Snowflake

The Snowflake destination writes data to Snowflake. You can use the Snowflake destination to write to any accessible Snowflake database, including those hosted on Amazon S3, Microsoft Azure, and private Snowflake installations.

The Snowflake destination stages data to an internal table before writing it to Snowflake.

When you configure the destination, you specify the Snowflake region, database, table, and schema to use. You also specify the user account and password. You can optionally specify a custom role that overrides the default role for the user account. The user account or the custom role must have the required Snowflake privileges.

You can also use a connection to configure the destination.

You specify the write mode to use: overwrite, append, or merge. When appending data, the destination creates the table if it does not exist. To merge data, you configure additional merge properties.

You specify how to map record fields to table columns and select the behavior for data type mismatches. You can configure the origin to preserve existing capitalization for column names. You can also specify the number of connections to use and configure additional Snowflake properties.

Note: When the pipeline runs on a Databricks cluster, use Databricks runtime 6.1 or above for optimal compatibility.

Required Privileges and Custom Roles

The Snowflake destination requires a Snowflake role that grants the following privileges:

Object Privilege
Schema CREATE TABLE
Table SELECT, INSERT
If you create a custom role with the required privileges, define the role that the stage uses in one of the following ways:
Assign the custom role as the default role
In Snowflake, assign the custom role as the default role for the Snowflake user account specified in the stage. A Snowflake user account is associated with a single default role.
Override the default role with the custom role
In the stage, select Use Snowflake Role on the connection information tab. Then, specify the name of the custom role. The custom role overrides the default role assigned to the Snowflake user account specified in the stage.
For example, you might define custom roles in Snowflake for specific data sources, and then specify one of the roles when using a Snowflake destination to load data.

Write Mode

The write mode determines how the Snowflake destination writes to Snowflake.
Overwrite existing table
If the table exists, the destination drops and recreates the table. Then, the destination inserts all data to the table.
Append rows to existing table or create table if none exists
If the table exists, the destination appends data to the table. If the table does not exist, the destination creates the table.
Append data to an existing table only when each record has a unique primary key. If a row with the same primary key exists in the table, the pipeline fails with a primary key violation.
Merge rows to existing table
The destination merges data with data in an existing table. The destination performs inserts, updates, and deletes based on the specified merge properties.

Merge Properties

When using the Merge write mode, you configure the following properties:
Join Key
One or more key columns in the table. Used to perform updates and deletes and to ensure that duplicate rows do not exist for inserts. Pipeline records must include a matching field name.
When Clause
Action that the destination performs when a record meets the specified conditions. You can specify multiple merge configurations for the destination to perform.
Important: The destination performs the writes in the specified order. Best practice is to list merge configurations with the smallest number of affected records first, progressing to the largest number of affected records. When defining multiple merge configurations of the same type, carefully consider the order that you use.
When defining a merge configuration, you define the following properties:
  • When Clause - Determines when an action is performed. Select one of the following options:
    • When Matched - Use with the Update and Delete operations. Updates or deletes a row upon finding a matching join key.
    • When Not Matched - Use with the Insert operation. Inserts a row when no matching join key exists in the table.
    • When Not Matched by Source - Do not use. Snowflake does not support this option.

    For example, say the Join Key is set to id, the When Clause property is set to When Matched, and Operation property is set to Update. When an ID in the record matches an ID in the table, the record is written to the table, updating the existing row.

  • Additional Condition - An optional additional condition for the merge. Use $input. to prefix field names in records, and $target. to prefix column names in the table.

    For example, if the Join Key is id and you set an additional condition of $input.delete=true, then the merge only occurs when the ID in the record matches an ID in the table and the delete field in the record is set to true.

  • Operation - The operation to perform: Insert, Update, or Delete. The operation that you can use is dependent on the When Clause option that you select.

    For example, the Insert operation can only be used when the When Clause is set to When Not Matched.

Snowflake Data Types

When writing to Snowflake, the Snowflake destination converts the Spark data types used in the pipeline to Snowflake data types. The following table describes how this conversion occurs.

Snowflake data types that are not listed in the table are not supported.
Spark Data Type Snowflake Data Type
ArrayType VARIANT
BooleanType BOOLEAN
ByteType INTEGER
DateType DATE
DecimalType DECIMAL
DoubleType DOUBLE
FloatType FLOAT
IntegerType INTEGER
LongType INTEGER
MapType VARIANT
ShortType INTEGER
StringType VARCHAR(N) for specified lengths, otherwise VARCHAR
StructType VARIANT
TimestampType TIMESTAMP

Configuring a Snowflake Destination

Configure the Snowflake destination to write data to Snowflake.

  1. On the Properties panel, on the General tab, configure the following properties:
    General Property Description
    Name Stage name.
    Description Optional description.
    Stage Library Stage library to use to connect to Snowflake:
    • Snowflake cluster-provided libraries - The cluster where the pipeline runs has Snowflake libraries installed, and therefore has all of the necessary libraries to run the pipeline.
    • Snowflake Transformer-provided libraries - Transformer passes the necessary libraries with the pipeline to enable running the pipeline.

