Index on Micha Kops' Tech Notes

Lucene by Example: Specifying Analyzers on a per-field-basis and writing a custom Analyzer/Tokenizer

Sun, 06 Jul 2014 00:00:00 +0200

Lucene is my favourite search engine library and the more often I use it in my projects the more features or functionality I find that were unknown to me.

Two of those features I’d like to share in the following tutorial is one the one hand the possibility to specify different analyzers on a per-field basis and on the other hand the API to create a simple character based tokenizer and analyzer within a few steps.

JPA Persistence and Lucene Indexing combined in Hibernate Search

Sun, 05 Feb 2012 00:00:00 +0100

Often we’re writing an application that has to handle entities that – on the one side need to be persisted in a relational database using standards like the Java Persistence API (JPA) and using frameworks like Hibernate ORM or EclipseLink.

On the other side those entities and their fields are often stored in a highspeed indexer like Lucene. From this situation arises a bunch of common problems .. to synchronize both data sources, to handle special data mapped in an entity like an office document and so on..

How to build a quick Lucene Search

Thu, 25 Mar 2010 00:00:00 +0100

Helo – today I wanted to post a small tutorial for a small index and search operation using the Lucene indexer and Maven for the project setup.

Setup

Create an empty Maven sample project using the Eclipse Maven Plugin or use the following console command:
```
mvn archetype:create -DgroupId=com.hascode.demo.search -DartifactId=lucene-sample
```

Here is my pom.xml there are some dependencies for Lucene defined:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.hascode.demo.search</groupId>
  <artifactId>lucene-sample</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <name>My Lucene Search Sample</name>
  <description>Lucene Search Sample</description>
  <dependencies>
    <dependency>
      <groupId>org.apache.lucene</groupId>
      <artifactId>lucene-core</artifactId>
      <version>2.4.1</version>
    </dependency>
    <dependency>
      <groupId>lucene</groupId>
      <artifactId>lucene</artifactId>
      <version>1.4.3</version>
    </dependency>
  </dependencies>
</project>

Postgres Snippets

Mon, 01 Mar 2010 00:00:00 +0100

Administration & Configuration

Connections

Show Max Connections (value and source)

SELECT setting, source, sourcefile, sourceline
FROM pg_settings
WHERE name = 'max_connections';

Set Max Connections

ALTER system SET max_connections = 250;

Kill Connections for a Database

SELECT pg_terminate_backend(pid)
FROM pg_catalog.pg_stat_activity
-- we don't want to kill our own connection
WHERE pid != pg_backend_pid()
-- we don't want to kill connections to other databases
AND datname = 'MYDATABASE'

Show Statement Timeout Settings for All Users

SELECT r.rolname,
       (SELECT unnest(s.setconfig) FROM pg_db_role_setting s WHERE s.setrole = r.oid AND s.setconfig::text LIKE '%statement_timeout%' LIMIT 1) AS statement_timeout
FROM pg_roles r
WHERE r.rolcanlogin
ORDER BY r.rolname;