[client-v2] Enum8/Enum16 insert accepts a non-member integer and uses Enum.ordinal(), silently storing values that are not enum members

Beginne in client-v2/src/main/java/com/clickhouse/client/api/data_formats/internal/SerializerUtils.java bei serializeEnumData() und lies anschließend die Validierungs- und Lookup-Methoden in ClickHouseEnum. Prüfe die vorhandenen Tests zur Enum-Serialisierung und ergänze Abdeckung für eine nicht enthaltene Number sowie eine Java-Enum-Konstante, deren Ordinalzahl vom deklarierten ClickHouse-Wert abweicht. Das Ziel ist erreicht, wenn ungültige Zahlen zurückgewiesen werden und Java-Enum-Namen den deklarierten Werten zugeordnet werden; führe die relevanten client-v2-Tests aus.

Description

SerializerUtils.serializeEnumData() validates only the String form of an Enum8/Enum16 value. The other two accepted forms are written to the wire unchecked:

• Number — ((Number) value).intValue() is written as-is, with no check that the integer is a declared member of the column's enum.
• Enum<?> — ((Enum<?>) value).ordinal() is written. Java's ordinal() is a 0-based declaration index and has nothing to do with the ClickHouse enum's declared numeric values, so a Java enum constant almost always maps to the wrong value (and typically to 0, which is usually not a member at all).

The server does not validate enum values on RowBinary input, so the row is accepted and stored. The invalid value then breaks reads: any text/JSON rendering of the column fails server-side with UNKNOWN_ELEMENT_OF_ENUM, and the row is effectively unrecoverable except by CAST(col, 'Int8').

Note the String path is already correct — ClickHouseEnum.value(String) throws IllegalArgumentException: Unknown enum name: .... This report is only about the numeric and Java-enum paths.

This is the clickhouse-java counterpart of https://github.com/ClickHouse/clickhouse-connect/issues/1156, where the same class of silent corruption happens (there via an unknown enum name defaulting to 0).

ClickHouse server version

26.10.3.7 (verified against a running server over HTTP).

Reproduction

TestNG test placed in client-v2/src/test/java/com/clickhouse/client/datatypes/:

package com.clickhouse.client.datatypes;

import com.clickhouse.client.api.Client;
import com.clickhouse.client.api.data_formats.RowBinaryFormatWriter;
import com.clickhouse.client.api.enums.Protocol;
import com.clickhouse.client.api.insert.InsertResponse;
import com.clickhouse.client.api.insert.InsertSettings;
import com.clickhouse.client.api.metadata.TableSchema;
import com.clickhouse.client.api.query.GenericRecord;
import com.clickhouse.data.ClickHouseFormat;
import org.testng.annotations.Test;

import java.util.UUID;
import java.util.concurrent.TimeUnit;

public class EnumInsertValidationTest {

    public enum Status { active, inactive }

    @Test
    public void enumInsertAcceptsNonMemberValues() throws Exception {
        Client client = new Client.Builder()
                .addEndpoint(Protocol.HTTP, "localhost", 8123, false)
                .setUsername("default").setPassword("")
                .setDefaultDatabase("default")
                .build();

        String table = "enum_validation_" + UUID.randomUUID().toString().replace('-', '_');
        client.execute("DROP TABLE IF EXISTS " + table).get(30, TimeUnit.SECONDS);
        client.execute("CREATE TABLE " + table
                + " (id UInt8, status Enum8('active' = 1, 'inactive' = 2)) ENGINE = Memory")
                .get(30, TimeUnit.SECONDS);

        TableSchema schema = client.getTableSchema(table);
        ClickHouseFormat format = ClickHouseFormat.RowBinary;

        // (a) integer that is not a member of the enum -- expected to be rejected
        try (InsertResponse r = client.insert(table, out -> {
            RowBinaryFormatWriter w = new RowBinaryFormatWriter(out, schema, format);
            w.setValue(schema.nameToColumnIndex("id"), 2);
            w.setValue(schema.nameToColumnIndex("status"), 7);
            w.commitRow();
        }, format, new InsertSettings()).get(30, TimeUnit.SECONDS)) {
            System.out.println("non-member int accepted, rows=" + r.getWrittenRows());
        }

        // (b) Java enum constant -- serialized via ordinal(), not via the declared value
        try (InsertResponse r = client.insert(table, out -> {
            RowBinaryFormatWriter w = new RowBinaryFormatWriter(out, schema, format);
            w.setValue(schema.nameToColumnIndex("id"), 3);
            w.setValue(schema.nameToColumnIndex("status"), Status.active);
            w.commitRow();
        }, format, new InsertSettings()).get(30, TimeUnit.SECONDS)) {
            System.out.println("Java enum accepted, rows=" + r.getWrittenRows());
        }

        for (GenericRecord rec : client.queryAll(
                "SELECT id, CAST(status, 'Int8') AS raw FROM " + table + " ORDER BY id")) {
            System.out.println("row id=" + rec.getInteger("id") + " raw=" + rec.getInteger("raw"));
        }

        // Reading the enum as text fails server-side: the stored values are not members.
        try {
            client.queryAll("SELECT toString(status) FROM " + table);
            System.out.println("text read OK");
        } catch (Exception e) {
            System.out.println("text read FAILED: " + e);
        }

        client.close();
    }
}

Actual output

non-member int accepted, rows=1
Java enum accepted, rows=1
row id=2 raw=7
row id=3 raw=0
text read FAILED: com.clickhouse.client.api.ClientException: Failed to get query response

7 is not a member of Enum8('active' = 1, 'inactive' = 2), and Status.active was written as 0 (its ordinal()) rather than as 1 (its declared value in the column). Both rows are stored, and reading the column as text then fails with UNKNOWN_ELEMENT_OF_ENUM on the server.

For contrast, the equivalent text-format insert is rejected by the server:

INSERT INTO t VALUES (2, 'Active')
-> Unknown element 'Active' for enum, maybe you meant: ['active']

Expected output

Both inserts should fail client-side with an error naming the column and the offending value, in the same style as the existing String path (IllegalArgumentException: Unknown enum name: Active), e.g.:

java.lang.IllegalArgumentException: Unknown enum value: 7

and Status.active should be written as the column's declared value for the name active (i.e. 1), or rejected if the name is not a member.

Suggested fix

client-v2/src/main/java/com/clickhouse/client/api/data_formats/internal/SerializerUtils.java, serializeEnumData() (around lines 863-872):

} else if (value instanceof Number) {
    enumValue = ((Number) value).intValue();   // not validated
} else if (value instanceof Enum<?>) {
    enumValue = ((Enum<?>)value).ordinal();    // ordinal != declared enum value
}

ClickHouseEnum already provides the needed checks and lookups:

• validate(int) — throws IllegalArgumentException("Unknown enum value: ..."); use it for the Number branch.
• value(String) — name to declared value; the Enum<?> branch should use column.getEnumConstants().value(((Enum<?>) value).name()) rather than ordinal().

It would also help to include the column name and original type name in the message, as the null check immediately above already does.

Link

Relayed from https://github.com/ClickHouse/clickhouse-connect/issues/1156
Central tracking issue: https://github.com/ClickHouse/integrations-ai-playground/issues/649