---
title: Why do I have to drop the blink attribute and re-add it to create a partitioned blink table?
sidebar_label: How do I create a partitioned blink table?
---

<em>I can create a partitioned blink table, but why do I have to drop the blink attribute and re-add it to do so?</em>

<p></p>

Aggregations on blink tables are defined to act as if you had full history from the time of operation instantiation. For example, if you use [`last_by`](../table-operations/group-and-aggregate/lastBy.md) on a [blink table](../../conceptual/table-types.md#specialization-3-blink), you get the last `n` rows for each bucket, considering all rows that have ever been processed by the operation since it was created - even if those rows are no longer part of the current update cycle. Deephaven does not allow users to perform operations that can't deliver those semantics - meaning [`group_by`](../table-operations/group-and-aggregate/groupBy.md), [`partition_by`](../table-operations/group-and-aggregate/partitionBy.md), and [rollup tables](../table-operations/create/rollup.md) with constituents will not work.

To get around these restrictions, you can use [`remove_blink`](../table-operations/create/remove-blink.md) to opt out of special semantics. Then, you can use [`partition_by`](../table-operations/group-and-aggregate/partitionBy.md) to get a result with constituents that will blink in and out of existence.

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