Redshift Data Share External Schema

Question

Hello,

I have created a data share in our redshift cluster and added schema/tables to it. To enable  dot notation I have created external schema in consumer cluster from Redshift DB  as: ```create external schema "external_schema_name" from redshift database 'db_ds' schema "schema_name";``` to query shared tables as

**external_schema_name.table_name**  
instead of

**shared_db_name.schema_name.table_name**

will cost of querying this external schema be same as querying spectrum ?

Answer

Hi Yasmeen,

Creating an external schema in Redshift does not always mean that Redshift Spectrum will be used. It depends on the FROM parameter; Redshift Spectrum is used to query data directly from files on an Amazon S3.

In your case, when you execute the  **create external schema ... from redshift ...** command, you are just mapping a data share schema to a local schema. This means both ways, with or without an external schema, will have the same cost which is, the producer cluster is charged for the data they shared and consumer clusters get charged for the compute they use in accessing the shared data.

Thanks,

Answer

Hello,

In this context I would like to inform you that with respect to Redshift spectrum pricing the main parameters that can incur costs are:
1. Volume of data scanned.
2. S3 storage.
3. S3 access requests made.

In case of data sharing, no additional cost is incurred to use the feature because no data is being scanned from S3 and no S3 storage is involved. You can securely share live data with Amazon Redshift clusters in the same or different AWS accounts, and across regions.

There will also be no additional cost for creating EXTERNAL SCHEMA, cost is incurred only when you scan data from AWS Glue data catalog, S3, KMS or any such resources.

Refer https://aws.amazon.com/redshift/pricing/  for more details on pricing.

Redshift Data Share External Schema

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