Catalog Query
- Subhajit Sengupta
- Mohammed Iqbal
- Lakshmi Manda
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Overview
The Catalog Query Snap enables you to read the metadata associated with a specific table in the SnapLogic data catalog.
Expected Input and Output
- Expected Input: A document stream containing information related to the metadata table that must be queried.
- Expected Output: A document stream containing the contents of the the metadata table that must be queried.
- Expected Upstream Snaps: Any Snap that offers document streaming data. Examples: Catalog Insert, Mapper.
- Expected Downstream Snaps: Required. Any Snap that accepts document streaming data in its input view. Examples: JSON Formatter, Catalog Insert.
Prerequisites
Read access to the SnapLogic metadata catalog.
Configuring Accounts
Accounts are not used with this Snap.
Configuring Views
Input | This Snap has at most one document input view. |
|---|---|
| Output | Required. This Snap has exactly one document output view. |
| Error | This Snap has at most one document error view. |
Troubleshooting
None.
Known Issues
- Does not work in Ultra pipelines.
Snap Settings
| Label | Required. The name for the Snap. Modify this to be more specific, especially if there are more than one of the same Snap in the pipeline. |
|---|---|
| Table Name | The location and name of the table that you want to query. Structure: /<Org>/<Project>/<Table_Name> Example: /TestOrg/shared/Docs_Test_Table Default value: None. |
| Partition Keys | The partition keys in the target table from which you want to extract metadata |
| Key Name | The key you want to use to query a specific partition in a metadata table. Example: airline_code Default value: None |
| Operator | The operator that you want to use in the condition required to locate the table partition. Example: != Default value: = |
| Key Value | The value that you want to use in the condition required to locate the table partition. Example: 10 Default value: None |
Snap Execution | Select one of the following three modes in which the Snap executes:
Default Value: Execute only |
Examples
Inserting and Querying Custom Metadata from the Flight Metadata Table
The Pipeline in this zipped example, MetadataCatalog_Insert_Read_Example.zip, demonstrates how you can:
- Use the Catalog Insert Snap to update metadata tables.
- Use the Catalog Query Snap to read the updated metadata information.
In this example:
- We import a file containing the metadata.
- We create a parquet file using the data in the imported file
- We insert metadata that meets specific requirements into a partition in the target table.
- We read the newly-inserted metadata using the Catalog Query Snap.
The Pipeline is designed as follows:
The File Reader Snap read flight statistics and the JSON Parser Snap parses the data into a JSON file.
The Parquet Writer Snap creates a Parquet file with the data of the JSON file, in an S3 database.
The output of the Parquet Writer Snap includes the schema of the file. This is the metadata that must be included into the catalog.
The Catalog Insert Snap picks up the schema from the Parquet file and associates it with a specific partition in the target table. It also adds a custom property to the partition.
Once the Snap completes execution, the table is inserted into the metadata catalog and you can view the table in the SnapLogic Manager.
To view the table, navigate to the Project where you have created the Pipeline, click the Table tab, and then click the new table created after executing the Pipeline. This displays the table. Click Show schema to view the metadata.
The Schema view does not display the custom metadata that you inserted into the partition. Use the Catalog Query Snap to view all the updates made by the Catalog Insert Snap.
Download this ZIP file.
Working with the Sample ZIP File
This ZIP file contains two files:
- Metadata_Catalog_Insert_Read.slp
- AllDataTypes.json
To import this Pipeline:
- Download the ZIP file and extract its contents into a local directory.
- Import the Metadata_Catalog_Insert_Read.SLP Pipeline into a SnapLogic project.
- Open the Pipeline and click the File Reader Snap.
- In the File Reader Settings popup, use the
button to import and read the AllDataTypes.json file. - Your Pipeline and test data are now ready. Review the other steps listed out in this example before validating or executing this Pipeline.
Downloads
Important steps to successfully reuse Pipelines
- Download and import the pipeline into the SnapLogic application.
- Configure Snap accounts as applicable.
- Provide pipeline parameters as applicable.
Snap Pack History
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