From ec7da6f6f68b010f1c14ad0e2ea61b557158e61e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Istv=C3=A1n=20Zolt=C3=A1n=20Szab=C3=B3?= Date: Thu, 7 Aug 2025 17:12:27 +0200 Subject: [PATCH 1/5] Expands bbq_hnsw known issue. --- docs/release-notes/known-issues.md | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/docs/release-notes/known-issues.md b/docs/release-notes/known-issues.md index aae019b43d820..2d1fbd4540350 100644 --- a/docs/release-notes/known-issues.md +++ b/docs/release-notes/known-issues.md @@ -5,13 +5,19 @@ mapped_pages: --- # Elasticsearch known issues [elasticsearch-known-issues] + Known issues are significant defects or limitations that may impact your implementation. These issues are actively being worked on and will be addressed in a future release. Review the Elasticsearch known issues to help you make informed decisions, such as upgrading to a new version. ## 9.1.0 [elasticsearch-9.1.0-known-issues] -* An error in the configuration of vector indices with type `bbq_hnsw` may lead to significant search performance degradation on 9.1.0. To mitigate this, set the `-Dvector.rescoring.directio=false` JVM option on all search nodes, then restart the nodes. - This option can be removed in 9.1.1. + +* If `-Dvector.rescoring.directio` set to `true` per this [recommendation](https://www.elastic.co/docs/deploy-manage/production-guidance/optimize-performance/approximate-knn-search#use-direct-io-when-the-vector-data-does-not-fit-in-ram) in the configuration of vector indices with type `bbq_hnsw`, then it may lead to significant search performance degradation on 9.1.0. In some cases, kNN search latency can increase by as much as 10x. To mitigate this, set the `-Dvector.rescoring.directio=false` JVM option on all search nodes, then restart the nodes. This option can be removed in 9.1.1. + +**How do I know if my index vector type is `bbq_hnsw`?** + +* Prior to 9.1, the vector type must be explicitely set to `bbq_hnsw`. Starting with 9.1, however, `bbq_hnsw` is the default vector type for all new indices unless another type is specified. ## 9.0.3 [elasticsearch-9.0.3-known-issues] + * A bug in the merge scheduler in Elasticsearch 9.0.3 may prevent shards from closing when there isn’t enough disk space to complete a merge. As a result, operations such as closing or relocating an index may hang until sufficient disk space becomes available. To mitigate this issue, the disk space checker is disabled by default in 9.0.3 by setting `indices.merge.disk.check_interval` to `0` seconds. Manually enabling this setting is not recommended. From 0217438bff9163d094770f0f37af9c03791b9cfc Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Istv=C3=A1n=20Zolt=C3=A1n=20Szab=C3=B3?= Date: Thu, 7 Aug 2025 17:18:41 +0200 Subject: [PATCH 2/5] Refines text. --- docs/release-notes/known-issues.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/docs/release-notes/known-issues.md b/docs/release-notes/known-issues.md index 2d1fbd4540350..23acf0d02a252 100644 --- a/docs/release-notes/known-issues.md +++ b/docs/release-notes/known-issues.md @@ -10,11 +10,11 @@ Known issues are significant defects or limitations that may impact your impleme ## 9.1.0 [elasticsearch-9.1.0-known-issues] -* If `-Dvector.rescoring.directio` set to `true` per this [recommendation](https://www.elastic.co/docs/deploy-manage/production-guidance/optimize-performance/approximate-knn-search#use-direct-io-when-the-vector-data-does-not-fit-in-ram) in the configuration of vector indices with type `bbq_hnsw`, then it may lead to significant search performance degradation on 9.1.0. In some cases, kNN search latency can increase by as much as 10x. To mitigate this, set the `-Dvector.rescoring.directio=false` JVM option on all search nodes, then restart the nodes. This option can be removed in 9.1.1. +* If the `-Dvector.rescoring.directio` JVM option is set to `true` – as recommended [in this guide](https://www.elastic.co/docs/deploy-manage/production-guidance/optimize-performance/approximate-knn-search#use-direct-io-when-the-vector-data-does-not-fit-in-ram) – and used with `bbq_hnsw` type vector indices, it may cause significant search performance degradation in 9.1.0. In some cases, kNN search latency can increase by as much as 10x. To mitigate this, set the JVM option `-Dvector.rescoring.directio=false` on all search nodes and restart them. This option can be removed in 9.1.1. **How do I know if my index vector type is `bbq_hnsw`?