Snowflake - Select

Overview

You can use this Snap to fetch data from a database by providing a table name and configuring the Snowflake connection. The Snap produces the records from the database on its output view which can then be processed by a downstream Snap.

Note: JSON paths can be used in a query, and values from an incoming document will be substituted into the query. However, documents missing values for a given JSON path will be written to Snap's error view. After a query is executed, the query's results are merged into the incoming document, overwriting any existing keys' values. If there are no results from the query, the original document is output.

Read-type Snap
Works in Ultra Tasks. However, we recommend that you not use this Snap in an Ultra Pipeline

Prerequisites

You must have minimum permissions on the database to execute Snowflake Snaps. To understand if you already have them, you must retrieve the current set of permissions. The following commands enable you to retrieve those permissions:

SHOW GRANTS ON DATABASE <database_name>
        SHOW GRANTS ON SCHEMA <schema_name>
        SHOW GRANTS TO USER <user_name>

Security Prererequisites

You must have the following permissions in your Snowflake account to execute this Snap:

Usage (DB and Schema): Privilege to use the database, role, and schema.

The following commands enable minimum privileges in the Snowflake Console:

grant usage on database <database_name> to role <role_name>;
              grant usage on schema <database_name>.<schema_name>;

Learn more about Snowflake privileges: Access Control Privileges.

Internal SQL Commands

This Snap uses the SELECT command internally. It enables you to query the database and retrieve a set of rows.

Known Issues

Because of performance issues, all Snowflake Snaps now ignore the Cancel queued queries when pipeline is stopped or if it fails option for Manage Queued Queries, even when selected. Snaps behave as though the default Continue to execute queued queries when the Pipeline is stopped or if it fails option were selected.

Behaviour Change

From 4.30 Release, the Snowflake - Select Snap writes the output value as-is for FLOAT or DOUBLE datatype columns if these columns have the value as NaN (Not a Number). Earlier, the Snap displayed an exception error when the FLOAT or DOUBLE datatype column has the value as NaN. This behavior is not backward compatible.

Snap views


View	Description	Examples of upstream and downstream Snaps
Input	A document that provides values for one or more properties of the Snap or for pass-through purpose. A dynamic where clause can be defined by providing values upstream. As the Mapper Snap can provide constants, pipeline parameters mapped into variables then can be used in the where clause or even in the table/schema properties.	Mapper Binary to Document
Output	This Snap has one document output view by default. A second view can be added to show the metadata for the table as a Document. The metadata document can then be fed into the second input view of Snowflake - Insert or Bulk Load Snaps so that the table is created in Snowflake with a similar schema as the source table. The Snap will output one document for every record retrieved, hence any document processing Snap can be used downstream. Document for each record retrieved. Special types such as TIMESTAMP, TIME are converted into SnapLogic internal date type representations which then can be consumed by downstream Snaps just like any other data type. Queries produced by the Snap have an equivalent format: SELECT * FROM [table] WHERE [where clause] ORDER BY [ordering] LIMIT [limit] OFFSET [offset]	Mapper Snowflake - Execute
Error	Error handling is a generic way to handle errors without losing data or failing the Snap execution. You can handle the errors that the Snap might encounter when running the pipeline by choosing one of the following options from the When errors occur list under the Views tab. The available options are: Stop Pipeline Execution Stops the current pipeline execution when an error occurs. Discard Error Data and Continue Ignores the error, discards that record, and continues with the remaining records. Route Error Data to Error View Routes the error data to an error view without stopping the Snap execution. Learn more about Error handling in Pipelines.

Snap settings

Legend:

Expression icon (): Allows using JavaScript syntax to access SnapLogic Expressions to set field values dynamically (if enabled). If disabled, you can provide a static value. Learn more.
SnapGPT (): Generates SnapLogic Expressions based on natural language using SnapGPT. Learn more.
Suggestion icon (): Populates a list of values dynamically based on your Snap configuration. You can select only one attribute at a time using the icon. Type into the field if it supports a comma-separated list of values.
Upload : Uploads files. Learn more.

Learn more about the icons in the Snap settings dialog.


