| <a id="tf11631"></a>**11631** | An `ALTER INDEX ... REORGANIZE` and the [background merge task](../../relational-databases/indexes/columnstore-indexes-overview.md#bckmergetsk) clean up the deleted rows in a columnstore index rowgroup only when a certain threshold of rows has been deleted from that rowgroup. The default threshold is 10% of the maximum row limit (1 million), or of 100,000 rows.<br /><br />This trace flag changes the threshold to 10% of the total current rows in a columnstore rowgroup. For example, if a rowgroup contains 20,000 rows, the threshold is 2,000 deleted rows before this rowgroup is considered for cleanup. For more information, see [KB5000895](https://support.microsoft.com/kb/5000895).<br /><br />**Applies to:** [!INCLUDE [sql-server-2019](../../includes/sssql19-md.md)] CU 9 and later versions.<br /><br />**Scope:** Global only. |
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