** -* Prior to 9.1, the vector type must be explicitely set to `bbq_hnsw`. Starting with 9.1, however, `bbq_hnsw` is the default vector type for all new indices unless another type is specified. +* Prior to 9.1, the vector type had to be explicitely set to `bbq_hnsw`. Starting with 9.1, `bbq_hnsw` is the default vector type for all new indices, unless another type is specified. ## 9.0.3 [elasticsearch-9.0.3-known-issues] From e5476c1f99afcc06b6714dd5e2319e7822812fbb Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Istv=C3=A1n=20Zolt=C3=A1n=20Szab=C3=B3?= Date: Thu, 7 Aug 2025 17:33:02 +0200 Subject: [PATCH 3/5] Addresses feedback. --- docs/release-notes/known-issues.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/docs/release-notes/known-issues.md b/docs/release-notes/known-issues.md index 23acf0d02a252..de7128606614e 100644 --- a/docs/release-notes/known-issues.md +++ b/docs/release-notes/known-issues.md @@ -10,7 +10,7 @@ Known issues are significant defects or limitations that may impact your impleme ## 9.1.0 [elasticsearch-9.1.0-known-issues] -* If the `-Dvector.rescoring.directio` JVM option is set to `true` – as recommended [in this guide](https://www.elastic.co/docs/deploy-manage/production-guidance/optimize-performance/approximate-knn-search#use-direct-io-when-the-vector-data-does-not-fit-in-ram) – and used with `bbq_hnsw` type vector indices, it may cause significant search performance degradation in 9.1.0. In some cases, kNN search latency can increase by as much as 10x. To mitigate this, set the JVM option `-Dvector.rescoring.directio=false` on all search nodes and restart them. This option can be removed in 9.1.1. +* The `-Dvector.rescoring.directio` JVM option is enabled (set to `true`) by default. When used with `bbq_hnsw` type vector indices, this can cause significant search performance degradation; particularly when enough memory is available to hold all vector data. In some cases, kNN search latency can increase by as much as 10x. To mitigate this, set the JVM option `-Dvector.rescoring.directio=false` on all search nodes and restart them. This option can be removed in 9.1.1. **How do I know if my index vector type is `bbq_hnsw`?** From 734a0804faf3f364ba1737ecea786d8511bb95bb Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Istv=C3=A1n=20Zolt=C3=A1n=20Szab=C3=B3?= Date: Mon, 11 Aug 2025 09:45:18 +0200 Subject: [PATCH 4/5] Update docs/release-notes/known-issues.md --- docs/release-notes/known-issues.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/docs/release-notes/known-issues.md b/docs/release-notes/known-issues.md index de7128606614e..3566541376f56 100644 --- a/docs/release-notes/known-issues.md +++ b/docs/release-notes/known-issues.md @@ -14,7 +14,7 @@ Known issues are significant defects or limitations that may impact your impleme **How do I know if my index vector type is `bbq_hnsw`?** -* Prior to 9.1, the vector type had to be explicitely set to `bbq_hnsw`. Starting with 9.1, `bbq_hnsw` is the default vector type for all new indices, unless another type is specified. +* Prior to 9.1, the vector type had to be explicitly set to `bbq_hnsw`. Starting with 9.1, `bbq_hnsw` is the default vector type for all new indices, unless another type is specified. ## 9.0.3 [elasticsearch-9.0.3-known-issues] From 34ffa3cde1e65f6e6d686b28604dbaa1c0fc879b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Istv=C3=A1n=20Zolt=C3=A1n=20Szab=C3=B3?= Date: Mon, 11 Aug 2025 10:43:09 +0200 Subject: [PATCH 5/5] Addresses feedback. --- docs/release-notes/known-issues.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/docs/release-notes/known-issues.md b/docs/release-notes/known-issues.md index de7128606614e..f92bce4a2fa6a 100644 --- a/docs/release-notes/known-issues.md +++ b/docs/release-notes/known-issues.md @@ -14,7 +14,7 @@ Known issues are significant defects or limitations that may impact your impleme **How do I know if my index vector type is `bbq_hnsw`?** -* Prior to 9.1, the vector type had to be explicitely set to `bbq_hnsw`. Starting with 9.1, `bbq_hnsw` is the default vector type for all new indices, unless another type is specified. +* Prior to 9.1, the vector type had to be explicitly set to `bbq_hnsw`. Starting with 9.1, `bbq_hnsw` is the default vector type for dense vectors with more than 384 dimensions in new indices, unless another type is specified. ## 9.0.3 [elasticsearch-9.0.3-known-issues]