Contents

• treasuredata_fdw
  • Installation
  • Setup
  • Update version
  • Usage
  • Table Options
  • INSERT INTO statement
  • Prepare Linux development environment
  • Regression test

treasuredata_fdw

PostgreSQL Foreign Data Wrapper for Treasure Data

Installation

This FDW uses td-client-rust. So you need to install Rust first.

With PGXN client:

$ pgxn install treasuredata_fdw

From source:

$ git clone https://github.com/komamitsu/treasuredata_fdw.git $ cd treasuredata_fdw $ make && sudo make install

When building this FDW on macOS, you may fail to build due to missing OpenSSL header files (https://github.com/sfackler/rust-openssl/issues/255). The following commands would solve the error. export OPENSSL_INCLUDE_DIR=/usr/local/opt/openssl/include export DEP_OPENSSL_INCLUDE=/usr/local/opt/openssl/include

Setup

Connect to your PostgreSQL and create an extension and foreign server

``` CREATE EXTENSION treasuredata_fdw;

CREATE SERVER treasuredata_server FOREIGN DATA WRAPPER treasuredata_fdw; ```

Update version

To update an existing treasuredata_fdw installation from versions earlier than 1.2 you can take the following steps:

• Download and install treasuredata_fdw version 1.2 using instructions from the "Instllation" section
• Restart the PostgreSQL server
• Run

ALTER EXTENSION treasuredata_fdw UPDATE;

Usage

Specify your API key, database, query engine type ('presto' or 'hive') in CREATE FOREIGN TABLE statement. You can specify either your table name or query for Treasure Data directly.

``` CREATE FOREIGN TABLE sample_www_access ( time integer, host varchar, path varchar, referer varchar, code integer, agent varchar, size integer, method varchar ) SERVER treasuredata_server OPTIONS ( apikey 'your_api_key', database 'sample_datasets', query_engine 'presto', table 'www_access' );

SELECT code, count(1) FROM sample_www_access WHERE time BETWEEN 1412121600 AND 1414800000 GROUP BY code;

code | count ------+------- 404 | 17 200 | 4981 500 | 2 (3 rows)

CREATE FOREIGN TABLE nginx_status_summary ( text varchar, cnt integer ) SERVER treasuredata_server OPTIONS ( apikey 'your_api_key', database 'api_staging', query_engine 'hive', query 'SELECT c.text, COUNT(1) AS cnt FROM nginx_access n JOIN mitsudb.codes c ON CAST(n.status AS bigint) = c.code WHERE TD_TIME_RANGE(n.time, ''2015-07-05'') GROUP BY c.text' );

SELECT * FROM nginx_status_summary; text | cnt ---------------+---------- OK | 10123456 Forbidden | 12 Unauthorized | 3211 :

CREATE FOREIGN TABLE my_www_access ( time integer, host varchar, path varchar, referer varchar, code integer, agent varchar, size integer, method varchar ) SERVER treasuredata_server OPTIONS ( apikey 'your_api_key', database 'mydb', query_engine 'presto', table 'www_access', import_file_size '67108864', atomic_import 'true' );

INSERT INTO my_www_access SELECT * FROM sample_www_access; INSERT 0 5000 ```

Also, you can specify other API endpoint.

SERVER treasuredata_fdw OPTIONS ( endpoint 'https://ybi.jp-east.idcfcloud.com' apikey 'your_api_key', :

You can also use IMPORT FOREIGN SCHEMA. It will import the tables on the specified Treasure Data database into the Postgres schema. CREATE SCHEMA local_schema; IMPORT FOREIGN SCHEMA sample_datasets FROM SERVER treasuredata_server INTO local_schema OPTIONS ( apikey 'your_api_key', query_engine 'presto' ); \det+ local_schema. List of foreign tables Schema | Table | Server | FDW Options | Description --------------|------------|---------------------|--------------------------------------------------------------------------------------------------------------------------------|------------- local_schema | nasdaq | treasuredata_server | (apikey 'your_api_key', database 'sample_datasets', query_engine 'presto', "table" 'nasdaq') | local_schema | www_access | treasuredata_server | (apikey 'your_api_key', database 'sample_datasets', query_engine 'presto', "table" 'www_access') | (2 rows) Note that "time" column will NOT be imported by IMPORT FOREIGN SCHEMA.

Table Options

• apikey : API Key for Treasure Data. See Get API Keys.
• database : Database name on Treasure Data that the foreign table corresponds to.
• table : Table name on Treasure Data that the foreign table corresponds to. This option can't be used with query option.
• query: SELECT statement that is sent to Treasure Data directly. The SQL needs to be a valid Presto/Hive query on Treasure Data and return the same column names as columns of the foreign table. Also, this FDW with this option doesn't support INSERT statement. This option can't be used with table option.
• query_engine : Query engine name (presto or hive) that queries on the foreign table use.
• query_download_dir : If it's set, a query result is downloaded to the specified directory first and then each row is fetched from the downloaded file. If it's not set, query result rows are directly fetched from stream. This option can be useful when a result file is large and a TCP connection might be disconnected during streaming fetch. The default value is not set (= streaming fetch).
• endpoint: Treasure Data's API endpoint (optional).
• import_file_size : Approximate maximum size of chunk files uploaded to Treasure Data. The default value is 134217728 (128MB).
• atomic_import : Flag (true or false) of whether uploaded chunk files get visible atomically. The default value is false

On IMPORT FOREIGN SCHEMA, you must specify apikey and query_engine. You can also specify endpoint which is optional. Those values will be set into the imported tables' option. You can use ALTER FOREIGN TABLE to modify table options if you want to modify after import.

INSERT INTO statement

This FDW supports INSERT INTO statement. With atomic_import is false, the FDW imports INSERTed rows as follows.

1. At the beginning of INSERT INTO query, an empty chunk file is created.
2. Each INSERTed row is appended to the chunk file.
3. If the written size exceeds a threshold specified by import_file_size, the chunk file is uploaded to Treasure Data and imported into the target table. And then a new empty chunk file is created again.
4. When all INSERTed rows are appended, the last chunk file is uploaded to Treasure Data and imported into the target table.

With atomic_import is true, the FDW imports INSERTed rows as follows.

1. At the beginning of INSERT INTO query, an empty chunk file is created. And a temporary table is created on Treasure Data.
2. Each INSERTed row is appended to the chunk file.
3. If the written size exceeds a threshold specified by import_file_size, the chunk file is uploaded to Treasure Data and imported into the temporary table. And then a new empty chunk file is created again.
4. When all INSERTed rows are appended, the last chunk file is uploaded to Treasure Data and imported into the temporary table.
5. Finally, the imported rows in the temporary table are atomically copied to the target table using INSERT INTO (target table) SELECT * FROM (temporary table) query on Treasure Data.

Pros and Cons of atomic_import are:

• Pros : Even if some chunk files are uploaded and imported to Treasure Data, they are rolled back when the INSERT INTO query is aborted after that.
• Cons : It needs to issue an INSERT INTO (target table) SELECT * FROM (temporary table) query on Treasure Data. It takes an extra time and resource to finish the INSERT INTO statement.

Prepare Linux development environment

$ docker/build.sh $ docker/run.sh And then, follow the instructions from run.sh.

Regression test

$ TD_TEST_APIKEY=<your_api_key> ./setup_regress <hive|presto> $ make installcheck