db_schema.xml

<?xml version="1.0"?>
<!--
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
-->
<schema xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="urn:magento:framework:Setup/Declaration/Schema/etc/schema.xsd">
    <table name="inventory_low_stock_notification_configuration" resource="default" engine="innodb">
        <column xsi:type="varchar" name="source_code" nullable="false" length="255"/>
        <column xsi:type="varchar" name="sku" nullable="false" length="64"/>
        <column xsi:type="decimal" name="notify_stock_qty" scale="4" precision="12" unsigned="false" nullable="true"/>
        <constraint xsi:type="primary" referenceId="IDX_PRIMARY">
            <column name="source_code"/>
            <column name="sku"/>
        </constraint>
    </table>
</schema>