Question

I am designing a MySQL database which needs to handle about 600 row inserts per second across various InnoDB tables. My current implementation uses non-batched prepared statements. However, writing to the MySQL database bottlenecks and my queue size increases over time.

The implementation is written in Java, I don’t know the version off hand. It uses MySQL‘s Java connector. I need to look into switching to JDBC tomorrow. I am assuming these are two different connector packages.

I have read the following threads on the issue:

• Optimizing MySQL inserts to handle a data stream
• MyISAM versus InnoDB
• Inserting Binary data into MySQL (without PreparedStatement's)

and from the mysql site:

• http://dev.mysql.com/doc/refman/5.0/en/insert-speed.html

My questions are:

• Does anyone have advice or experience on performance differences using INSERTs with prepared statements in batch mode vs. using a single INSERT statement with multiple VALUEs.

• What are the performance differences between the MySQL Java connector vs. JDBC. Should I be using one or the other?

• The tables are for archive purposes, and will see ~90% write to ~10% read (maybe even less). I am using InnoDB. Is this the right choice over MyISAM?

Thank you in advance for your help.

Answer 1

JDBC is simply a Java SE standard of database access offering the standard interfaces so you’re not really bound to a specific JDBC implementation. MySQL Java connector (Connector/J) is an implementation of the JDBC interfaces for MySQL databases only. Out of experience, I’m involved to a project that uses huge amount of data using MySQL, and we mostly prefer MyISAM for data that can be generated: it allows to achieve much higher performance losing transactions, but generally speaking, MyISAM is faster, but InnoDB is more reliable.

I wondered for the performance of the INSERT statements too about a year ago, and found the following old testing code in my code shelf (sorry, it’s a bit complex and a bit out of your question scope). The code below contains examples of 4 ways of inserting the test data:

• single INSERTs;
• batched INSERTs;
• manual bulk INSERT (never use it – it’s dangerous);
• and finally prepared bulk INSERT).

It uses TestNG as the runner, and uses some custom code legacy like:

• the runWithConnection() method – ensures that the connection is closed or put back to the connection pool after the callback is executed (but the code below uses not reliable strategy of the statement closing – even without try/finally to reduce the code);
• IUnsafeIn<T, E extends Throwable> – a custom callback interface for the methods accepting a single parameter but potentially throwing an exception of type E, like: void handle(T argument) throws E;.

package test;

import test.IUnsafeIn;

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

import static java.lang.String.format;
import static java.lang.String.valueOf;
import static java.lang.System.currentTimeMillis;

import core.SqlBaseTest;
import org.testng.annotations.AfterSuite;
import org.testng.annotations.BeforeSuite;
import org.testng.annotations.BeforeTest;
import org.testng.annotations.Test;

public final class InsertVsBatchInsertTest extends SqlBaseTest {

    private static final int ITERATION_COUNT = 3000;

    private static final String CREATE_TABLE_QUERY = "CREATE TABLE IF NOT EXISTS ttt1 (c1 INTEGER, c2 FLOAT, c3 VARCHAR(5)) ENGINE = InnoDB";
    private static final String DROP_TABLE_QUERY = "DROP TABLE ttt1";
    private static final String CLEAR_TABLE_QUERY = "DELETE FROM ttt1";

    private static void withinTimer(String name, Runnable runnable) {
        final long start = currentTimeMillis();
        runnable.run();
        logStdOutF("%20s: %d ms", name, currentTimeMillis() - start);
    }

    @BeforeSuite
    public void createTable() {
        runWithConnection(new IUnsafeIn<Connection, SQLException>() {
            @Override
            public void handle(Connection connection) throws SQLException {
                final PreparedStatement statement = connection.prepareStatement(CREATE_TABLE_QUERY);
                statement.execute();
                statement.close();
            }
        });
    }

    @AfterSuite
    public void dropTable() {
        runWithConnection(new IUnsafeIn<Connection, SQLException>() {
            @Override
            public void handle(Connection connection) throws SQLException {
                final PreparedStatement statement = connection.prepareStatement(DROP_TABLE_QUERY);
                statement.execute();
                statement.close();
            }
        });
    }

    @BeforeTest
    public void clearTestTable() {
        runWithConnection(new IUnsafeIn<Connection, SQLException>() {
            @Override
            public void handle(Connection connection) throws SQLException {
                final PreparedStatement statement = connection.prepareStatement(CLEAR_TABLE_QUERY);
                statement.execute();
                statement.close();
            }
        });
    }

