The Many Different Ways to Fetch Data in jOOQ

The jOOQ API is all about convenience, and as such, an important operation (the most important one?) like fetch() must come with convenience, too. The default way to fetch data is this: Result<Record1<String>> result = ctx.select(BOOK.TITLE) .from(BOOK) .fetch(); for (Record1<String> record : result) { // ... } It fetches the entire result set into memory … Continue reading The Many Different Ways to Fetch Data in jOOQ

Setting the JDBC Statement.setFetchSize() to 1 for Single Row Queries

An interesting hint by Vladimir Sitnikov has made me think about a new benchmark for jOOQ: https://twitter.com/lukaseder/status/1407662449331949568 The benchmark should check whether single row queries should have a JDBC Statement.setFetchSize(1) call made to them by default. The Javadoc of the method says: Gives the JDBC driver a hint as to the number of rows that … Continue reading Setting the JDBC Statement.setFetchSize() to 1 for Single Row Queries

Nested Transactions in jOOQ

Since jOOQ 3.4, we have an API that simplifies transactional logic on top of JDBC in jOOQ, and starting from jOOQ 3.17 and #13502, an equivalent API will also be made available on top of R2DBC, for reactive applications. As with everything jOOQ, transactions are implemented using explicit, API based logic. The implicit logic implemented … Continue reading Nested Transactions in jOOQ

Using jOOQ’s DiagnosticsConnection to detect N+1 Queries

N+1 queries are a popular problem in many applications that run SQL queries. The problem can be described easily as follows: 1 query fetching a parent value is runN queries fetching each individual child values are run This problem isn't limited to SQL, it can happen with any poorly designed API that does not allow … Continue reading Using jOOQ’s DiagnosticsConnection to detect N+1 Queries

Ad-hoc Data Type Conversion with jOOQ 3.15

jOOQ 3.15 shipped with a ton of new features, the most important ones being: MULTISET support (type safe, nested collections)Reactive SQL support via R2DBC A very useful, lesser known new feature is "ad-hoc data type conversion". Data type converters and bindings have been around in jOOQ for a long time. Their goal is to allow … Continue reading Ad-hoc Data Type Conversion with jOOQ 3.15

Simulating Latency with SQL / JDBC

I've run across a fun little trick to simulate latency in your development environments when testing some SQL queries. Possible use-cases including to validate that backend latency won't bring down your frontend, or that your UX is still bearable, etc. https://twitter.com/gunnarmorling/status/1361061234569805832 The solution is PostgreSQL and Hibernate specific, though to doesn't have to be. Besides, … Continue reading Simulating Latency with SQL / JDBC

How to Run a Bulk INSERT .. RETURNING Statement With Oracle and JDBC

When inserting records into SQL databases, we often want to fetch back generated IDs and possibly other trigger, sequence, or default generated values. Let's assume we have the following table: -- DB2 CREATE TABLE x ( i INT GENERATED ALWAYS AS IDENTITY PRIMARY KEY, j VARCHAR(50), k DATE DEFAULT CURRENT_DATE ); -- PostgreSQL CREATE TABLE … Continue reading How to Run a Bulk INSERT .. RETURNING Statement With Oracle and JDBC

How to Fetch Oracle DBMS_OUTPUT from JDBC

When working with Oracle stored procedures, it is not uncommon to have debug log information available from DBMS_OUTPUT commands. For instance, if we have a procedure like this: CREATE TABLE my_table (i INT); CREATE OR REPLACE PROCEDURE my_procedure (i1 INT, i2 INT) IS BEGIN INSERT INTO my_table SELECT i1 FROM dual UNION ALL SELECT i2 … Continue reading How to Fetch Oracle DBMS_OUTPUT from JDBC

How I Incorrectly Fetched JDBC ResultSets. Again.

You know JDBC, right? It's that really easy, concise API that we love to use to work with virtually any database, relational or not. It has essentially three types that you need to care about: Connection Statement (and its subtypes) ResultSet All the other types some sort of utilities. Now, with the above three, we … Continue reading How I Incorrectly Fetched JDBC ResultSets. Again.

jOOQ Tuesdays: Brett Wooldridge Shows What it Takes to Write the Fastest Java Connection Pool

Welcome to the jOOQ Tuesdays series. In this series, we’ll publish an article on the third Tuesday every other month where we interview someone we find exciting in our industry from a jOOQ perspective. This includes people who work with SQL, Java, Open Source, and a variety of other related topics. I'm very excited to … Continue reading jOOQ Tuesdays: Brett Wooldridge Shows What it Takes to Write the Fastest Java Connection Pool