A very little known feature in jOOQ is the Formattable.formatChart() capability, which allows for formatting any jOOQ result as an ASCII chart. This can be useful for quick plotting of results in your console application. Assuming you have a result set of this form (which is what you're getting when you call result.format() or just … Continue reading Formatting ASCII Charts With jOOQ
Category: sql
This category contains posts about SQL in general or some RDBMS’s SQL dialect
Standard SQL/JSON – The Sobering Parts
It's been almost 1 year now since jOOQ 3.14 was released in October 19, 2020 with SQL/JSON (and SQL/XML) support. Half a year later, we've released jOOQ 3.15 with MULTISET support, which builds on top of these features to offer type-safe nested collections, the way every ORDBMS should implement them. Building (dogfooding) on top of … Continue reading Standard SQL/JSON – The Sobering Parts
How to Get an RDBMS Server Version with SQL
Do you need to know what RDBMS Server version you're on, and you only have SQL at your disposal? No problem. Most RDBMS provide you with that information in some form of meta data table. Here's how: -- ClickHouse select version(); -- CockroachDB select version(); -- Db2 select service_level from table (sysproc.env_get_inst_info()) t -- Derby … Continue reading How to Get an RDBMS Server Version with SQL
Use IN List Padding to Your JDBC Application to Avoid Cursor Cache Contention Problems
A problem few developers are aware of is the possibility of running into "cursor cache contention" or "execution plan cache contention" problems when using IN lists in SQL. The problem that is described in lengths in previous articles, can be summarised as this. All of these are distinct SQL queries and need to be parsed … Continue reading Use IN List Padding to Your JDBC Application to Avoid Cursor Cache Contention Problems
Calculating Pagination Metadata Without Extra Roundtrips in SQL
When paginating results in SQL, we use standard SQL OFFSET .. FETCH or a vendor specific version of it, such as LIMIT .. OFFSET. For example: SELECT first_name, last_name FROM actor ORDER BY actor_id OFFSET 10 ROWS FETCH NEXT 10 ROWS ONLY As always, we're using the Sakila database for this example. This is rather … Continue reading Calculating Pagination Metadata Without Extra Roundtrips in SQL
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
Translating Stored Procedures Between Dialects
In the past years, we've invested a lot of effort into improving our procedural language capabilities in jOOQ. What started with a simple internal API to support the emulations of DDL clauses like these: -- Some dialect that supports this create table if not exists t (i varchar(10)); -- Db2 begin declare continue handler for … Continue reading Translating Stored Procedures Between Dialects
Implementing a generic REDUCE aggregate function with SQL
So, @rotnroll666 nerd sniped me again. Apparently, the Neo4j Cypher query language supports arbitrary reductions, just like any functional collection API, oh say, the JDK Stream API: Stream.of(2, 4, 3, 1, 6, 5) .reduce((i, j) -> i * j) .ifPresent(System.out::println); // Prints 720 SQL doesn't have this, yet it would be very useful to be … Continue reading Implementing a generic REDUCE aggregate function with SQL
Automatically Transform Oracle Style Implicit Joins to ANSI JOIN using jOOQ
While jOOQ is mostly being used as an internal SQL DSL for embedded, dynamic SQL in Java, where it offers the best solution on the market, jOOQ is increasingly also used for one of its secondary features: Its parser. Having been introduced in jOOQ 3.9 primarly for the purpose of being able to parse DDL … Continue reading Automatically Transform Oracle Style Implicit Joins to ANSI JOIN using jOOQ
Nesting Collections With jOOQ 3.14’s SQL/XML or SQL/JSON support
One of the main features of ORMs is M as in Mapping. Libraries like jOOQ help auto-mapping flat or nested database records onto Java classes that have the same structure as the SQL result set. The following has always been possible in jOOQ, assuming PostgreSQL's INFORMATION_SCHEMA (using the generated code from the jOOQ-meta module): class … Continue reading Nesting Collections With jOOQ 3.14’s SQL/XML or SQL/JSON support