Sandbox::https://redirect.github.com/quickwit-oss/quickwit/pull/6962

PSeitz · 2026-10-29T16:36:52Z

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PSeitz · 2026-10-29T16:37:06Z

Replaces #6958 to use the source branch PSeitz/quickwit:use_feuer. Both branches point to the same commit (0e0e4933f6c7605912116f9ead69c29fa163bd34), so this replacement changes the branch name, not the code.

Extract the download coalescer from quickwit-oss#6962 so split readers can batch nearby reads without Feuer. Copy proper subranges to avoid retaining larger merged allocations, and preserve cancellation and error propagation. AI-assisted extraction using openai/gpt-6-astra.

trinity-1686a

i still have to go through quickwit-search

trinity-1686a · 2026-11-02T10:21:52Z

+#   # Feuer fast-field RAM cache. Default 1G. Omitted while disk_cache
+#   # is set disables this cache; set a capacity explicitly to keep both.
 #   fast_field_cache_capacity: 1G


i wonder what we want to do about deprecated config options like that, i think we want to remove them from the sample documentation (but keep them in the configuration docs until actually removed)

my plan is to use their values for feuer

fast_field_cache_capacity + split_footer_capacity = feuer_capacity

I commented to as deprecated

trinity-1686a · 2026-11-02T11:09:21Z

+#   disk_cache:
+#     disk_capacity: 1500GiB
+#     memory_capacity: 15GiB
+#   # Alternatively, replace the scalar result-cache settings above with:


a disk cache with a memory capacity is a rare sight

renamed to storage_cache

storage_cache_directory is outside, because it is shared by the (holy) 3 caches

trinity-1686a · 2026-11-04T11:22:59Z

    /// Search split cache. `None` if no split cache is configured.
    pub split_cache_opt: Option<Arc<SearchSplitCache>>,
+    /// Process-wide cache for split byte ranges, with optional disk storage.
+    pub disk_cache_opt: Option<Arc<FeuerSplitRangeCache>>,


disk cache isn't a great name if the disk part is even optional

Called storage_cache now

trinity-1686a · 2026-11-04T15:09:51Z

            .predicate_cache
-            .get(split_id.clone(), term_absence_cache_key(term))
+            .get_async(split_id.clone(), term_absence_cache_key(term))
+            .await


should this get parallelized? (awaiting futures in a loop instead of concurrently)

it should, p95 accesstime can peak to a few seconds ... although I don't have it per requested size in the metrics. I'll update that

although we usually only have one hit here currently, so there's no real parallelism yet

trinity-1686a · 2026-11-04T15:10:01Z

+            ctx.searcher_context
+                .predicate_cache
+                .put_async(split_id.clone(), key, segment_id, HitSet::empty())
+                .await;


should this get parallelized? (awaiting futures in a loop instead of concurrently)

trinity-1686a · 2026-11-04T15:35:18Z


 /// A (half-open) range bounded inclusively below and exclusively above [start..end).
-#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Serialize)]


oh, that's interesting. I wonder if feuer should take a key that's Hash, and have a normal looking Hasher with a finish_u128() function so that it can be compatible with what people are used too. that might have limitations when used with type for which the Hash impl can easily cause collisions independantly of hashers though (i recall reading something about PathBuf)
going totally the other way, feuer could accept any Serialize + Eq, and internally use some sort of HashingSerializer so there's no need for json encoding in cache access
(these are ideas, not change requests)

hmm yes Serialize on the keys + hashing to u128 would make sense

Hash is actually less of a hassle than Serialize

trinity-1686a · 2026-11-04T15:40:10Z

+        assert!(
+            encoded_result.len() >= 32,
+            "invalid cached predicate header"
+        );


i'm a bit scared by these assertion. In the realm of a possibly persistent cache, that can mean a bad entry keeps a pod from recovering until a PV gets manually deleted, i'd prefer if we ignored the error, or cleared the faulty entry from cache (same for LeafSearchCache::get_async actually))

Yes, that's the biggest risk. In normal operation we should be safe by two mechanisms.

Every disk payload is checksummed

You can give the cache a payload version, so it will ignore the whole disk cache if a version changes. (so we don't need to version partial response cache etc.)

I changed it so it will ignore entries that can't be deserialized

(i'm not too worried about corruption, i haven't checked feuer disk yet, but i know about the checksumming, i'm more concerned about logic error inserting invalid values somehow; possibly through code that doesn't exist today but will exist tomorrow, which up to now was problematic but not that much, and with the assertion that was, would become very problematic. in general this would fit clearly in the "new failure mode" bucket, which is a bucket i'd rather keep small if not empty)

Without disk cache that's the same issue we have today, no?

yes, without disk risk is similar. I'm reviewing this PR under the assumption that disk will be a thing: we won't go over everything related to feuer integration in quickwit a 2nd time when we decide we have built enough confidence on the disk part

trinity-1686a · 2026-11-04T15:43:48Z

+        }
+    }
+
+    pub fn disk(cache: FeuerCache) -> Self {


in memory cache gets metrics, but disk doesn't?

also i'm in favour of making async functions that require a runtime handle, even if they don't actually await

in memory cache gets metrics, but disk doesn't?