      Use when running the pipeline locally or when the cluster where the pipeline runs does not include the Snowflake libraries.

    Note: When using additional Snowflake stages in the pipeline, ensure that they use the same stage library.
  2. On the Connection tab, configure the following properties:
    Connection Property Description
    Connection Connection that defines the information required to connect to an external system.

    To connect to an external system, you can select a connection that contains the details, or you can directly enter the details in the pipeline. When you select a connection, Control Hub hides other properties so that you cannot directly enter connection details in the pipeline.

    To create a new connection, click the Add New Connection icon: . To view and edit the details of the selected connection, click the Edit Connection icon: .

    Snowflake Region Region where the Snowflake warehouse is located. Select one of the following regions:
    • An available Snowflake region.
    • Other - Use to specify a Snowflake region not listed in the property.
    • Custom JDBC URL - Use to specify a virtual private Snowflake installation.
    Custom Snowflake Region Custom Snowflake region. Available when using Other as the Snowflake region.
    Virtual Private Snowflake URL Custom JDBC URL to use when using a virtual private Snowflake installation.
    Account Snowflake account name.
    User Snowflake user name.

    The user account or the custom role that overrides the default role for this user account must have the required Snowflake privileges.

    For details, see Required Privileges and Custom Roles.

    Password Snowflake password.
    Use Snowflake Role Overrides the default role for the specified user account.

    The custom role must have the required Snowflake privileges.

    Snowflake Role Name Name of the custom Snowflake role to use.
    Connection Properties Additional Snowflake Connection for Spark properties to use. For information about additional options, see the Snowflake documentation.

    To add properties, click the Add icon and define the property name and value. Specify the property names and values as expected by Snowflake.

    You can use simple or bulk edit mode to configure the properties.

    Tip: To secure sensitive information, you can use credential stores or runtime resources.
    Warehouse Snowflake warehouse.
    Database Snowflake database.
    Schema Snowflake schema.
  3. On the Table tab, configure the following properties:
    Table Property Description
    Table Name of the Snowflake table to write to.
    Keep Column Case Preserves the case used in field names when writing data to Snowflake.

    When not selected, field names are converted to all caps when writing to Snowflake, unless the names are enclosed in quotation marks.

    Column Mapping Mode Mode to map record fields to Snowflake table columns:
    • By Order - Record fields map to table columns based on order.
    • By Name - Record fields map to table columns based on names. The mapping is not case-sensitive.
    Mismatch Behavior Action to take when field data is the wrong data type for the mapped table column:
    • Error - Generates an error that stops the pipeline.
    • Ignore - Drops the invalid data from the record and inserts a null value in the table column.
    Write Mode Write mode for the stage:
    • Overwrite existing table - If the table exists, the destination drops and recreates the table. Then, the destination inserts all data to the table.
    • Append rows to existing table or create table if none exists - If the table exists, the destination appends data to the table. If the table does not exist, the destination creates the table.

      Append data to an existing table only when each record has a unique primary key. If a row with the same primary key exists in the table, the pipeline fails with a primary key violation.

    • Merge rows to existing table - The destination merges data with data in an existing table. The destination performs inserts, updates, and deletes based on the specified merge properties.
    Join Key One or more key columns in the table. Used to perform updates and deletes and to ensure that duplicate rows do not exist for inserts. Pipeline records must include a matching field name.
    Merge Configuration Action that the destination performs when a record meets the specified conditions. You can specify multiple merge configurations for the destination to perform.
    Important: The destination performs the writes in the specified order. Best practice is to list merge configurations with the smallest number of affected records first, progressing to the largest number of affected records. When defining multiple merge configurations of the same type, carefully consider the order that you use.
    Configure the following properties:
    • When Clause - Determines when an action is performed. Select one of the following options:
      • When Matched - Use with the Update and Delete operations. Updates or deletes a row upon finding a matching join key.
      • When Not Matched - Use with the Insert operation. Inserts a row when no matching join key exists in the table.
      • When Not Matched by Source - Do not use. Snowflake does not support this option.
    • Additional Condition - An optional additional condition for the merge. Use $input. to prefix field names in records, and $target. to prefix column names in the table.
    • Operation - The operation to perform: Insert, Update, or Delete. The operation that you can use is dependent on the When Clause option that you select.

    Click the Add icon to specify another merge clause.

    Available with the Merge Rows to Existing Table write mode.

  4. Optionally, on the Advanced tab, configure the following property:
    Advanced Property Description
    Connection Pool Maximum number of connections to Snowflake that the stage uses.

    Default is 4.

    Increasing this property can improve performance. However, Snowflake warns that setting this property to an arbitrarily high value can adversely affect performance. The default is the recommended value.