H2Database.java

/*-
 * ========================LICENSE_START=================================
 * flyway-core
 * ========================================================================
 * Copyright (C) 2010 - 2026 Red Gate Software Ltd
 * ========================================================================
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * =========================LICENSE_END==================================
 */
package org.flywaydb.core.internal.database.h2;

import org.flywaydb.core.api.MigrationVersion;
import org.flywaydb.core.api.configuration.Configuration;
import org.flywaydb.core.internal.database.base.Database;
import org.flywaydb.core.internal.database.base.Table;
import org.flywaydb.core.internal.exception.FlywaySqlException;
import org.flywaydb.core.internal.jdbc.JdbcConnectionFactory;
import org.flywaydb.core.internal.jdbc.StatementInterceptor;

import java.sql.Connection;
import java.sql.SQLException;

public class H2Database extends Database<H2Connection> {
    /**
     * A dummy user used in Oracle mode, where USER() can return null but nulls can't be inserted into the schema
     * history table
     */
    private static final String DEFAULT_USER = "<< default user >>";
    /**
     * A dummy script marker used in Oracle mode, where a marker row is inserted with no corresponding script.
     */
    private static final String DUMMY_SCRIPT_NAME = "<< history table creation script >>";

    /**
     * The compatibility modes supported by H2. See http://h2database.com/html/features.html#compatibility
     */
    private enum CompatibilityMode {
        REGULAR,
        STRICT,
        LEGACY,
        DB2,
        Derby,
        HSQLDB,
        MSSQLServer,
        MariaDB,
        MySQL,
        Oracle,
        PostgreSQL,
        Ignite
    }

    boolean supportsDropSchemaCascade;
    private boolean requiresV2MetadataColumnNames;
    CompatibilityMode compatibilityMode;

    public H2Database(final Configuration configuration,
        final JdbcConnectionFactory jdbcConnectionFactory,
        final StatementInterceptor statementInterceptor) {
        super(configuration, jdbcConnectionFactory, statementInterceptor);

        requiresV2MetadataColumnNames = super.determineVersion().isAtLeast("2.0.0");
        compatibilityMode = determineCompatibilityMode();
    }

    @Override
    protected H2Connection doGetConnection(final Connection connection) {
        return new H2Connection(this, connection, requiresV2MetadataColumnNames);
    }

    @Override
    protected MigrationVersion determineVersion() {
        final String query = requiresV2MetadataColumnNames
            ? "SELECT SETTING_VALUE FROM INFORMATION_SCHEMA.SETTINGS WHERE SETTING_NAME = 'info.BUILD_ID'"
            : "SELECT VALUE FROM INFORMATION_SCHEMA.SETTINGS WHERE NAME = 'info.BUILD_ID'";
        try {
            final int buildId = getMainConnection().getJdbcTemplate().queryForInt(query);
            return MigrationVersion.fromVersion(super.determineVersion().getVersion() + "." + buildId);
        } catch (SQLException e) {
            throw new FlywaySqlException("Unable to determine H2 build ID", e);
        }
    }

    private CompatibilityMode determineCompatibilityMode() {
        final String query = requiresV2MetadataColumnNames
            ? "SELECT SETTING_VALUE FROM INFORMATION_SCHEMA.SETTINGS WHERE SETTING_NAME = 'MODE'"
            : "SELECT VALUE FROM INFORMATION_SCHEMA.SETTINGS WHERE NAME = 'MODE'";
        try {
            final String mode = getMainConnection().getJdbcTemplate().queryForString(query);
            if (mode == null || "".equals(mode)) {
                return CompatibilityMode.REGULAR;
            }
            return CompatibilityMode.valueOf(mode);
        } catch (SQLException e) {
            throw new FlywaySqlException("Unable to determine H2 compatibility mode", e);
        }
    }

    @Override
    public void ensureSupported(final Configuration configuration) {
        ensureDatabaseIsRecentEnough("1.2.137");
        recommendFlywayUpgradeIfNecessary("2.3.232");
        supportsDropSchemaCascade = getVersion().isAtLeast("1.4.200");
    }

    @Override
    public String getRawCreateScript(final Table table, final boolean baseline) {
        // In Oracle mode, empty strings in the marker row would be converted to NULLs. As the script column is
        // defined as NOT NULL, we insert a dummy value when required.
        final String script = (compatibilityMode == CompatibilityMode.Oracle) ? DUMMY_SCRIPT_NAME : "";

        return "CREATE TABLE IF NOT EXISTS "
            + table
            + " (\n"
            + "    \"installed_rank\" INT NOT NULL,\n"
            + "    \"version\" VARCHAR(50),\n"
            + "    \"description\" VARCHAR(200) NOT NULL,\n"
            + "    \"type\" VARCHAR(20) NOT NULL,\n"
            + "    \"script\" VARCHAR(1000) NOT NULL,\n"
            + "    \"checksum\" INT,\n"
            + "    \"installed_by\" VARCHAR(100) NOT NULL,\n"
            + "    \"installed_on\" TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,\n"
            + "    \"execution_time\" INT NOT NULL,\n"
            + "    \"success\" BOOLEAN NOT NULL,\n"
            + "    CONSTRAINT \""
            + table.getName()
            + "_pk\" PRIMARY KEY (\"installed_rank\")\n"
            + ")"
            +
            // Add special table created marker to compensate for the inability of H2 to lock empty tables
            " AS SELECT -1, NULL, '<< Flyway Schema History table created >>', 'TABLE', '"
            + script
            + "', NULL, '"
            + getInstalledBy()
            + "', CURRENT_TIMESTAMP, 0, TRUE;\n"
            + (baseline ? getBaselineStatement(table) + ";\n" : "")
            + "CREATE INDEX \""
            + table.getSchema().getName()
            + "\".\""
            + table.getName()
            + "_s_idx\" ON "
            + table
            + " (\"success\");";
    }

    @Override
    public String getSelectStatement(final Table table) {
        return "SELECT "
            + quote("installed_rank")
            + ","
            + quote("version")
            + ","
            + quote("description")
            + ","
            + quote("type")
            + ","
            + quote("script")
            + ","
            + quote("checksum")
            + ","
            + quote("installed_on")
            + ","
            + quote("installed_by")
            + ","
            + quote("execution_time")
            + ","
            + quote("success")
            + " FROM "
            + table
            // Ignore special table created marker
            + " WHERE "
            + quote("type")
            + " != 'TABLE'"
            + " AND "
            + quote("installed_rank")
            + " > ?"
            + " ORDER BY "
            + quote("installed_rank");
    }

    @Override
    protected String doGetCurrentUser() throws SQLException {
        try {
            String user = getMainConnection().getJdbcTemplate().queryForString("SELECT USER()");
            if (compatibilityMode == CompatibilityMode.Oracle && (user == null || "".equals(user))) {
                user = DEFAULT_USER;
            }
            return user;
        } catch (Exception e) {
            if (compatibilityMode == CompatibilityMode.Oracle) {
                return DEFAULT_USER;
            }
            throw e;
        }
    }

    @Override
    public boolean supportsDdlTransactions() {
        return false;
    }

    @Override
    public String getBooleanTrue() {
        return "1";
    }

    @Override
    public String getBooleanFalse() {
        return requiresV2MetadataColumnNames ? "FALSE" : "0";
    }

    @Override
    public boolean catalogIsSchema() {
        return false;
    }
}