# Data Catalog and crawlers

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This page was generated from content adapted from the [AWS Developer Guide](https://github.com/awsdocs/aws-glue-developer-guide.git)
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## AWS Glue databases

* **Note**\
  When you delete a database from the AWS Glue Data Catalog, all the tables in the database are also deleted.

## Adding classifiers to a crawler

* **Note**\
  If your data format is recognized by one of the built-in classifiers, you don't need to create a custom classifier.
* **Note**\
  If the built-in CSV classifier does not create your AWS Glue table as you want, you might be able to use one of the following alternatives:\
  Change the column names in the Data Catalog, set the `SchemaChangePolicy` to LOG, and set the partition output configuration to `InheritFromTable` for future crawler runs. Create a custom grok classifier to parse the data and assign the columns that you want. The built-in CSV classifier creates tables referencing the `LazySimpleSerDe` as the serialization library, which is a good choice for type inference. However, if the CSV data contains quoted strings, edit the table definition and change the SerDe library to `OpenCSVSerDe`. Adjust any inferred types to STRING, set the `SchemaChangePolicy` to LOG, and set the partitions output configuration to `InheritFromTable` for future crawler runs. For more information about SerDe libraries, see [SerDe Reference](https://docs.aws.amazon.com/athena/latest/ug/serde-reference.html) in the Amazon Athena User Guide.


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