Field / Field set	Type	Description
Label	String	Required. Specify a unique name for the Snap. Modify this to be more appropriate, especially if there are more than one of the same Snap in the pipeline.
Schema Name	String/Expression	Specify the database schema name. In case it is not defined, then the suggestion for the Table Name retrieves all tables names of all schemas. The property is suggestible and will retrieve available database schemas during suggest values. Note: The values can be passed using the pipeline parameters but not the upstream parameter. Default value: N/A Example: Schema_demo
Table Name	String/Expression	Required. Specify the name of the table to execute Select query on. Default value: N/A Example: employees_table
Where Clause	String/Expression	Specify the where clause of the SELECT statement. This supports document value substitution (such as $person.firstname will be substituted with the value found in the incoming document at the path). Default value: N/A Example: ID in (48,50)
Order By	Use this fieldset to specify the columns in the order in which you want to sort the database. The default database sort order will be used.
Column names	String/Expression	Specify the column names. Default value: N/A Example: email
Time travel props	Use this field set to configure the time travel clause.
Key Columns	Dropdown list	Choose the key column for the query. The available options are: At Offset Before Statement Before Timestamp At Timestamp Before Offset Learn more about the time travel properties. Default value: N/A Example: email
Value Column	String/Expression	Specify the value for the corresponding key column. Default value: N/A Example: -60*5
Limit offset	Integer/Expression	Specify the offset for the limit clause. This is where the result set should start. Default value: N/A Example: 0
Limit rows	Integer/Expression	Specify the number of rows to return from the query. Default value: N/A Example: 10
Output fields	String/Expression	Enter or select output fields for Snowflake SQL SELECT statement. To select all fields, leave it at default. Default value: N/A Example: email
Fetch Output Fields In Schema	Checkbox	Select this checkbox to include only the selected fields or columns in the Output Schema (second output view). If you do not provide any Output fields, all the columns are visible in the output.If you provide output fields, we recommend you to select Fetch Output Fields In Schema checkbox. Default status: Deselected
Pass through	Checkbox	Select this checkbox to enable the Snap to pass the input document to the output view under the key named `original`. This option applies only to the Execute Snaps with SELECT statement. Default status: Selected
Ignore empty result	Checkbox	Select this checkbox to not write any document to the output view when a SELECT operation does not produce any result. If this checkbox is not selected and the Pass-through checkbox is selected, the input document is passed through to the output view. Default status: Deselected
Match data types	Checkbox	Conditional. This field applies only when the Output fields field is provided with any values. If this checkbox is selected, the Snap tries to match the output data types the same as when the Output fields property is empty (SELECT * FROM ...). The output preview would be in the same format as the one when SELECT * FROM is implied and all the contents of the table are displayed. Default status: Deselected
Number of retries	Integer/Expression	Specify the maximum number of attempts to be made to receive a response. The request is terminated if the attempts do not result in a response. If the value is larger than 0, the Snap first downloads the target file into a temporary local file. If any error occurs during the download, the Snap waits for the time specified in the Retry interval and attempts to download the file again from the beginning. When the download is successful, the Snap streams the data from the temporary file to the downstream Pipeline. All temporary local files are deleted when they are no longer needed. Minimum Value: 0 Note: Ensure that the local drive has sufficient free disk space to store the temporary local file. Default value: 0 Example: 3
Retry interval (seconds)	Integer/Expression	Specifies the time interval between two successive retry requests. A retry happens only when the previous attempt resulted in an exception. Default value: 1 Example: 10
Staging mode	Dropdown list	Required when the value in the Number of retries field is greater than 0. Specify the location from the following options to store input documents between retries: In memory: The query results are stored in the Snaplex memory. If the query is too large to fit in the memory space, it may cause the Snap to fail, choose the On disk option. On disk: The query results are stored on the disk in a temporary (tmp) directory that is managed by the SnapLogic platform. This directory is deleted automatically when the Snap terminates.
Handle Timestamp and Date Time Data	Dropdown list	Choose an option for handling timestamp and date time data. The available options are: Default Date Time format in UTC Time Zone: The Snowflake date time data are represented in UTC Time Zone. SnapLogic Date Time format in Regional Time Zone: The Snowflake date time data are represented in the same regional time zone value, as provided in the Snowflake account. Note: Recommendation: If you use the Timestamp TZ and Timestamp LTZ in this Snap, we recommend you to use SnapLogic Date Time format in Regional TimeZone to ensure that you get the Timestamp data output of the target table in the same format as in the source table. Source Table Target Table
Manage Queued Queries	Dropdown list	Default value: Select an option to determine whether the Snap should continue or cancel the execution of the queued Snowflake Execute SQL queries when you stop the pipeline. Note: If you select Cancel queued queries when the pipeline is stopped or if it fails, then the read queries under execution are canceled, whereas the write type of queries under execution are not canceled. Snowflake internally determines which queries are safe to be canceled and cancels those queries. Default value: Continue to execute queued queries when the pipeline is stopped or if it fails Example: Cancel queued queries when the pipeline is stopped or if it fails
Snap execution	Dropdown list	Choose one of the three modes in which the Snap executes. Available options are: Validate & Execute. Performs limited execution of the Snap and generates a data preview during pipeline validation. Subsequently, performs full execution of the Snap (unlimited records) during pipeline runtime. Execute only. Performs full execution of the Snap during pipeline execution without generating preview data. Disabled. Disables the Snap and all Snaps that are downstream from it.

Note:

For the Suggest in the Order by columns and the Output fields properties, the value of the Table name property should be an actual table name instead of an expression. If it is an expression, it will display an error message "Could not evaluate accessor: ..." when the 'Suggest' button is clicked. This is because, at the time the "Suggest" button is clicked, the input document is not available for the Snap to evaluate the expression in the Table name property. The input document is available to the Snap only during the preview or execution time.