DatabaseMetaData methods do not normalize identifiers when lower_case_table_names=1 on MySQL 8.0

1. CONJ Issue: DatabaseMetaData methods do not normalize identifiers when lower_case_table_names=1 on MySQL 8.0

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1. 1. Title

DatabaseMetaData.getColumns() / getPrimaryKeys() fail to return correct results on MySQL 8.0 with lower_case_table_names=1

1. 1. Environment

• MariaDB Connector/J 2.7.2
• MySQL 8.0.46 (official, not MariaDB)
• lower_case_table_names=1
• OS: Amazon Linux 2 (EMR)
• JDK 8
• DataNucleus RDBMS 4.1.19 (Hive Metastore)

1. 1. Description

When MariaDB Connector/J connects to a MySQL 8.0 server configured with `lower_case_table_names=1`, the `DatabaseMetaData` methods (`getColumns()`, `getPrimaryKeys()`, `getTables()`, etc.) do not normalize table/schema name parameters to lowercase before querying `information_schema`.

On MySQL 8.0 with `lower_case_table_names=1`, all table names are stored as lowercase in the data dictionary and `information_schema`. While the query itself may still match (due to case-insensitive collation on information_schema columns), the *returned metadata column values* (e.g., `TABLE_NAME`, `COLUMN_NAME`) are all lowercase. This causes problems for ORM tools (like DataNucleus/JDO) that perform case-sensitive string comparison between the returned metadata identifiers and their internally-defined mapping names.

1. 1. Steps to Reproduce

1. Set up MySQL 8.0 with `lower_case_table_names=1`
2. Create a table: `CREATE TABLE PARTITION_KEYS (TBL_ID bigint PRIMARY KEY, ...);`
3. Connect with MariaDB Connector/J 2.7.2
4. Call `DatabaseMetaData.getColumns(catalog, null, "PARTITION_KEYS", "%")`
5. Iterate the ResultSet and check `rs.getString("COLUMN_NAME")`

*Expected*: Column names match the case used in CREATE TABLE or at minimum, the case passed as parameter (e.g., `TBL_ID`)

*Actual*: Column names are returned as lowercase (`tbl_id`) because MySQL 8.0 with `lower_case_table_names=1` stores identifiers in lowercase in its data dictionary, and the driver does not normalize/map them back.

1. 1. Impact

This breaks any framework that relies on case-sensitive matching of metadata column names against ORM mappings:

• Apache Hive Metastore (DataNucleus) fails with: `Table "partition_keys" has been specified with a primary-key to include column "TBL_ID" but this column is not found in the table.`
• Potentially affects any JPA/JDO tool using MariaDB Connector/J against MySQL 8.0 with `lower_case_table_names=1`

1. 1. Root Cause Analysis

In `MariaDbDatabaseMetaData.java`, the `patternCond()` helper method (line ~625 in 2.7.x) passes table name parameters directly to the SQL query without any case normalization:

```java
private boolean patternCond(
boolean firstCondition, StringBuilder sb, String columnName, String tableName) {
if (tableName == null || "%".equals(tableName))

{ return firstCondition; }

sb.append(firstCondition ? " WHERE " : " AND ")
.append(columnName)
.append((tableName.indexOf('%') == -1 && tableName.indexOf('_') == -1) ? "=" : " LIKE ")
.append("'")
.append(Utils.escapeString(tableName, true))
.append("'");
return false;
}
```

The connector already reads `@@lower_case_table_names` in `MariaDbConnection.getLowercaseTableNames()` (line ~1617), but this value is ONLY used for `storesLowerCaseIdentifiers()` / `supportsMixedCaseIdentifiers()` capability reporting – it is never applied in the actual metadata query methods.

1. 1. Suggested Fix

When `lower_case_table_names >= 1` on the server, normalize the catalog/schema/table name parameters to lowercase (using `Locale.ROOT`) before building the `information_schema` query. This is what MySQL Connector/J does via its `normalizeIdentifierCase()` method:

```java
// MySQL Connector/J approach (for reference)
String normalizeIdentifierCase(String identifier)

{ if (identifier == null) return null; return storesLowerCaseIdentifiers() ? identifier.toLowerCase(Locale.ROOT) : identifier; }

```

A similar normalization should be applied in MariaDB Connector/J's `patternCond()` and `catalogCond()` methods, or at the entry point of each metadata method.

1. 1. Affected Methods

• `getColumns()`
• `getPrimaryKeys()`
• `getTables()`
• `getImportedKeys()`
• `getExportedKeys()`
• `getCrossReference()`
• `getIndexInfo()`
• `getBestRowIdentifier()`

1. 1. Workaround

Replace MariaDB Connector/J with MySQL Connector/J 8.0.33+ when connecting to MySQL 8.0 with `lower_case_table_names=1`.