| name | Elasticsearch |
| description | Use when searching, indexing, bulk-loading, or rebuilding indices on RI's Elasticsearch cluster (locked at 5.2) via ServiceLib.Elasticsearch. |
Elasticsearch (5.2, fixed)
The cluster runs Elasticsearch 5.2 and will not change. Use ES 5.2 API shapes: _type still exists in bulk metadata, hits.total is a plain int, and modern client libraries won't work. We do not use NEST — ServiceLib.Elasticsearch is a plain HttpClient wrapper over the REST API.
Working code in this folder: Elasticsearch.cs (the ServiceLib wrapper) and ElasticsearchService.cs (JordanPrice's use of it, including the full alias rebuild). Method-level detail: reference-wrapper.md.
Conventions
- Search results are parsed as
dynamic (Newtonsoft) and navigated by property name: result.hits.hits[0]._source, null-safe with ?. and ?.ToString() ?? "". No typed models.
- Complex queries are raw string literals (
$$"""...""") with interpolated values.
- Wrapper methods return the string
"Error" on failure rather than throwing — callers must check for it.
- Indices are created without explicit mappings — let ES auto-detect field types (matches production).
- Scroll downloads (
DownloadIndex): 5000-doc batches, 1m timeout, and the scroll context is always cleared in a finally block — leaked scroll contexts hold resources on this old cluster.
Index rebuild: timestamped index + alias (JordanPrice-proven)
Zero-downtime full rebuild, proven in JordanPrice:
- Create timestamped index, e.g.
price_discount_20250116_123456
- Bulk-load all documents into it
- Atomically switch alias
price_discount in one _aliases call (remove price_discount_* + add new index)
- On failure, delete the new index; rollback is just switching the alias back
Architectural direction: the legacy Java codebase writes whole timestamped indices and flips aliases as above. RI's stated direction for new work is in-place overwrites and deletes instead of full rebuilds — prefer that for new services, but the alias pattern remains the proven fallback for full reloads.
De-aliasing for document operations
ES 5.2 misroutes single-document operations addressed to an alias. The wrapper's DeAliasURL/ConcreteIndex resolve an alias to its concrete index first and build URLs as /{concrete_index}/{alias}/{id}. Any direct document PUT/DELETE against a name that might be an alias must go through this (see reference-wrapper.md).
Bulk format nulls (BulkToJson)
BulkToJson builds the NDJSON body with an asymmetry that matters: action metadata lines are serialized keeping nulls, document lines ignoring nulls. Keep that split when touching bulk code — dropping nulls from metadata or including them in documents both cause subtle diffs against the legacy Java output.
