Destination Snowflake setup guide #

The following steps refer the extracted Arcion self-hosted CLI download as the $REPLICANT_HOME directory.

Required permissions #

• Make sure the user possesses the following privileges on the catalogs or schemas where you want Replicant to replicate tables to:

  • CREATE TABLE
  • CREATE STAGE

• To create catalogs or schemas on the target Snowflake system, you must grant CREATE DATABASE or CREATE SCHEMA privileges respectively to the user.

• If the user does not possess CREATE DATABASE privilege, then follow these steps:

  1. Create a database manually with the name blitzz.
  2. Grant all privileges for the blitzz database to that user.

  Replicant uses this io database to maintain internal checkpoint and metadata.

I. Set up connection configuration #

Specify our Snowflake connection details to Replicant with a connection configuration file. You can find a sample connection configuration file snowflake.yaml in the $REPLICANT_HOME/conf/conn directory.

In the connection configuration file, you need to configure the following:

• Target Snowflake server connection
• Stage for bulk loading

Configure target Snowflake server connection #

Note: All communications with Snowflake happens through port 443, the standard port for HTTPS. So all data is encrypted and secure with SSL by default.

• RSA key pair authentication
• Basic username and password authentication

Connect using username and password #

To connect to Snowflake with basic username and password authentication, you have two options:

type: SNOWFLAKE

host: SNOWFLAKE_HOSTNAME
port: PORT_NUMBER 
warehouse: "WAREHOUSE_NAME"

username: "USERNAME"
password: "PASSWORD"

max-connections: 20 #Specify the maximum number of connections replicant can open in Snowflake
max-retries: 10
retry-wait-duration-ms: 1000

Configure stage #

Stage configuration allows you to tune native or external staging area for bulk loading. For more information, see Stage configuration.

Use RSA key pair for authentication #

You can also choose to use Snowflake’s key pair authentication support for enhanced authentication security instead of using basic authentication via username and password.

To set up key pair authentication using RSA keys, follow these steps:

Generate the private key #

From your command line, execute the following command to generate an encrypted private key:

openssl genrsa 2048 | openssl pkcs8 -topk8 -inform PEM -v1 PBE-SHA1-RC4-128 -out rsa_key.p8

The command generates a private key in PEM format:

-----BEGIN ENCRYPTED PRIVATE KEY-----
MIIFHDBOBgkqhkiG9w0BBQ0wQTApBgkqhkiG9w0BBQwwHAQIK0h8dqI1n5sCAggA
MAwGCCqGSIb3DQIJBQAwFAYIKoZIhvcNAwcECNDwqMf6Xx1pBIIEyNmf044S+pEQ
...
-----END ENCRYPTED PRIVATE KEY-----

Important: The preceding command to generate an encrypted key prompts for a passphrase to grant access to the key. We recommend using a passphrase that complies with PCI DSS standards to protect the generated private key. We also recommend storing the passphrase in a secure location. When using an encrypted key to connect to Snowflake, you need to input the passphrase during the initial connection. The passphrase only protects the private key and never reaches Snowflake servers.

To generate a long and complex passphrase based on PCI DSS standards, follow these steps:

• Go to the PCI Security Standards Document Library.
• For PCI DSS, select the most recent version and your desired language.
• Complete the form to access the document.
• Search for Passwords/passphrases must meet the following: and follow the recommendations for password/passphrase requirements, testing, and guidance.

Generate a public key #

From the command line, generate the public key by referencing the private key. The following command references the private key from a file rsa_key.p8 that you create in the previous step:

openssl rsa -in rsa_key.p8 -pubout -out rsa_key.pub

The command generates a public key in PEM format:

-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAslwTa+Lj5SMI58GiDzWq
0rwj4FBymfKzHT16RXecnMcx7uI6KsVpqfh9HH0FMb/3C6YEMeGPkaRmKvXYjM5s
...
-----END PUBLIC KEY-----

Store the private and public keys securely #

After following the preceding steps, the private and public key files are saved in a local directory of your system. Note down the path to those files. The private key is stored using the PKCS#8 (Public Key Cryptography Standards) format and is encrypted using the passphrase you specified in the first step.

However, maintain caution in protecting the file from unauthorized access using the file permission mechanism your operating system provides. You must take responsibility to secure the file when not in use.

Assign the public key to a Snowflake user #

Execute the following command to assign the public key to a Snowflake user.

alter user jsmith set rsa_public_key='MIIBIjANBgkqh...';

• Only security administrators, for example, users with the SECURITYADMIN role or higher, can alter a user.
• Exclude the public key delimiters in the SQL statement.

