Module: Gcloud::Bigquery
- Defined in:
- lib/gcloud/bigquery.rb,
lib/gcloud/bigquery/job.rb,
lib/gcloud/bigquery/data.rb,
lib/gcloud/bigquery/view.rb,
lib/gcloud/bigquery/table.rb,
lib/gcloud/bigquery/errors.rb,
lib/gcloud/bigquery/dataset.rb,
lib/gcloud/bigquery/project.rb,
lib/gcloud/bigquery/copy_job.rb,
lib/gcloud/bigquery/job/list.rb,
lib/gcloud/bigquery/load_job.rb,
lib/gcloud/bigquery/query_job.rb,
lib/gcloud/bigquery/connection.rb,
lib/gcloud/bigquery/query_data.rb,
lib/gcloud/bigquery/table/list.rb,
lib/gcloud/bigquery/credentials.rb,
lib/gcloud/bigquery/extract_job.rb,
lib/gcloud/bigquery/dataset/list.rb,
lib/gcloud/bigquery/insert_response.rb
Overview
Google Cloud BigQuery
Google Cloud BigQuery enables super-fast, SQL-like queries against massive datasets, using the processing power of Google’s infrastructure. To learn more, read What is BigQuery?.
Gcloud’s goal is to provide an API that is familiar and comfortable to Rubyists. Authentication is handled by Gcloud#bigquery. You can provide the project and credential information to connect to the BigQuery service, or if you are running on Google Compute Engine this configuration is taken care of for you. You can read more about the options for connecting in the Authentication Guide.
To help you get started quickly, the first few examples below use a public dataset provided by Google. As soon as you have signed up to use BigQuery, and provided that you stay in the free tier for queries, you should be able to run these first examples without the need to set up billing or to load data (although we’ll show you how to do that too.)
Listing Datasets and Tables
A BigQuery project holds datasets, which in turn hold tables. Assuming that you have not yet created datasets or tables in your own project, let’s connect to Google’s publicdata project, and see what you find.
require "gcloud"
gcloud = Gcloud.new "publicdata"
bigquery = gcloud.bigquery
bigquery.datasets.count #=> 1
bigquery.datasets.first.dataset_id #=> "samples"
dataset = bigquery.datasets.first
tables = dataset.tables
tables.count #=> 7
tables.map &:table_id #=> [..., "shakespeare", "trigrams", "wikipedia"]
In addition listing all datasets and tables in the project, you can also retrieve individual datasets and tables by ID. Let’s look at the structure of the shakespeare table, which contains an entry for every word in every play written by Shakespeare.
require "gcloud"
gcloud = Gcloud.new "publicdata"
bigquery = gcloud.bigquery
dataset = bigquery.dataset "samples"
table = dataset.table "shakespeare"
table.headers #=> ["word", "word_count", "corpus", "corpus_date"]
table.rows_count #=> 164656
Now that you know the column names for the Shakespeare table, you can write and run a query.
Running queries
BigQuery offers both synchronous and asynchronous methods, as explained in Querying Data.
Synchronous queries
Let’s start with the simpler synchronous approach. Notice that this time you are connecting using your own default project. This is necessary for running a query, since queries need to be able to create tables to hold results.
require "gcloud"
gcloud = Gcloud.new
bigquery = gcloud.bigquery
sql = "SELECT TOP(word, 50) as word, COUNT(*) as count " +
"FROM publicdata:samples.shakespeare"
data = bigquery.query sql
data.count #=> 50
data.next? #=> false
data.first #=> {"word"=>"you", "count"=>42}
The TOP function shown above is just one of a variety of functions offered by BigQuery. See the Query Reference for a full listing.
Asynchronous queries
Because you probably should not block for most BigQuery operations, including querying as well as importing, exporting, and copying data, the BigQuery API enables you to manage longer-running jobs. In the asynchronous approach to running a query, an instance of Gcloud::Bigquery::QueryJob is returned, rather than an instance of Gcloud::Bigquery::QueryData.
require "gcloud"
gcloud = Gcloud.new
bigquery = gcloud.bigquery
sql = "SELECT TOP(word, 50) as word, COUNT(*) as count " +
"FROM publicdata:samples.shakespeare"
job = bigquery.query_job sql
loop do
break if job.done?
sleep 1
job.refresh!
end
if !job.failed?
job.query_results.each do |row|
puts row["word"]
end
end
Once you have determined that the job is done and has not failed, you can obtain an instance of Gcloud::Bigquery::QueryData by calling Gcloud::Bigquery::QueryJob#query_results. The query results for both of the above examples are stored in temporary tables with a lifetime of about 24 hours. See the final example below for a demonstration of how to store query results in a permanent table.
