I attached my test class. It always results with test.trace.db file created
(somewhere around 7500 iteration).
MM
W dniu wtorek, 26 marca 2013 14:21:15 UTC+1 użytkownik Michał Michalak
napisał:
>
> Hello
>
> I am using Java with H2 to store serialized objects. Application stores
> many small data chunks (1kB) but it happens from time to time that data
> chuck size is quite large (20MB) - rarely but it happens. This is stored in
> table with int id and blob column for data. I am using H2 version 1.3.170
> (Maven repository) to start embedded database that uses file on disk.
>
> I noticed that "trace.db" file appears couple of minutes after application
> start with message:
> pageStore: Transaction log could not be truncated; size: 16 MB
>
> When creating new H2 connection I always set auto commit to true. I also
> make sure to close statement after each insert and select using Java7
> autoclose mechanizm try(){}. Is there anything more I could do to avoid
> this warning. And another question is, does this affect any data stored in
> database?
>
> Regards
> M.Michalak
>
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package ___mm___;
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.sql.Statement;
import javax.sql.rowset.serial.SerialBlob;
public class H2TraceFile {
private static final int FILES_NUMBER = 10000;
private static final int STRING_SIZE = 10000;
private static final int STRING_SIZE_BIG = 30000000;
private static String testString;
private static String testStringBig;
static {
StringBuilder sb = new StringBuilder();
while (sb.length() < STRING_SIZE) {
sb.append("hello world!");
}
testString = sb.toString();
while (sb.length() < STRING_SIZE_BIG) {
sb.append("hello big world!");
}
testStringBig = sb.toString();
}
public static void main(String[] args) throws Exception {
new H2TraceFile().startTest();
}
private void startTest() throws SQLException, IOException {
// Make sure there is no old test db file.
Files.deleteIfExists(new File("test.h2.db").toPath());
Files.deleteIfExists(new File("test.lock.db").toPath());
Files.deleteIfExists(new File("test.trace.db").toPath());
// Create connection.
try (Connection h2Connection = DriverManager.getConnection("jdbc:h2:test", "sa", "")) {
h2Connection.setAutoCommit(true);
// Create new table.
try (Statement statement = h2Connection.createStatement()) {
boolean resultCreateTable = statement.execute("CREATE TABLE JOB_DATA (ID BIGINT, DATA IMAGE)");
if (resultCreateTable) {
// Should never happen.
System.out.println("Create table, failed.");
} else {
// Create unique marker.
resultCreateTable = statement.execute("ALTER TABLE JOB_DATA ADD UNIQUE (ID)");
if (resultCreateTable) {
System.out.println("Create table, done. Make ID unique, failed.");
} else {
System.out.println("Create table, done. Make ID unique, done.");
}
}
}
// Store data.
for (int i = 0; i < FILES_NUMBER; i++) {
boolean isSmall = i % 10 != 0;
String sqlQuery = "INSERT INTO JOB_DATA VALUES(?, ?)";
try (PreparedStatement statement = h2Connection.prepareStatement(sqlQuery)) {
statement.setLong(1, i);
if (isSmall) {
statement.setBlob(2, new SerialBlob(testString.getBytes()));
} else {
statement.setBlob(2, new SerialBlob(testStringBig.getBytes()));
}
int rowsChanged = statement.executeUpdate();
if (rowsChanged < 1) {
throw new SQLException("Add data, failure. Nothing inserted.");
}
}
System.out.println("Done: " + i + (isSmall ? "" : " BIG"));
}
}
}
}
