AI Semantic Expansion
This module enhances Search API search results by adding AI-generated synonyms and search intent phrases. It processes content in the background, stores the AI-generated text in a local cache, and then injects it into your search index without needing a vector database. This allows for more intelligent semantic search directly from your standard relational database.
The AI Semantic Expansion module enriches your Search API indexes with AI-generated synonyms and search intent phrases, enabling semantic search on standard relational databases (MySQL, MariaDB, PostgreSQL) — no vector database required.
When a node is saved, the module queues it for processing. A background queue worker sends the node's content to your configured LLM provider (via the Drupal AI module) and stores the generated synonym text in a local cache table. During Search API indexing, the processor injects that cached text into a virtual field (ai_semantic_synonyms), which can be mapped and boosted like any other fulltext field.
Key features
- Zero live HTTP calls during indexing. All AI generation happens in the background queue worker; the Search API processor only reads from the local cache.
- Hash-based deduplication. The cache row is only regenerated when the source content actually changes, preventing redundant API calls.
- Provider-agnostic. Works with any chat-capable provider configured in the Drupal AI module (OpenAI, Anthropic, Ollama, and others).
- Configurable per index. Source fields, character limit, system prompt, and AI provider are all set on the Search API processor configuration form.
- Bulk pre-warm command. Run
drush ai-expand:batchto pre-populate the cache for all existing nodes before the first indexing run. - Cache management. A “Flush AI cache” button on the processor form lets administrators clear and regenerate all entries. Changing the LLM prompt automatically invalidates the cache and notifies administrators to re-run the batch command.
Requirements
- Drupal 10.4 or 11
- Drupal AI module with at least one chat-capable provider configured
- Search API module with an active index
Installation
- Enable the module:
drush en ai_semantic_expansion - Run database updates:
drush updb - Go to your Search API index → Processors and enable AI Semantic Expansion.
- Go to Fields and add the AI Semantic Synonyms virtual field; set its type to Fulltext and apply a boost weight.
- Pre-warm the cache for existing content:
drush ai-expand:batch - Re-index:
drush search-api-index