# Filtering results

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This page was generated from content adapted from the [AWS Developer Guide](https://github.com/awsdocs/amazon-personalize-developer-guide.git)
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## Filter expressions

* **Note**\
  Amazon Personalize ignores case only when matching event types.

## Filtering real-time recommendations

* **Note**\
  To filter recommendations using a filter with parameters and a campaign deployed before November 10, 2020, you must redeploy the campaign by using the [UpdateCampaign](https://github.com/kevinslin/aws-reference-notes/blob/main/services/amazon_personalize/API_UpdateCampaign.md) operation or create a new campaign.
* **Important**\
  For filter expressions that use an `INCLUDE` element to include items, you must provide values for all parameters that are defined in the expression. For filters with expressions that use an `EXCLUDE` element to exclude items, you can omit the `filter-values`. In this case, Amazon Personalize doesn't use that portion of the expression to filter recommendations.
* **Important**\
  You can't delete a filter while a batch inference job is in progress.
* **Important**\
  To filter recommendations using a filter with parameters and a campaign you deployed before November 10, 2020, you must re-deploy the campaign by using the [UpdateCampaign](https://github.com/kevinslin/aws-reference-notes/blob/main/services/amazon_personalize/API_UpdateCampaign.md) call or create a new campaign.
* **Important**\
  For filter expressions that use an `INCLUDE` element to include items, you must provide values for all parameters that are defined in the expression. For filters with expressions that use an `EXCLUDE` element to exclude items, you can omit the `filter-values`. In this case, Amazon Personalize doesn't use that portion of the expression to filter recommendations.
* **Important**\
  To filter recommendations using a filter with parameters and a campaign you deployed before November 10, 2020, you must re-deploy the campaign by using the [UpdateCampaign](https://github.com/kevinslin/aws-reference-notes/blob/main/services/amazon_personalize/API_UpdateCampaign.md) call or create a new campaign.
* **Important**\
  For filter expressions that use an `INCLUDE` element to include items, you must provide values for all parameters that are defined in the expression. For filters with expressions that use an `EXCLUDE` element to exclude items, you can omit the `filter-values`. In this case, Amazon Personalize doesn't use that portion of the expression to filter recommendations.