Creating an external table from a Yandex Object Storage bucket table using a configuration file

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Updated at August 29, 2024

Getting started
Set up your web server with a configuration file
Create an external table
Delete the resources you created

To create an external table from a table in a Yandex Object Storage bucket, you need to provide a static access key for the service account in the query. You can do this using the S3 protocol and a configuration file stored on the HTTP server.

To create an external table using a configuration file:

If you no longer need the resources you created, delete them.

Getting started

Prepare the infrastructure:

Manually

Terraform

Create a Managed Service for Greenplum® cluster with any suitable configuration.
In the cluster subnet, set up a NAT gateway and create a security group allowing all incoming and outgoing traffic from all addresses.
Create a virtual machine on Linux in the same cloud network as the Managed Service for Greenplum® cluster.
Create a Object Storage bucket with restricted access. Upload the example.csv file with a test table to it:
```
10.2010
```
Create a static access key for the service account.

If you do not have Terraform yet, install it.
Get the authentication credentials. You can add them to environment variables or specify them later in the provider configuration file.
Configure and initialize a provider. There is no need to create a provider configuration file manually, you can download it.
Place the configuration file in a separate working directory and specify the parameter values. If you did not add the authentication credentials to environment variables, specify them in the configuration file.
In the working directory, create a file called example.csv with a test table:
```
10.2010
```
Download the infrastructure configuration file to the same working directory.

This file describes:
- Network.
- Subnet
- Service account with the static access key.
- Managed Service for Greenplum® cluster.
- Bucket to place the example.csv file into.
- Virtual machine with Ubuntu 20.04.
In the greenplum-s3-vm.tf file, specify:
- Password for user to utilize for Managed Service for Greenplum® cluster access.
- Virtual machine image ID.
- Username and path to the SSH key for virtual machine access.
- Folder ID for the same service account as specified in the provider settings.
- Bucket name that must be unique throughout Object Storage.
In the terminal window, go to the directory containing the infrastructure plan.
To verify that the config files are correct, run the command below:
```
terraform validate
```
If there are any errors in the configuration files, Terraform will point them out.
Create the infrastructure required to follow the steps provided in this tutorial:
1. Run the command to view planned changes:
```
terraform plan
```
  If the resource configuration descriptions are correct, the terminal will display a list of the resources to modify and their parameters. This is a test step. No resources are updated.
2. If you are happy with the planned changes, apply them:
  1. Run the command:
```
terraform apply
```
  2. Confirm the update of resources.
  3. Wait for the operation to complete.
All the required resources will be created in the specified folder. You can check resource availability and their settings in the management console.
To retrieve the static key parameters, run the command below in the working directory:
```
terraform output -raw access_key > static-key.txt && \
echo \n >> static-key.txt && \
terraform output -raw secret_key >> static-key.txt
```
The command saves the static key ID and the static key you will need later to a file called static-key.txt.
Go to the management console and set up an NAT gateway for the subnet hosting your cluster.

Set up your web server with a configuration file

Set up a web server on your virtual machine and create an s3 configuration file on your web server:

Connect to the virtual machine over SSH.

Create a folder called /opt/gp_http_server and place your s3.config file with the static key parameters and the other configuration settings for the s3 protocol in this folder:

sudo mkdir /opt/gp_http_server

Contents of the s3.config file:

[default]
accessid = "<static_key_ID>"
secret = "<static_key>"
threadnum = 4
chunksize = 67108864
low_speed_limit = 10240
low_speed_time = 60
encryption = true
version = 2
proxy = ""
autocompress = true
verifycert = true
server_side_encryption = ""
# gpcheckcloud config
gpcheckcloud_newline = "\n"

In the /etc/systemd/system/ folder, put a web server config file named gp_s3_config_http.service:

[Unit]
Description=HTTP server config to connect Greenplum with Object Storage
After=network.target

[Service]
KillMode=process
Restart=on-failure
Type=simple
User=root
ExecStart=python3 -m http.server 8553 --directory /opt/gp_http_server

[Install]
WantedBy=multi-user.target

Start your web server:

sudo systemctl daemon-reload && \
sudo systemctl enable gp_s3_config_http && \
sudo systemctl start gp_s3_config_http

To check the state of the web server, run the command below:
```
sudo systemctl status gp_s3_config_http
```

Create an external table

Connect to the Managed Service for Greenplum® cluster.

Run a query to create an external table referencing the example.csv table in your bucket:

CREATE READABLE EXTERNAL TABLE s3_ext_table(id int, year int)
LOCATION('s3://storage.yandexcloud.net/<bucket_name>/example.csv config_server=http://<VM_private_IP>:8553/s3.config region=ru-central1-a')
FORMAT 'csv';

A successful query will return the following response:

CREATE EXTERNAL TABLE

Query the external table for data:

SELECT * FROM s3_ext_table;

Expected result:

 id | year
----+------
 10 | 2010
(1 row)

Delete the resources you created

Some resources are not free of charge. To avoid paying for them, delete the resources you no longer need:

Manually

Terraform

Delete the VM.
If you reserved a public static IP address for the VM, delete it.
Delete the bucket in Object Storage.
Delete the Managed Service for Greenplum® cluster.
Delete the service account.
Delete the subnet.
Delete the route table.
Delete the NAT gateway.
Delete the cloud network.

To delete the infrastructure created with Terraform:

In the terminal window, go to the directory containing the infrastructure plan.
Delete greenplum-s3-vm.tf.
Run this command:
```
terraform validate
```
If there are any errors in the configuration files, Terraform will point them out.
Confirm updating the resources.
1. Run the command to view planned changes:
```
terraform plan
```
  If the resource configuration descriptions are correct, the terminal will display a list of the resources to modify and their parameters. This is a test step. No resources are updated.
2. If you are happy with the planned changes, apply them:
  1. Run the command:
```
terraform apply
```
  2. Confirm the update of resources.
  3. Wait for the operation to complete.
This will delete all the resources described in greenplum-s3-vm.tf.

Greenplum® and Greenplum Database® are registered trademarks or trademarks of VMware, Inc. in the United States and/or other countries.

Creating an external table from a Yandex Object Storage bucket table using a configuration file

Getting startedGetting started

Set up your web server with a configuration fileSet up your web server with a configuration file

Create an external tableCreate an external table

Delete the resources you createdDelete the resources you created

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Getting started

Set up your web server with a configuration file

Create an external table

Delete the resources you created