In Hibenate I am using MariaDB but I couldn't find the dialect class name of MariaDB .
In Hibernate, MySQL5 dialect's name is
<property name="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</property>
For Oracle 10g
<property name="hibernate.dialect">org.hibernate.dialect.Oracle10gDialect</property>
What is the dialect class name for MariaDB?
Very short answer
The current dialects as of this writing are:
org.hibernate.dialect.MariaDB102Dialect for MariaDB server 10.2
org.hibernate.dialect.MariaDB103Dialect for MariaDB server 10.3 and later, provides sequence support.
org.hibernate.dialect.MariaDB10Dialect for MariaDB server 10.0 and 10.1
org.hibernate.dialect.MariaDB53Dialect for MariaDB server 5.3, and later 5.x versions.
org.hibernate.dialect.MariaDBDialect for MariaDB server 5.1 and 5.2.
Short answer
When using a MariaDB server, you should use MariaDB Connector/J and MariaDB Hibernate dialects, not the MySQL ones. Even though MariaDB was created as a drop-in replacement and even though basic features will likely work when using the MySQL versions of those, subtle problems may occur or you may miss certain features.
A complete list of available MariaDB dialects are currently not mentioned in the Hibernate User Guide, but in the Hibernate JavaDoc. Depending on your MariaDB server version, you should select the corresponding dialect version. The current dialects as of this writing are:
org.hibernate.dialect.MariaDB102Dialect for MariaDB server 10.2
org.hibernate.dialect.MariaDB103Dialect for MariaDB server 10.3 and later, provides sequence support.
org.hibernate.dialect.MariaDB10Dialect for MariaDB server 10.0 and 10.1
org.hibernate.dialect.MariaDB53Dialect for MariaDB server 5.3, and later 5.x versions.
org.hibernate.dialect.MariaDBDialect for MariaDB server 5.1 and 5.2.
Note that for detailed usage information, you'll sometimes have to look in dialect source codes. (There are non-JavaDoc usage information comments in some dialect sources.)
If you want to change or explicitly mention the storage engine for the MariaDB dialect, you can use the storage_engine Hibernate variable. For example: hibernate.dialect.storage_engine = innodb. IMO, you should do this explicitly, because the default can change when switching to a different MariaDB server version.
If you're using a MariaDB server older than 10.1.2 (which doesn't support fractional seconds), then you may want to provide the parameter useFractionalSeconds=false to the JDBC URL, otherwise MariaDB Connector/J will not truncate timestamps internally, which can cause time comparison problem when those values are using in comparison queries (even when using plain JDBC), which can cause Hibernate versioning problems and optimistic locking problems for temporal types.
Long answer
The MariaDB dialect for Hibernate (5.3 as of this writing) is mentioned in the Hibernate User Guide. The mentioned dialect "short names" followed by remarks are:
MariaDB: Support for the MariadB database. May work with newer versions
MariaDB53: Support for the MariadB database, version 5.3 and newer.
However, a complete list of the available official MariaDB dialects can be found in the Hibernate JavaDoc. Which currently lists:
org.hibernate.dialect.MariaDB102Dialect for MariaDB server 10.2
org.hibernate.dialect.MariaDB103Dialect for MariaDB server 10.3 and later, provides sequence support.
org.hibernate.dialect.MariaDB10Dialect for MariaDB server 10.0 and 10.1
org.hibernate.dialect.MariaDB53Dialect for MariaDB server 5.3, and later 5.x versions.
org.hibernate.dialect.MariaDBDialect for MariaDB server 5.1 and 5.2.
Each dialect successor inherits the settings from the previous dialect version. So the inheritance hierachy for MariaDB is: MariaDB103Dialect > MariaDB102Dialect > MariaDB10Dialect > MariaDB53Dialect > MariaDBDialect > MySQL5Dialect > MySQLDialect > Dialect
MariaDB was designed as a drop-in replacement for MySQL. But the databases are likely going to diverge as time goes by. Most basic features probably work without problems, allowing you to swap Connector/J clients (MariaDB client on MySQL server and vice versa), and allow you to swap dialects (MySQL dialect on MariaDB client and vice versa). But there are subtle differences that may cause unexpected problems. For example, the MySQL Connector/J client contains hardcoded checks for the server version, which will fail when using a MariaDB server, causing some features to be disabled in the client, such as the MySQL sendFractionalSeconds client parameter. This will cause fractional seconds to be disabled, so then the fractions will be truncated in the MySQL client but not in the MariaDB client. (This may even lead to optimistic locking problems when using versioning with date/time types in combination with non-max precision SQL date/time types. In these cases, use the max precision of 6.)
