![]() ![]() You can earn a significant passive income stream from promoting all these amazing products that I have been creating. If you enjoyed this article, I bet you are going to love my Book and Video Courses as well. Notice that this time, the TxId entry is added for each SQL statement executed after setting the txId MDC log variable. WARN : TxId: o.h.e.j.s.SqlExceptionHelper -ĮRROR : TxId: o.h.e.j.s.SqlExceptionHelper -Īs I explained in this article, the SELECT CAST(txid_current() AS text) is used in PostgreSQL to get the underlying database transaction identifier. When running the test case above, Hibernate is going to generate the following log entries:ĭEBUG : TxId: n.t.d.l.SLF4JQueryLoggingListener. This way, we make sure the txId variable is removed from the MDC storage so that it will not be appended to the log after exiting the try-with-resources block. Notice that we are using the MDC.putCloseable method in a try-with-resources block. contains("could not obtain lock on row in relation") Now, we can modify the previous test case to include the MDC txId log variable: Logging the identifier of the current database transaction The %X pattern is used to reference the txId log variable. To print the “txId” log variable to the log, we need to include this variable in the log appender pattern: ![]() For more details, check out this article. To get the identifier of the underlying database transaction, you need to use a database-specific query. MDC.put("txId", String.format(" TxId: ", transactionId(entityManager))) So, to set a given log variable using MDC, you can the put method as illustrated by the following example: Since SLF4J (Simple Logging Facade) is a very convenient Java logging adaptor, it has become a very popular choice for many Java applications, and it also provides support for MDC via the class. Basically, MDC allows you to register key/value pairs that are confined to the currently running thread and which you can reference when the logging framework builds log messages. MDC (Mapped Diagnostic Context) is for logging what ThreadLocal is to Java threads. Now, we want to append the database transaction identifier to the SQL statement log messages so that we can correlate the executed SQL queries with their associated transactions.įor this purpose, we can use MDC. Notice that the second query has a Success status of False since an SQLException is thrown with the could not obtain lock on row in relation "post" message. WARN : o.h.e.j.s.SqlExceptionHelper -ĮRROR : o.h.e.j.s.SqlExceptionHelper -ĮRROR: could not obtain lock on row in relation "post" When running the aforementioned test case, Hibernate generates the following log entries:ĭEBUG : n.t.d.l.SLF4JQueryLoggingListener. Afterward, the second user, Bob, tries to lock the same post record, but since he uses the NO_WAIT lock directive, he will get a LockAquisitionException right away.įor more details about the SQL NOWAIT clause, check out this article. The first user, Alice, locks the post record with the identifier value of 1. "could not obtain lock on row in relation" Post _post = (Post) _entityManager.createQuery(""" setLockMode(LockModeType.PESSIMISTIC_WRITE) Post post = entityManager.createQuery(""" Now, let’s assume we have the following situation: Guide to logging database transaction id with a SQL statement using the MDC (Mapped Diagnostic Context) feature. Since JPA and Hibernate generate SQL statements on your behalf based on the entity state transitions executed by the data access layer, using logging is mandatory as you need to acknowledge that the auto-generated SQL statements are both effective and efficient. For more details, check out the Hypersistence Utils open-source project. With datasource-proxy, you can easily build a JUnit extension to automatically detect N+1 query issues. As I explained in this article, using a JDBC proxy tool like datasource-proxy or p6spy is the best approach to logging SQL statements. If you are writing data access code, you have to use logging. In this article, I’m going to show you how you can log the database transaction id associated with a given SQL statement using the MDC (Mapped Diagnostic Context) feature offered by many logging frameworks. So, enjoy spending your time on the things you love rather than fixing performance issues in your production system on a Saturday night! Well, Hypersistence Optimizer is that tool!Īnd it works with Spring Boot, Spring Framework, Jakarta EE, Java EE, Quarkus, or Play Framework. Follow having a tool that can automatically detect JPA and Hibernate performance issues. ![]()
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