ⇒ String

Identifier of the transaction results were run in.



50
51
52
53
 
# File 'lib/google/cloud/spanner/snapshot.rb', line 50

def transaction_id
  return nil if @grpc.nil?
  @grpc.id
end