Also, the MariaDB dialect are expected to provide specific functionality for MariaDB:
http://in.relation.to/2017/02/16/mariadb-dialects/
In time, we will add new Dialects based on newer capabilities
introduced by MariaDB.
...
If you are using MariaDB, it’s best to use the MariaDB-specific
Dialects from now on since it’s much easier to match the MariaDB
version with its appropriate Hibernate Dialect.
And https://hibernate.atlassian.net/browse/HHH-11457 says:
since MySQL and MariaDB have gone in different directions, we might
want to provide MariaDB Dialects as well.
For instance, it's not very intuitive for a Hibernate user to figure
out that they need to use the MySQLInnoDb57Dialect to handle
Timestamps with microsecond precision which have been available since
MariaDB 5.3:
The Hibernate User Guide doesn't provide all usage information about how to use the dialects. Even the User Guide combines with the API docs may not be enough. Sometimes you'll have to look in the source codes for usage information. For example, MariaDB53Dialect.java contains hidden non-JavaDoc comments that may be useful.
Previously, to select a MySQL storage engine, such as MyISAM or InnoDB or default, you could switch between for example MySQL57InnoDBDialect and MySQL57Dialect. But they refactored the MySQL dialect hierarchy starting from Hibernate 5.2.8, as mentioned in a Hibernate blog post. Note that to select a storage engine, you should use a Environment Variable or System Property: hibernate.dialect.storage_engine. For example: hibernate.dialect.storage_engine = innodb.
XtraDB was the default MariaDB storage engine for MariaDB 10.1 and earlier, but since 10.2 it's InnoDB. So there may be cases that you want to explicitly mention the storage engine that Hibernate selects, so then you'll have to use the storage_engine variable. Info about the storage_engine variable (which isn't mentioned in the User Guide), can be found in the source of AvailableSettings.java.
If you're using a MariaDB server older than 10.1.2 (which doesn't support fractional seconds), then you may want to provide the parameter useFractionalSeconds=false to the JDBC URL, otherwise MariaDB Connector/J will not truncate timestamps internally, which can cause time comparison problem, which can cause Hibernate versioning problems and optimistic locking problems for temporal types.
As announced here, starting with Hibernate ORM 5.2.8 (around Feb 15, 2017), the dialects
org.hibernate.dialect.MariaDB53Dialect
and
org.hibernate.dialect.MariaDBDialect
are available. The announcement concludes that
If you are using MariaDB, it’s best to use the MariaDB-specific
Dialects from now on since it’s much easier to match the MariaDB
version with its appropriate Hibernate Dialect.
From here, it was mentioned
"it needs to be the MySQL5InnoDBDialect or MySQL57InnoDBDialect instead of the MySQLInnoDBDialect"
For complete list, see
http://docs.jboss.org/hibernate/orm/5.2/userguide/html_single/Hibernate_User_Guide.html#database-dialect
New MariaDB dialect is added in 5.2.17. See JIRA and commit
You should use the Mysql5Dialect, because MariaDB is compatible with mysql.
https://mariadb.com/kb/en/mariadb-vs-mysql-compatibility/#incompatibilities-between-mariadb-55-and-mysql-55
Related
I have a spring boot application with mariaDB, after updating the connector ("org.mariadb.jdbc:mariadb-java-client") from version 2.7.5 to 3.0.3 the datetimes (LocalDateTime and ZonedDateTime) are using lower precision. In the database itself the columns are DATETIME(6) so they should be able to keep a precision of 6. But if I want to get a value from db the resulting LocalDateTime/ZonedDateTime only has a precison of 3.
Example:
I have an entity with timestamp 2022-03-14T08:59:33.893372.
I save it to the db. Get this entity back from db again. The timestamp from the entity out of the database will be 2022-03-14T08:59:33.893.
This leads into failing comparison of the two objects and also in failing tests.
The problem occures only if I use mariaDB connector 3.0.3. With version 2.7.5 everything works fine. I don't change any properties or something.
I am using spring-boot 2.6.4 with hibernate 5.6.5.Final and mariaDb server 10.6.
Why does this happen? Is there a way to get precision of 6 with updated mariaDb connector?
Thanks
I've got the same issue as yours :(
And found the connector issue https://jira.mariadb.org/browse/CONJ-947, which is fixed already.
The fix will be part of 3.0.5 version
I am facing this weird issue with spring Jdbc Template when used for Oracle DB.
JDK version- 11.0.3
ojdbc8 version- 12.2.0.1
Spring jdbc version-2.2.4.RELEASE
DB- Oracle- 12c
Issue:
When I call update() method on Jdbc Template, sometimes it does not return number of updated rows and returns '0' instead.
When I run same code with in memory db such as H2, it goes smooth.
I checked queries very closely and they are looking fine.
