Migrating a database from Greenplum® to PostgreSQL
You can migrate a database from Greenplum® to the PostgreSQL cluster using Yandex Data Transfer.
To transfer a database from Greenplum® to PostgreSQL:
If you no longer need the resources you created, delete them.
Getting started
For clarity, we will create all required resources in Yandex Cloud. Prepare the infrastructure:
-
Create a Yandex Managed Service for Greenplum® source cluster in any suitable configuration with the
gp-user
admin username and public hosts. -
Create a Yandex Managed Service for PostgreSQL target cluster in any suitable configuration with publicly available hosts. When creating a cluster, specify:
- Username:
pg-user
- DB name:
db1
- Username:
-
If you are using security groups in clusters, make sure they are set up correctly and allow connecting to the clusters:
-
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.
-
Download the greenplum-postgresql.tf
configuration file to the same working directory.This file describes:
- Networks and subnets for hosting the clusters.
- Security groups to connect to clusters.
- Managed Service for Greenplum® source cluster.
- Managed Service for PostgreSQL target cluster.
- Target endpoint.
- Transfer.
-
In the
greenplum-postgresql.tf
file, specify the administrator passwords and versions of Greenplum® and PostgreSQL. -
Run the
terraform init
command in the directory with the configuration file. This command initializes the provider specified in the configuration files and enables you to use the provider resources and data sources. -
Make sure the Terraform configuration files are correct using this command:
terraform validate
If there are any errors in the configuration files, Terraform will point them out.
-
Create the required infrastructure:
-
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.
-
If you are happy with the planned changes, apply them:
-
Run the command:
terraform apply
-
Confirm the update of resources.
-
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
. -
Set up the transfer
-
Create a source endpoint of the
Greenplum®
type and specify the cluster connection parameters in it:- Connection type:
Managed Service for Greenplum cluster
- Managed Service for Greenplum cluster:
<name_of_Greenplum®_source_cluster>
from the drop-down list - Database:
postgres
- User:
gp-user
- Password:
<user_password>
- Service object schema:
public
- Connection type:
-
Create a target endpoint and a transfer:
ManuallyTerraform-
Create a target endpoint of the
PostgreSQL
type and specify the cluster connection parameters in it:- Installation type:
Yandex Managed Service for PostgreSQL cluster
- Managed Service for PostgreSQL cluster:
<name_of_PostgreSQL_target_cluster>
from the drop-down list - Database:
db1
- User:
pg-user
- Password:
<user_password>
- Installation type:
-
Create a transfer of the Snapshot type that will use the created endpoints.
Replication is not available for this endpoint pair, but you can set up regular copying when creating a transfer. To do this, in the Snapshot field under Transfer parameters, select Regular and specify the copy interval. This will activate a transfer automatically after the specified time interval.
Warning
Before configuring regular copying, make sure that the target endpoint parameters include either a
DROP
or aTRUNCATE
cleanup policy. Otherwise, data on the target will be duplicated.
-
Specify the variables in the
greenplum-postgresql.tf
file:gp_source_endpoint_id
: ID of the source endpoint.transfer_enabled
: Set to1
to enable transfer creation.
-
Make sure the Terraform configuration files are correct using this command:
terraform validate
If there are any errors in the configuration files, Terraform will point them out.
-
Create the required infrastructure:
-
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.
-
If you are happy with the planned changes, apply them:
-
Run the command:
terraform apply
-
Confirm the update of resources.
-
Wait for the operation to complete.
-
-
-
Activate the transfer
-
Connect to the Managed Service for Greenplum® cluster, create a table named
x_tab
, and populate it with data:CREATE TABLE x_tab ( id NUMERIC, name CHARACTER(5) ); CREATE INDEX ON x_tab (id); INSERT INTO x_tab (id, name) VALUES (40, 'User1'), (41, 'User2'), (42, 'User3'), (43, 'User4'), (44, 'User5');
-
Activate the transfer and wait for its status to change to Completed.
-
To verify that the data has transferred correctly, connect to the Managed Service for PostgreSQL target cluster and make sure that the columns of the
x_tab
table in thedb1
database match those of the source databasex_tab
table:SELECT id, name FROM db1.public.x_tab;
┌─id─┬─name──┐ │ 40 │ User1 │ │ 41 │ User2 │ │ 42 │ User3 │ │ 43 │ User4 │ │ 44 │ User5 │ └────┴───────┘
Check the copy function upon re-activation
-
In the target endpoint parameters select either a
DROP
or aTRUNCATE
cleanup policy. -
In the
x_tab
table, delete the row with the41
ID and update the one with the42
ID:DELETE FROM x_tab WHERE id = 41; UPDATE x_tab SET name = 'Key3' WHERE id = 42;
-
Reactivate the transfer and wait for its status to change to Completed.
-
Check the changes in the
x_tab
table on the PostgreSQL target:SELECT id, name FROM db1.public.x_tab;
┌─id─┬─name──┐ │ 42 │ Key3 │ │ 40 │ User1 │ │ 43 │ User4 │ │ 44 │ User5 │ └────┴───────┘
Delete the resources you created
Some resources are not free of charge. To avoid paying for them, delete the resources you no longer need:
-
Make sure the transfer has the Completed status and delete it.
-
Delete the clusters:
ManuallyTerraformIf you created your resources using Terraform:
-
In the terminal window, go to the directory containing the infrastructure plan.
-
Delete the
greenplum-postgresql.tf
configuration file. -
Make sure the Terraform configuration files are correct using this command:
terraform validate
If there are any errors in the configuration files, Terraform will point them out.
-
Confirm updating the resources.
-
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.
-
If you are happy with the planned changes, apply them:
-
Run the command:
terraform apply
-
Confirm the update of resources.
-
Wait for the operation to complete.
-
All the resources described in the
greenplum-postgresql.tf
configuration file will be deleted. -
-