liquibase-core/src/main/java/liquibase/sqlgenerator/SqlGeneratorFactory.java
public boolean generateStatementsVolatile(SqlStatement statement, Database database) {
        for (SqlGenerator generator : getGenerators(statement, database)) {
            if (generator.generateStatementsIsVolatile(database)) {
                return true;
            }
        }
        return false;
    }
public boolean generateStatementsVolatile(SqlStatement statement, Database database) {
        for (SqlGenerator generator : getGenerators(statement, database)) {
            if (generator.generateStatementsIsVolatile(database)) {
                return true;
            }
        }
        return false;
    }
Return true if the SqlStatement class queries the database in any way to determine Statements to execute.
If the statement queries the database, it cannot be used in updateSql type operations