The issue was with the handling of the CHAR datatype in Oracle.
Oracle was doing right padding for this datatype and Jdbc query was failing for equality check cause of that(in SQL query 'WHERE' clause where I was using this field).
The use of RTRIM function in Query at the java side resolved this issue.
I'm working in a new project to convert our Delphi + Firebird system to Java 8 / JavaFX / JPA (Hibernate) and Firebird. We are using the latest version of Jaybird and connecting to Firebird 1.5, Firebird 3.0 and InterBase XE3 databases. I have not found any documentation on connecting to the DB specifying a DB role. Is there a way to do this?
To specify the user role, you need to specify the roleName property in the connection string. See also Extended connection properties in Jaybird JDBC Driver Java Programmer's Manual.
Example of a connection string:
jdbc:firebirdsql://localhost/database?charSet=UTF-8&roleName=myrole
I need suggestions/help on the issue below:
I am working on oracle migration work for a Java web application. I want to move my application from oracle 9i to 11g
The environment is :
Jdk – 1.4.2
Weblogic 8.1(SP6)
Database to connect to – Oracle 11g
weblogic.db.url=jdbc:oracle:thin:#${weblogic.db.host}:${weblogic.db.port}/
weblogic.db.driver=oracle.jdbc.OracleDriver
Oracle JDBC Driver version - "10.2.0.2.0"
When I query any table that has a CLOB datatype , the query fails to execute with the following error:
“Cannot assign value of type 'weblogic.jdbc.wrapper.Clob_oracle_sql_CLOB' to property 'description_en' of type 'oracle.sql.CLOB'”.
I have read in oracle docs that weblogic 8.1(S6) supports oracle 11g .
Any other query which returns other than CLOB data type, it works fine, the issue is only with CLOB datatype that too with Oracle 11g :(
The same code works fine if it is connected to Oracle 9i, the only problem is with Oracle 11g.
My assumption is that I may be missing some extra wrappers/extensions which may be needed to map the CLOB datatype as I think there is no direct support from weblogic 8.1.
I also am thinking on below lines:
If the application includes its own Oracle jar file so is not using the data source provided by WebLogic. But I do not know on how should I ascertain this.
Please help!
You need to upgrade your Java version. Java 1.4 is not supported by modern Oracle drivers.
Also, it is best practice to add the Oracle driver jars to the container classpath, and not include them in your application. Then the application needs to reference a datasource provided by the container. If you plan some Oracle-specific fireworks, you may need the driver jars at compile time. You need to mark them as "provided" in your Maven pom.xml.
I am writing a Java application using Hibernate and IBM DB2 9.7 LUW for database. I am using the SQLQuery API to read a custom SQL query string and execute it against the DB. The query contains aliases, i.e. SELECT WORK.EMPLOYEE AS WORKEMPLOYEE, just as an example.
When retrieving the result set from DB with list() command, the resulting map does not contain the alias as key. So writing map.containsKey("WORKEMPLOYEE") returns false. I also tried using query.setResultTransformer(AliasToEntityMapResultTransformer.INSTANCE) but it did not change the situation.
I don't know Hibernate, but I suspect this is a symptom of an issue we've seen regarding DB2 LUW and aliases.
It relates to the distinction between a column's "name" and its "label". IBM document the behaviour at this page, which suggests that the behaviour will be different with different versions of the database driver.
Specifically, this paragraph:
Whether a column in the SELECT list of a query has an AS clause. For JDBC drivers before the IBM Data Server Driver for JDBC and SQLJ Version 4.0, if a column in the SELECT list of a query contains an AS clause,ResultSetMetaData.getColumnNamereturns the argument of the AS clause. Under the IBM Data Server Driver for JDBC and SQLJ Version 4.0,ResultSetMetaData.getColumnNamereturns the table column name.
suggests that you are seeing the behaviour that you (and I) regard as faulty because you are using a version 4+ driver.
There are three possible solutions, none of which is entirely satisfactory.
Use a version 3.x driver.
You can switch to calling getColumnLabel on the ResultSetMetaData. That would give you the correct result with DB2 LUW using version 4+ drivers. This applies to our version of the problem, but might not be relevant or possible via Hibernate.
There is a property which you can set on the DataSource or Connection object: useJDBC4ColumnNameAndLabelSemantics would need to be set to DB2BaseDataSource.NO. However, I don't know whether you can set that via Hibernate. If you can, it should make aliases behave the old (and propert) way.
In our environment we haven't decided yet on how best to deal with this. We're working around it using option 1 for the moment. I'm inclined to use option 2, but we have to suport multiple DB platforms, and I'm not sure how it will work with the others. For option 3, we're sing Spring, so it may not be practical to set that property.