infinilabs/analysis-ik

analysis-ik is a plugin that adds Chinese-language text analysis to Elasticsearch and OpenSearch, two popular search engines used to build fast, scalable search features in applications. The core problem it solves is that Chinese text has no spaces between words, making it hard for search engines to know where one word ends and another begins. This plugin integrates the IK analyzer (a Chinese text tokenizer, meaning a tool that splits text into meaningful units called tokens) so that search queries and indexed content are broken down correctly. The plugin provides two tokenizer modes. "ik_max_word" performs the finest-grained split, generating all possible word combinations from a phrase, useful when you want to match any possible way a query might overlap with the content. "ik_smart" performs a coarser, more minimal split, useful for phrase-level queries. You configure which mode to use per field in your Elasticsearch index mapping. Custom dictionaries are supported: you can add your own vocabulary files (lists of words, one per line, in UTF-8 encoding) to extend the default dictionary. The plugin also supports hot-reloading dictionaries from a remote URL, meaning you can update the word list without restarting the search engine, as long as the server serving the file returns standard HTTP caching headers. Installation is done via the Elasticsearch or OpenSearch plugin CLI with a single command. The plugin is written in Java, licensed under Apache 2.0, and maintained by INFINI Labs.