TL;DR

Elasticsearch now supports native health checks, improving observability and allowing easier integration with container orchestration tools (like Kubernetes).

Fixes Worth Knowing

Resolved an issue causing incorrect results when using the terms aggregation (data analysis feature) with large numbers of terms. Fixed a bug where cluster allocation (resource management) could stall under high load.

Before You Upgrade

Restart all Elasticsearch nodes after upgrading to ensure the new health check endpoints are available.

TL;DR

Elasticsearch 8.19.16 includes a security fix addressing a potential denial-of-service vulnerability (DoS - attempts to make a machine unavailable).

Fixes Worth Knowing

• Fixed a potential denial-of-service vulnerability related to slow HTTP requests.
• Resolved an issue where ingest pipelines could fail with a NullPointerException (programming error) under specific conditions.

TL;DR

Elasticsearch now supports wildcard characters in index names when using the Delete By Query API, improving flexibility for data management.

Fixes Worth Knowing

• Delete By Query API now correctly handles index names containing wildcard characters (special characters representing other values).
• Fixed a potential race condition when reindexing data, preventing rare data loss scenarios.

TL;DR

Elasticsearch 9.0 introduces significant changes to time-based data handling with Data Streams, offering simplified data tiering and retention.

Breaking

• Java 17 is now required. (Programming language)
• The _source field is no longer returned by default. (Data storage format) - Explicitly request it in queries.

New

• Data Streams now support automatic rollover and lifecycle management. (Automated data handling)
• Improved performance for time series data. (Data analysis)

Fixes Worth Knowing

• Fixed a bug causing incorrect results when using range queries on date fields. (Query functionality)

TL;DR

Elasticsearch 8.0 introduces significant changes to time-based data handling with data streams, replacing the old index lifecycle management approach and offering simplified data management.

Breaking

• Index lifecycle policies are removed (automatic index management).
• The _template API is removed (use composable templates).

New

• Data Streams (simplified data ingestion) provide a unified way to write and manage time-based data.
• Composable Templates (index configuration) allow for more flexible and reusable index settings.

Fixes Worth Knowing

• Fixed a bug causing incorrect results when using range queries with date histograms.
• Improved performance of wildcard queries against large text fields.

TL;DR

Elasticsearch 6.8.23 improves security by updating the bundled JDK to address several critical vulnerabilities.

Fixes Worth Knowing

• Resolved a potential issue where high CPU usage could occur during index operations (indexing is adding data).
• Fixed a bug causing incorrect results when using the terms aggregation with large numbers of terms (aggregations summarize data).