ELT Execute (Archived)
In this article
Overview
You can use this Snap to execute SQL queries in the target database—Snowflake, Redshift, Azure Synapse, Databricks Lakehouse Platform, or BigQuery. You can run the following types of queries using this Snap:
Data Definition Language (DDL) queries
Data Manipulation Language (DML) queries
Data Control Language (DCL) queries
Prerequisites
Valid accounts and access permissions to connect to the following:
Source: AWS S3, Azure Cloud Storage, or Google Cloud Storage
Target: Snowflake, Redshift, Azure Synapse, Databricks Lakehouse Platform, or BigQuery
If you want to use the COPY INTO command for loading data into the target database, you must pass (expose) these account credentials inside the SQL statement. Hence, we recommend you to consider using the ELT Load Snap as an alternative.
Limitations
This Snap does not support multi-statement transaction rollback of any of the DDL, DCL or DML statements specified.
Each statement is auto-committed upon successful execution. In the event of a failure, the Snap can rollback only updates corresponding to the failed statement execution. All previous statements (during that Pipeline execution runtime) that ran successfully are not rolled back.
You cannot run Data Query Language (DQL) queries using this Snap. For example,
SELECTandWITHquery constructs.Use this Snap either at the beginning or in the end of the Pipeline.
This Snap executes the SQL query only during Pipeline Execution. It does NOT perform any action (including showing a preview) during Pipeline validation.
ELT Snap Pack does not support Legacy SQL dialect of Google BigQuery. We recommend that you use only the BigQuery's Standard SQL dialect in this Snap.
Known Issues
ELT Pipelines created prior to 4.24 GA release using one or more of the ELT Insert Select, ELT Merge Into, ELT Load, and ELT Execute Snaps may fail to show expected preview data due to a common change made across the Snap Pack for the current release (4.26 GA). In such a scenario, replace the Snap in your Pipeline with the same Snap from the Asset Palette and configure the Snap's Settings again.
The Snap’s preview data (during validation) contains a value with precision higher than that of the actual floating point value (float data type) stored in the Delta. For example, 24.123404659344 instead of 24.1234. However, the Snap reflects the exact values during Pipeline executions.
In any of the supported target databases, this Snap does not appropriately identify nor render column references beginning with an _ (underscore) inside SQL queries that use the following constructs and contexts (the Snap works as expected in all other scenarios):
WHEREclauseWHENclauseONcondition (ELT Join, ELT Merge Into Snaps)HAVINGclauseQUALIFYclauseInsert expressions (column names and values in ELT Insert Select, ELT Load, and ELT Merge Into Snaps)
Update expressions list (column names and values in ELT Merge Into Snap)
Secondary
ANDconditionInside SQL query editor (ELT Select and ELT Execute Snaps)
As a workaround while using these SQL query constructs, you can:
Precede this Snap with an ELT Transform Snap to re-map the '_' column references to suitable column names (that do not begin with an _ ) and reference the new column names in the next Snap, as needed.
In case of Databricks Lakehouse Platform where CSV files do not have a header (column names), a simple query like
SELECT * FROM CSV.`/mnt/csv1.csv`returns default names such as _c0, _c1, _c2 for the columns which this Snap cannot interpret.To avoid this scenario, you can:
Write the data in the CSV file to a DLP table beforehand, as in:
CREATE TABLE csvdatatable (a1 int, b1 int,…) USING CSV `/mnt/csv1.csv`where a1, b1, and so on are the new column names.Then, read the data from this new table (with column names a1, b1, and so on) using a simple SELECT statement.
Snap Input and Output
Input | Document |
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| An upstream Snap is not mandatory. Use the input view to connect the Snap as the terminating Snap in the Pipeline. |
Output | Document |
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| A downstream Snap is not mandatory. Use the output view to connect the Snap as the first Snap in the Pipeline. |
Snap Settings
Label | String | Required. The 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. | N/A | ELT Execute for SF |
SQL Statements | Required. Use this field set to define your SQL statements, one in each row. Click to add a new row. You can add as many SQL statements as you need. | |||
SQL Statement Editor | String/Expression | Required. Enter the SQL statement to run, in this field. The SQL statement must follow the SQL syntax as stipulated by the target database—Snowflake, Redshift, Azure Synapse, or Databricks Lakehouse Platform. | N/A | drop table base_01_oldcodes; |
Troubleshooting
Failure: DQL statements are not allowed. | The ELT Execute Snap does not support Data Query Language (DQL) and hence statements containing | Remove any DQL statements (containing
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Examples
Sample Queries for the ELT Execute Snap
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CREATE OR REPLACE WAREHOUSE me_wh WITH warehouse_size='X-LARGE';
CREATE OR REPLACE TABLE "TEST_DATA".NEW_DATA(VARCHAR_DATA VARCHAR(10));
CREATE OR REPLACE TABLE "TEST_DATA".DT_EXECUTE_01(VARCHAR_DATA VARCHAR(100),TIME_DATA TIME,FLOAT_DATA FLOAT,BOOLEAN_DATA BOOLEAN,NUMBER_DATA NUMBER(38,0),DATE_DATA DATE);
TRUNCATE TABLE IF EXISTS "public".simple_data_02;
INSERT OVERWRITE INTO "BIGDATAQA"."TEST_DATA"."OUT_ELT_EXECUTE_SF_003" SELECT * FROM ( SELECT * FROM "BIGDATAQA"."TEST_DATA"."DT_EXECUTE_03" )Updating a Target Table Based on Updates to Another Table
The following Pipeline updates a target (backup) table - OUT_ELT_EXECUTE_SF_003 periodically based on the updates to another table DT_EXECUTE_03 (source). These tables are present in a Snowflake database, and we use data views from this database to present the updates that the Pipeline does in the target table.
There are two steps to achieve this functionality using the ELT Execute Snap:
Create a Pipeline with only the ELT Execute Snap for performing the periodic update.
Create a Scheduled Task from this Pipeline to trigger a job at specific times of the day, as needed. See Tasks Page for information on creating Scheduled Tasks from Pipelines.
This task regularly looks into the DT_EXECUTE_03 table for updates and inserts the latest data from this table into the target (backup) table.
Before we create the Pipeline:
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Target Table: OUT_ELT_EXECUTE_SF_003 |
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We configure the ELT Execute Snap to run a DML query, as follows.
Once we create the Scheduled Task (after saving this Pipeline), the task runs as scheduled. Then, the ELT Execute Snap copies the data from the source table and inserts into the target (backup) table.
After the Scheduled Task/Pipeline is run:
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Example 2: Using one ELT Execute Snap to Create and Fill a Table
In this example Pipeline, we create a new table in the Redshift database and fill data into this table using an ELT Execute Snap. We later read the data from this table using an ELT Select Snap.
Let us observe the configuration of the ELT Execute Snap (first Snap in the above Pipeline).
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Snap Output |
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We have added two SQL statements into the SQL Statements field set—one for creating/overwriting a table and another for inserting a row into same table. ELT Execute Snap does not have a data preview except for the placeholder SQL statement that indicates the Snap is validated successfully. The Snap executes the SQL queries real-time when we run the Pipeline.
We connect an ELT Select Snap to the ELT Execute Snap to read the data from the newly-created table in the Redshift database. In this Snap:
We use the same ELT Database account that we use for the previous Snap.
Define/select the values for the database, schema and the table name to identify the table that the previous Snap is configured to create.
Alternatively, we can enable the SQL query editor and include the
select * from dev.public.new_table_trg;statement.It is also important here to note that we cannot run this DQL query using the ELT Execute Snap.
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Snap Output |
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Downloads
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