I enabled it for both. Long-term we may drop them since they are covered by Feuer

also i'm in favour of making async functions that require a runtime handle, even if they don't actually await

replaced it with sync put (which I added to Feuer)

trinity-1686a · 2026-11-04T15:51:55Z

+
+    /// Bridge Tantivy's synchronous predicate API. Disk-backed calls MUST run on a CPU or
+    /// blocking thread, never a Tokio worker. The saved runtime drives Feuer's I/O tasks.
+    pub fn block_on<F: Future>(&self, future: F) -> F::Output {


i don't like this function for reasons already stated. it's not clear to me why we need to call feueur from blocking context. if we do need that, having a block_on on ResultCache feels very strange. having something like a get_many_blocking could make sense so that at least we don't do multiple rtt to storage when we could do concurrent reads

chatgpt-codex-connector · 2026-11-10T14:37:44Z

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chatgpt-codex-connector · 2026-11-10T14:45:48Z

+                    ) || error.is::<io::Error>()) =>
+            {
+                let mut memory_config = config.clone();
+                memory_config.disk_capacity = bytesize::ByteSize::b(0);


Fail startup instead of discarding the disk tier

When a production node cannot open the configured cache because of a permission, filesystem, direct-I/O, or io_uring error, this branch rewrites the disk capacity to zero and lets startup succeed. The node then runs until restart without the configured disk capacity, potentially sending a large volume of unexpected misses to object storage; a warning and gauge do not make the deployment valid. Return the initialization error instead of hiding it behind a memory-only cache, as required for production-path failures.

AGENTS.md reference: AGENTS.md:L19-L19

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chatgpt-codex-connector · 2026-11-10T14:45:49Z

+            return Ok(());
+        }
+        let _in_flight_guards = object_storage_get_slice_in_flight_guards(buffer.len());
+        default_get_slice_into(self, path, range, buffer).await?;


Retry Azure reads through the full response body

When an Azure download fails after its first chunk, this path calls default_get_slice_into, which consumes the reader after get_slice_stream's retry(...) closure has already returned (that closure only peeks the first chunk). Before this change, get_slice kept download_all inside the retry closure; with the default storage cache, every cache miss now uses this method, so a retryable later page/body error fails the split immediately. Keep the full body read under the Azure retry policy.

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chatgpt-codex-connector · 2026-11-10T14:45:49Z

            // TODO remove the clone here.
-            .get(split.clone(), search_request.clone())
+            .get_async(split.clone(), search_request.clone())
+            .await


Run per-split disk cache lookups concurrently

When partial_request_cache has a disk tier and a leaf request contains many splits, each lookup here can perform a disk read, but the surrounding loop does not start the next lookup until this .await completes. This puts the sum of all disk-hit latencies on the request's critical path before any search tasks are scheduled, which is especially costly for requests assigned hundreds or thousands of splits. Drive these lookups concurrently with a sensible bound, then merge the results.

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i agree with codex

trinity-1686a · 2026-11-12T11:05:39Z

+
+// The native schema, typed registrations, inventory entries, and exporter buckets all come
+// from this list. Keep descriptions and ordered labels identical to the pinned Feuer revision.
+macro_rules! declare_metrics {


should this be in quickwit-common?

hmm I would leave it here for now

trinity-1686a · 2026-11-12T14:53:53Z

            // TODO remove the clone here.
-            .get(split.clone(), search_request.clone())
+            .get_async(split.clone(), search_request.clone())
+            .await


i agree with codex

trinity-1686a · 2026-11-12T14:57:27Z

-
-impl CacheKeyHasher {
-    fn random() -> Self {
-        // Seed SipHash from a cryptographically secure thread-local RNG initialized from OS


this makes me wonder if we don't want a "better" hash in feuer so a user can't poison the cache by making its query collide with someonelse's. in the grand scheme of scheme, how expensive are cache lookups in feuer?
maps in aggregation:

concern is hashdos (so pathological performance)

there can be up to a few million lookup per split/segment
feuer:

concern is poisoning/transient state corruption (so correctness for other callers)

usually a few dozen queries per split, maybe a few hundred for some automatons

Benchmarked on Graviton4 Linux, comparing XXH3-128 with fixed-seed SipHash-1-3-128. Median nanoseconds per operation across five samples.

