6 files declare their use of SchemaException

DriverSpecificSchemaTestBase.php in core/tests/Drupal/KernelTests/Core/Database/DriverSpecificSchemaTestBase.php
Schema.php in core/modules/mysql/src/Driver/Database/mysql/Schema.php
SchemaTableColumnSizeTooLargeException.php in core/lib/Drupal/Core/Database/Exception/SchemaTableColumnSizeTooLargeException.php
SchemaTableKeyTooLargeException.php in core/lib/Drupal/Core/Database/Exception/SchemaTableKeyTooLargeException.php
SchemaTest.php in core/modules/mysql/tests/src/Kernel/mysql/SchemaTest.php
SqlContentEntityStorage.php in core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php

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