ELT Load
In this article
- 1 Overview
- 1.1 Snap Type
- 1.2 Prerequisites
- 1.3 Limitations
- 1.4 Known Issues
- 2 Snap Views
- 3 Snap Settings
- 4 Snap Behavior During Pipeline Validation
- 5 Troubleshooting
- 6 Examples
- 6.1 Loading Files from S3 Bucket to Snowflake
- 6.2 Uploading data from a CSV File in Azure Data Lake Gen2 Storage to Azure Synapse
- 6.3 Load data from a canonical format Parquet file
- 6.4 Load data from a non-canonical format Parquet file
- 6.5 Load flat data from Parquet files in Azure Blob Storage to a DLP table
- 6.6 Downloads
- 7 Snap Pack History
Overview
You can use this Snap to load files/data from Amazon S3 buckets or Azure Cloud Storage containers to a Snowflake, Azure Synapse database, or a Databricks Lakehouse Platform (DLP) instance. You can also use this Snap to load or transfer data from:
Amazon S3 buckets to the Amazon Redshift database.
Amazon Redshift or Google Cloud Storage to BigQuery tables.
A DBFS folder to a DLP table.
Refer to ELT Source-Target-Hosting Support Matrix for complete information.
If you want to use the COPY INTO command in ELT Execute Snap for loading data into the target database, you need to pass (expose) these account credentials inside the SQL statement. You can use the ELT Load Snap to prevent this security issue.
Snap Type
The ELT Load Snap is a Write-type Snap that writes/loads data from a source file/table to a table in the destination/target CDW.
Prerequisites
Valid accounts and access permissions to connect to one source and one target in the following source and target locations (Refer to the ELT Source-Target-Hosting Support Matrix for the supported source-target combinations):
Source: Amazon S3, Azure Cloud Storage, DBFS location, or Google Cloud Storage
Target: Snowflake, Redshift, Azure Synapse, DLP, or BigQuery
Limitations
Known Issues
Snap Views
Type | Format | Number of Views | Examples of Upstream and Downstream Snaps | Description |
|---|---|---|---|---|
Input | Document |
|
| A document containing the SQL query that you can use from the upstream ELT Snaps. |
Output | Document |
|
| A document containing the status of the load operation and an SQL query that you can use in any downstream ELT Snaps. |
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 by choosing one of the following options from the When errors occur list under the Views tab:
Learn more about Error handling in pipelines. | |||
Snap Settings
Asterisk ( * ): Indicates a mandatory field.
Suggestion icon (): Indicates a list that is dynamically populated based on the configuration.
Expression icon ( ): Indicates the value is an expression (if enabled) or a static value (if disabled). Learn more about Using Expressions in SnapLogic.
Add icon ( ): Indicates that you can add fields in the field set.
Remove icon ( ): Indicates that you can remove fields from the field set.
Upload icon ( ): Indicates that you can upload files.
SQL Functions and Expressions for ELT
You can use the SQL Expressions and Functions supported for ELT to define your Snap or Account settings with the Expression symbol ( ) enabled, where available. This list is common to all supported target CDWs. You can also use other expressions/functions that your target CDW supports.
Field Name | Field Type | Field Dependency | Description | |
|---|---|---|---|---|
Label*
Default Value: ELT Load Example: S3 Load | String | None. | Specify a name for the Snap. You can modify this to be more specific, especially if you have more than one of the same Snap in your pipeline.
| |
Get preview data
Default Value: Not selected Example: Selected | Checkbox | None. | Select this checkbox to include a preview of the query's output. The Snap performs limited execution and generates a data preview during pipeline validation. For ELT pipelines, only the SQL query flows through the Snaps but not the actual source data. Therefore, the preview data for a Snap is the result of executing the SQL query that the Snap has generated in the pipeline. The number of records displayed in the preview (on validation) is the smaller of the following:
Rendering Complex Data Types in DLP Based on the data types of the fields in the input schema, the Snap renders the complex data types such as map and struct as object data type and array as an array data type. It renders all other incoming data types as-is except for the values in binary fields are displayed as a base64 encoded string and as string data type. | |
Database Name
Default Value: N/A Example: TEST_DB | String | None. | Enter the name of the database in which the target table exists. Leave this blank if you want to use the database name specified in the Default Database Name field in the Account settings. | |
Schema Name (Not applicable to Databricks Lakehouse Platform)*
Default Value: N/A Example: SALES | String | Not applicable to DLP. | Enter the name of the database schema. In case the schema name is not defined, then the suggestions retrieved for the schema name contain all schema names in the specified database.
| |
Target Table Name*
Default Value: N/A Example: SALES_ORDERS | String | None. | Enter the name of the table or view in which you want to perform the load operation. Only views that can be updated (have new rows) are listed as suggestions. So, Join views are not included. This also implies that the Snap account user has the Insert privileges on the views listed as suggestions.
| |
Target Table Hash Distribution Column (Azure Synapse Only)
Default Value: N/A Example: Var_table | String/Expression | Applicable to Azure Synapse only. | Specify the hash distribution column name for the target table in Azure Synapse, if you choose the Load Action as Drop and Create table. Azure Synapse needs a table to be always hash-distributed for improved query performance. If the target table is created outside the Snap, you need not specify the target table column name here. | |
Load Action
Default Value: Append rows to existing table Example: Alter table | Dropdown list | None. | Select the load action to perform on the target table. Available options are:
The Snap does not modify the existing tables during pipeline validation, but if you choose the Drop and Create table option in the Load Action field and the target table does not exist, it creates a new (empty) target table based on the schema specified in the Snap. | |
Table Columns | This field set enables you to configure the schema of the target table. You can use this field set to add/drop columns in the target table if you select the Drop and Create table or Alter table options in the Load Action field. This field set consists of the following fields:
| |||
Column
Default Value: N/A Example: ID, FNAME | String | Load Action is Drop and Create table or Alter table. | Enter the name of the column that you want to load in the target table. You can also specify the columns to drop if you select the Alter table option in the Load Action field. | |
Data Type
Default Value: N/A Example: INT, VARCHAR | String | Load Action is Drop and Create table or Alter table. | Enter the data type of the values in the specified column. Use the VARIANT data type for target table columns that correspond to a map (JSON OBJECT) or array (JSON LIST) in your nested Parquet files. | |
Modifier
Default Value: Add Example: Drop | String | Load Action is Alter table. | Select whether you want to add/drop the specified column. Available options are:
| |
Table Option List | This field set enables you to define the table options for creating the target table before performing the load operation. These options vary based on your target CDW. Refer to the Table options for Load action for the complete list of permitted table options. You must specify each table option in a separate row.
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Table Option
Default Value: N/A Example: OPTIONS(custID=03761) | Expression/Suggestion |
| Choose a table option that you want to use from the suggested options. Specify the required values for the selected option. | |
Redshift Schema Name (Only when BigQuery with Source Location as Redshift)
Default Value: N/A Example: PUBLIC, DEF_SCHEMA | String/Expression | Database Type is BigQuery and Source Location is Amazon Redshift in the Snap Account. | Specify the schema name of the source table in Redshift. | |
Redshift Table Name (Only when BigQuery with Source Location as Redshift)
Default Value: N/A | ||||
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