Key Key size XXH3 hash (ns) Sip13 hash (ns) XXH3 memory hit (ns) Sip13 memory hit (ns)

Split slice 82 B 39 42 185 190

Predicate, one term 75 B 34 32 185 183

Predicate, 16 terms 948 B 88 254 242 406

Predicate, 64 terms 3.6 KB 253 937 426 1,090

Predicate, 256 terms 14.4 KB 864 3,668 1,026 3,822

Predicate, large string 65.6 KB 3,840 16,599 4,039 16,689

Partial request, one term 220 B 188 98 339 246

Partial request, 64 terms 3.8 KB 397 989 581 1,132

Partial request, 64 terms + aggregation 3.9 KB 415 1,021 579 1,163

I think these numbers should be fine to switch to SipHash. I bumped the format version to store the seed.

trinity-1686a · 2026-11-12T15:15:10Z

+    // Keep the same key and payload across retries. Returning an error to Feuer
+    // would stop delivery and silently discard subsequent events.
+    let payload = package.to_vec();
+    loop {


if upload never succeed (RO bucket access...), this block the with_trace closure from returning, which i think end up translating to a channel filling up, after ~260k events this makes all cache access blocking

trinity-1686a · 2026-11-12T15:16:56Z

+    /// Cache an immutable object without disk reads or waiting for disk admission.
+    /// Values for a key must be equivalent. An existing memory entry is retained.
+    /// Disk writes use Feuer's best-effort background queue.
+    pub fn put(&self, key: &(impl Hash + ?Sized), bytes: OwnedBytes) {


we might not want to insert OwnedBytes that are "too big" (definitely not larger than the cache capacity, we used to reject that, possibly not larger than some fraction of it, to not evict everything at once)

trinity-1686a · 2026-11-12T15:36:53Z

            // rewrite is needed here.
            let mut split_search_guard = SplitSearchStateGuard::new(split_outcome_counters.clone());
            split_search_guard.set_state(SplitSearchState::CacheHit);
            incremental_merge_collector.add_result(cached_response)?;


agentic review is concerned that this can fail, and repeatedly fail, if for some reason the partial response doesn't decode right. it was already a problem before and we never suffered from it, it becomes somewhat worse with a disk cache, but it's not that concerning imo, given we never saw that problem before, and the values are already partially decoded when we reach here

Use a 10 MB threshold for disk fallthrough. Remove the redundant disk-capacity precheck as requested.

PSeitz added area:storage S3, GCS, Azure and local storage type:enhancement An improvement to something that exists, or its deprecation or removal area:search Root and leaf search, caches, sorting, pagination, Lambda offload labels Oct 29, 2026

This was referenced Oct 29, 2026

Use Feuer Disk-Cache #6958

Closed

Fix OOM - Streaming Coalescing in Quickwit #6985

Draft

trinity-1686a reviewed Nov 4, 2026

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PSeitz marked this pull request as ready for review November 10, 2026 14:37

PSeitz requested a review from a team as a code owner November 10, 2026 14:37

datadog-official Bot added the type:feature A new capability, such as an endpoint, query type, source, setting or command label Nov 10, 2026

chatgpt-codex-connector Bot reviewed Nov 10, 2026

View reviewed changes

Use Feuer for searcher caches

b067024

PSeitz force-pushed the use_feuer branch from 41d35f3 to b067024 Compare November 10, 2026 20:18

Weight predicate cache retention by fill CPU time

b73a35e

PSeitz force-pushed the use_feuer branch from 11a412d to b73a35e Compare November 12, 2026 10:13

trinity-1686a reviewed Nov 12, 2026

View reviewed changes

PSeitz added 2 commits November 12, 2026 18:46

Clarify storage cache comments

92c2097

Fetch large ranges from storage when the disk queue is busy

26c4deb

Use a 10 MB threshold for disk fallthrough. Remove the redundant disk-capacity precheck as requested.

Key	Key size	XXH3 hash (ns)	Sip13 hash (ns)	XXH3 memory hit (ns)	Sip13 memory hit (ns)
Split slice	82 B	39	42	185	190
Predicate, one term	75 B	34	32	185	183
Predicate, 16 terms	948 B	88	254	242	406
Predicate, 64 terms	3.6 KB	253	937	426	1,090
Predicate, 256 terms	14.4 KB	864	3,668	1,026	3,822
Predicate, large string	65.6 KB	3,840	16,599	4,039	16,689
Partial request, one term	220 B	188	98	339	246
Partial request, 64 terms	3.8 KB	397	989	581	1,132
Partial request, 64 terms + aggregation	3.9 KB	415	1,021	579	1,163

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PSeitz commented Oct 29, 2026

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