Verify the user’s public key fingerprint #

Execute the following command to verify the user’s public key:

DESC USER jsmith;

The command output resembles the following:

+---------------------+-----------------------------------------------------+---------+----------------------------------------------+
| property            | value                                               | default | description                                  |
+---------------------+-----------------------------------------------------+---------+----------------------------------------------+
| NAME                | JSMITH                                              | null    | Name                                         |
...
...
| RSA_PUBLIC_KEY      | MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAslwT... | null    | RSA public key of the user                   |
| RSA_PUBLIC_KEY_FP   | SHA256:nvnONUsfiuycCLMXIEWG4eTp4FjhVUZQUQbNpbSHXiA= | null    | Fingerprint of user's RSA public key.        |
| RSA_PUBLIC_KEY_2    | null                                                | null    | Second RSA public key of the user            |
| RSA_PUBLIC_KEY_2_FP | null                                                | null    | Fingerprint of user's second RSA public key. |
...
+---------------------+-----------------------------------------------------+---------+----------------------------------------------+

Edit the connection configuration file #

You need to modify Replicant’s connection configuration file for Snowflake and include RSA key information there. Specifically, add the following parameters to the connection configuration file:

private-key-path: "/PATH_TO_GENERATED_KEY/rsa_key.p8"
private-key-passphrase: "PRIVATE_KEY_PASSPHRASE"

Replace the following:

• PATH_TO_GENERATED_KEY: the local directory path to the rsa_key.p8 keyfile
• PRIVATE_KEY_PASSPHRASE: the private key passphrase you in the first step

Note: If you specify the private-key-path and private-key-passphrase parameters, you don’t need to specify the password parameter in the connection configuration file.

II. Set up Applier configuration #

To configure replication mode according to your requirements, specify your configuration in the Applier configuration file. You can find a sample Applier configuration file snowflake.yaml in the $REPLICANT_HOME/conf/dst directory.

You can configure Snowflake for operating in either snapshot or realtime modes.

Configure snapshot mode #

For operating in snapshot mode, specify your configuration under the snapshot section of the conifiguration file. For example:

snapshot:
  threads: 16 #Specify the maximum number of threads Replicant should use for writing to the target

  batch-size-rows: 100_000
  txn-size-rows: 1_000_000

  #If bulk-load is used, Replicant will use the native bulk-loading capabilities of the target database
  bulk-load:
    enable: true|false #Set to true if you want to enable bulk loading
    type: FILE|PIPE #Specify the type of bulk loading between FILE and PIPE
    serialize: true|false #Set to true if you want the generated files to be applied in serial/parallel fashion

    #For versions 20.09.14.3 and beyond
    native-load-configs: #Specify the user-provided LOAD configuration string which will be appended to the s3 specific LOAD SQL command

For more information about the Applier parameters for snapshot mode, see Snapshot mode.

Enable clustering #

To improve performance, primary keys and unique keys need to be clustering keys on Snowflake side. Replicant achieves that by making primary and unique keys as clustering keys when Replicant creates the tables.

To enable clustered table creation, set the force-use-clustered-key parameter to true in your Applier configuration file. for-use-clustered-key defaults to false and Snowflake tables don’t have clustering keys designated to them.

Important: You must run Replicant with the --replace option for clustering to work.

For more information on Snowflake clustering, see Clustering Keys & Clustered Tables.

Configure realtime mode #

For operating in realtime mode, specify your configuration under the realtime section of the conifiguration file. For example:

realtime:
  threads: 8 #Specify the maximum number of threads Replicant should use for writing to the target
  max-retries-per-op: 30 #Specify the maximum amount of retries for a failed operation
  retry-wait-duration-ms: 5000 #Specify the time in milliseconds Replicant should wait before re-trying a failed operation
  cdc-stage-type: FILE #Enter your cdc-stage-type

When operating in realtime mode, pay attention to the following details:

• Make sure that the number of threads equals the number of tables.
• Enable primary key or unique key logging if source table has primary key or unique key. If table does not possess any primary key, then only enable full logging. For example, if you load data from Oracle, Oracle supports unique key logging.
• You might want to select any table in your Snowflake dashboard while operating. Due to a Snowflake limitation, problems may arise if table name contains lowercase. Therefore, execute the following command first:

  ALTER SESSION SET QUOTED_IDENTIFIERS_IGNORE_CASE = FALSE;
  

  After executing the preceding command, you can select table with lowercase names by surrounding the names with double quotation marks.

For more information about the configuration parameters for realtime mode, see Realtime mode.

Enable Type-2 CDC #

From version 22.07.19.3 onwards, Arcion supports Type-2 CDC for Snowflake as the target. For more information, see Type-2 CDC and cdc-metadata-type.