    @Test
    public void run1SingleInserts() {
        withinTimer("Single inserts", new Runnable() {
            @Override
            public void run() {
                runWithConnection(new IUnsafeIn<Connection, SQLException>() {
                    @Override
                    public void handle(Connection connection) throws SQLException {
                        for ( int i = 0; i < ITERATION_COUNT; i++ ) {
                            final PreparedStatement statement = connection.prepareStatement("INSERT INTO ttt1 (c1, c2, c3) VALUES (?, ?, ?)");
                            statement.setInt(1, i);
                            statement.setFloat(2, i);
                            statement.setString(3, valueOf(i));
                            statement.execute();
                            statement.close();
                        }
                    }
                });
            }
        });
    }

    @Test
    public void run2BatchInsert() {
        withinTimer("Batch insert", new Runnable() {
            @Override
            public void run() {
                runWithConnection(new IUnsafeIn<Connection, SQLException>() {
                    @Override
                    public void handle(Connection connection) throws SQLException {
                        final PreparedStatement statement = connection.prepareStatement("INSERT INTO ttt1 (c1, c2, c3) VALUES (?, ?, ?)");
                        for ( int i = 0; i < ITERATION_COUNT; i++ ) {
                            statement.setInt(1, i);
                            statement.setFloat(2, i);
                            statement.setString(3, valueOf(i));
                            statement.addBatch();
                        }
                        statement.executeBatch();
                        statement.close();
                    }
                });
            }
        });
    }

    @Test
    public void run3DirtyBulkInsert() {
        withinTimer("Dirty bulk insert", new Runnable() {
            @Override
            public void run() {
                runWithConnection(new IUnsafeIn<Connection, SQLException>() {
                    @Override
                    public void handle(Connection connection) throws SQLException {
                        final StringBuilder builder = new StringBuilder("INSERT INTO ttt1 (c1, c2, c3) VALUES ");
                        for ( int i = 0; i < ITERATION_COUNT; i++ ) {
                            if ( i != 0 ) {
                                builder.append(",");
                            }
                            builder.append(format("(%s, %s, '%s')", i, i, i));
                        }
                        final String query = builder.toString();
                        final PreparedStatement statement = connection.prepareStatement(query);
                        statement.execute();
                        statement.close();
                    }
                });
            }
        });
    }

    @Test
    public void run4SafeBulkInsert() {
        withinTimer("Safe bulk insert", new Runnable() {
            @Override
            public void run() {
                runWithConnection(new IUnsafeIn<Connection, SQLException>() {
                    private String getInsertPlaceholders(int placeholderCount) {
                        final StringBuilder builder = new StringBuilder("(");
                        for ( int i = 0; i < placeholderCount; i++ ) {
                            if ( i != 0 ) {
                                builder.append(",");
                            }
                            builder.append("?");
                        }
                        return builder.append(")").toString();
                    }

                    @SuppressWarnings("AssignmentToForLoopParameter")
                    @Override
                    public void handle(Connection connection) throws SQLException {
                        final int columnCount = 3;
                        final StringBuilder builder = new StringBuilder("INSERT INTO ttt1 (c1, c2, c3) VALUES ");
                        final String placeholders = getInsertPlaceholders(columnCount);
                        for ( int i = 0; i < ITERATION_COUNT; i++ ) {
                            if ( i != 0 ) {
                                builder.append(",");
                            }
                            builder.append(placeholders);
                        }
                        final int maxParameterIndex = ITERATION_COUNT * columnCount;
                        final String query = builder.toString();
                        final PreparedStatement statement = connection.prepareStatement(query);
                        int valueIndex = 0;
                        for ( int parameterIndex = 1; parameterIndex <= maxParameterIndex; valueIndex++ ) {
                            statement.setObject(parameterIndex++, valueIndex);
                            statement.setObject(parameterIndex++, valueIndex);
                            statement.setObject(parameterIndex++, valueIndex);
                        }
                        statement.execute();
                        statement.close();
                    }
                });
            }
        });
    }

}

Take a look at the methods annotated with the @Test annotation: they actually execute the INSERT statements. Also please take a look at the CREATE_TABLE_QUERY constant: in the source code it uses InnoDB producing the following results at my machine with MySQL 5.5 installed (MySQL Connector/J 5.1.12):

InnoDB
Single inserts: 74148 ms
Batch insert: 84370 ms
Dirty bulk insert: 178 ms
Safe bulk insert: 118 ms

If you change the CREATE_TABLE_QUERY InnoDB to MyISAM, you’d see significant performance increase:

MyISAM
Single inserts: 604 ms
Batch insert: 447 ms
Dirty bulk insert: 63 ms
Safe bulk insert: 26 ms

Hope this helps.

UPD:

For the 4th way you must properly customize the max_allowed_packet in mysql.ini (the [mysqld] section) to be large enough to support really big packets.