Creating Datasets and Tables
The first thing you need to do in a new BigQuery project is to create a Gcloud::Bigquery::Dataset. Datasets hold tables and control access to them.
require "gcloud/bigquery"
gcloud = Gcloud.new
bigquery = gcloud.bigquery
dataset = bigquery.create_dataset "my_dataset"
Now that you have a dataset, you can use it to create a table. Every table is defined by a schema that may contain nested and repeated fields. The example below shows a schema with a repeated record field named cities_lived. (For more information about nested and repeated fields, see Preparing Data for BigQuery.)
require "gcloud"
gcloud = Gcloud.new
bigquery = gcloud.bigquery
dataset = bigquery.dataset "my_dataset"
schema = {
"fields" => [
{
"name" => "first_name",
"type" => "STRING",
"mode" => "REQUIRED"
},
{
"name" => "cities_lived",
"type" => "RECORD",
"mode" => "REPEATED",
"fields" => [
{
"name" => "place",
"type" => "STRING",
"mode" => "REQUIRED"
},
{
"name" => "number_of_years",
"type" => "INTEGER",
"mode" => "REQUIRED"
}
]
}
]
}
table = dataset.create_table "people", schema: schema
Because of the repeated field in this schema, we cannot use the CSV format to load data into the table.
Loading records
In addition to CSV, data can be imported from files that are formatted as Newline-delimited JSON or Avro, or from a Google Cloud Datastore backup. It can also be “streamed” into BigQuery.
To follow along with these examples, you will need to set up billing on the Google Developers Console.
Streaming records
For situations in which you want new data to be available for querying as soon as possible, inserting individual records directly from your Ruby application is a great approach.
require "gcloud"
gcloud = Gcloud.new
bigquery = gcloud.bigquery
dataset = bigquery.dataset "my_dataset"
table = dataset.table "people"
rows = [
{
"first_name" => "Anna",
"cities_lived" => [
{
"place" => "Stockholm",
"number_of_years" => 2
}
]
},
{
"first_name" => "Bob",
"cities_lived" => [
{
"place" => "Seattle",
"number_of_years" => 5
},
{
"place" => "Austin",
"number_of_years" => 6
}
]
}
]
table.insert rows
There are some trade-offs involved with streaming, so be sure to read the discussion of data consistency in Streaming Data Into BigQuery.
Uploading a file
To follow along with this example, please download the names.zip archive from the U.S. Social Security Administration. Inside the archive you will find over 100 files containing baby name records since the year 1880. A PDF file also contained in the archive specifies the schema used below.
require "gcloud"
gcloud = Gcloud.new
bigquery = gcloud.bigquery
dataset = bigquery.dataset "my_dataset"
schema = {
"fields" => [
{
"name" => "name",
"type" => "STRING",
"mode" => "REQUIRED"
},
{
"name" => "sex",
"type" => "STRING",
"mode" => "REQUIRED"
},
{
"name" => "number",
"type" => "INTEGER",
"mode" => "REQUIRED"
}
]
}
table = dataset.create_table "baby_names", schema: schema
file = File.open "names/yob2014.txt"
load_job = table.load file, format: "csv"
Because the names data, although formatted as CSV, is distributed in files with a .txt extension, this example explicitly passes the format option in order to demonstrate how to handle such situations. Because CSV is the default format for load operations, the option is not actually necessary. For JSON saved with a .txt extension, however, it would be.
Exporting query results to Google Cloud Storage
The example below shows how to pass the table option with a query in order to store results in a permanent table. It also shows how to export the result data to a Google Cloud Storage file. In order to follow along, you will need to enable the Google Cloud Storage API in addition to setting up billing.
require "gcloud"
gcloud = Gcloud.new
bigquery = gcloud.bigquery
dataset = bigquery.dataset "my_dataset"
source_table = dataset.table "baby_names"
result_table = dataset.create_table "baby_names_results"
sql = "SELECT name, number as count " +
"FROM baby_names " +
"WHERE name CONTAINS 'Sam' " +
"ORDER BY count DESC"
query_job = dataset.query_job sql, table: result_table
loop do
break if query_job.done?
sleep 1
query_job.refresh!
end
if !query_job.failed?
storage = gcloud.storage
bucket_id = "bigquery-exports-#{SecureRandom.uuid}"
bucket = storage.create_bucket bucket_id
extract_url = "gs://#{bucket.id}/baby-names-sam.csv"
extract_job = result_table.extract extract_url
loop do
break if extract_job.done?
sleep 1
extract_job.refresh!
end
# Download to local filesystem
bucket.files.first.download "baby-names-sam.csv"
end
If a table you wish to export contains a large amount of data, you can pass a wildcard URI to export to multiple files (for sharding), or an array of URIs (for partitioning), or both. See Exporting Data From BigQuery for details.
Defined Under Namespace
Classes: ApiError, Connection, CopyJob, Credentials, Data, Dataset, Error, ExtractJob, InsertResponse, Job, LoadJob, Project, QueryData, QueryJob, Table, View