perf[fsst]: like pushdown using a dfa (#6935)

Fsst `like` execution without decompression.

This uses a DFA over the symbol table and the like expression.

Once this is proved out we could think about putting this in fsst-rs?

---------

Signed-off-by: Joe Isaacs <joe.isaacs@live.co.uk>

Author: joseph-isaacs

.github/workflows/fuzz.yml

@@ -99,6 +99,42 @@ jobs:
       gh_token: ${{ secrets.GITHUB_TOKEN }}
       incident_io_alert_token: ${{ secrets.INCIDENT_IO_ALERT_TOKEN }}
 
+  # ============================================================================
+  # FSST LIKE Fuzzer
+  # ============================================================================
+  fsst_like_fuzz:
+    name: "FSST LIKE Fuzz"
+    uses: ./.github/workflows/run-fuzzer.yml
+    with:
+      fuzz_target: fsst_like
+      jobs: 16
+    secrets:
+      R2_FUZZ_ACCESS_KEY_ID: ${{ secrets.R2_FUZZ_ACCESS_KEY_ID }}
+      R2_FUZZ_SECRET_ACCESS_KEY: ${{ secrets.R2_FUZZ_SECRET_ACCESS_KEY }}
+
+  report-fsst-like-fuzz-failures:
+    name: "Report FSST LIKE Fuzz Failures"
+    needs: fsst_like_fuzz
+    if: always() && needs.fsst_like_fuzz.outputs.crashes_found == 'true'
+    permissions:
+      issues: write
+      contents: read
+      id-token: write
+      pull-requests: read
+    uses: ./.github/workflows/report-fuzz-crash.yml
+    with:
+      fuzz_target: fsst_like
+      crash_file: ${{ needs.fsst_like_fuzz.outputs.first_crash_name }}
+      artifact_url: ${{ needs.fsst_like_fuzz.outputs.artifact_url }}
+      artifact_name: fsst_like-crash-artifacts
+      logs_artifact_name: fsst_like-logs
+      branch: ${{ github.ref_name }}
+      commit: ${{ github.sha }}
+    secrets:
+      claude_code_oauth_token: ${{ secrets.CLAUDE_CODE_OAUTH_TOKEN }}
+      gh_token: ${{ secrets.GITHUB_TOKEN }}
+      incident_io_alert_token: ${{ secrets.INCIDENT_IO_ALERT_TOKEN }}
+
   # ============================================================================
   # Compress Roundtrip Fuzzer
   # ============================================================================

Cargo.lock

@@ -2,13 +2,13 @@
 extend-ignore-identifiers-re = ["ffor", "FFOR", "FoR", "typ", "ratatui"]
 # We support a few common special comments to tell the checker to ignore sections of code
 extend-ignore-re = [
-    "(#|//)\\s*spellchecker:ignore-next-line\\n.*",                      # Ignore the next line
-    "(?Rm)^.*(#|//)\\s*spellchecker:disable-line$",                      # Ignore line that ends with this hint
+    "(#|//)\\s*spellchecker:ignore-next-line\\n.*", # Ignore the next line
+    "(?Rm)^.*(#|//)\\s*spellchecker:disable-line$", # Ignore line that ends with this hint
     "(?s)(#|//)\\s*spellchecker:off.*?\\n\\s*(#|//)\\s*spellchecker:on", # Ignore block between hints
 ]
 
 [files]
-extend-exclude = ["/vortex-bench/**", "/docs/references.bib", "benchmarks/**", "vortex-sqllogictest/slt/**"]
+extend-exclude = ["/vortex-bench/**", "/docs/references.bib", "benchmarks/**", "vortex-sqllogictest/slt/**", "encodings/fsst/src/dfa/tests.rs", "encodings/fsst/src/dfa/flat_contains.rs"]
 
 [type.py]
 extend-ignore-identifiers-re = [

_typos.toml

@@ -41,7 +41,7 @@ harness = false
 required-features = ["_test-harness"]
 
 [[bench]]
-name = "fsst_contains"
+name = "fsst_like"
 harness = false
 required-features = ["_test-harness"]
 

encodings/fsst/Cargo.toml

@@ -2,3 +2,23 @@
 
 A Vortex Encoding for Binary and Utf8 data that utilizes the [Fast Static Symbol Table](https://github.com/spiraldb/fsst)
 compression algorithm.
+
+## LIKE Pushdown
+
+The FSST encoding has a specialized LIKE fast path for a narrow subset of
+patterns:
+
+- `prefix%`
+- `%needle%`
+
+Unsupported shapes, including `_`, `%suffix`, or patterns with interior
+wildcards, fall back to ordinary decompression-based LIKE evaluation.
+
+There are also two implementation limits on the pushdown path, both measured in
+pattern bytes:
+
+- `prefix%` supports up to 253 bytes.
+- `%needle%` supports up to 254 bytes.
+
+Patterns beyond those limits are still evaluated correctly, but they do so via
+the fallback path instead of the DFA matcher.

encodings/fsst/README.md

@@ -80,7 +80,19 @@ impl Dataset {
         }
     }
 
-    fn pattern(&self) -> &'static str {
+    fn prefix_pattern(&self) -> &'static str {
+        match self {
+            Self::Urls => "https%",
+            Self::Cb => "https://www.%",
+            Self::Log => "192.168%",
+            Self::Json => r#"{"id%"#,
+            Self::Path => "/home%",
+            Self::Email => "john%",
+            Self::Rare => "xyz%",
+        }
+    }
+
+    fn contains_pattern(&self) -> &'static str {
         match self {
             Self::Urls => "%google%",
             Self::Cb => "%yandex%",
@@ -93,15 +105,10 @@ impl Dataset {
     }
 }
 
-#[divan::bench(args = [
-    Dataset::Urls, Dataset::Cb, Dataset::Log, Dataset::Json,
-    Dataset::Path, Dataset::Email, Dataset::Rare,
-])]
-fn fsst_like(bencher: Bencher, dataset: &Dataset) {
-    let fsst = dataset.fsst_array();
+fn bench_like(bencher: Bencher, fsst: &FSSTArray, pattern: &str) {
     let len = fsst.len();
     let arr = fsst.clone().into_array();
-    let pattern = ConstantArray::new(dataset.pattern(), len).into_array();
+    let pattern = ConstantArray::new(pattern, len).into_array();
     bencher.bench_local(|| {
         Like.try_new_array(len, LikeOptions::default(), [arr.clone(), pattern.clone()])
             .unwrap()
@@ -110,3 +117,19 @@ fn fsst_like(bencher: Bencher, dataset: &Dataset) {
             .unwrap()
     });
 }
+
+#[divan::bench(args = [
+    Dataset::Urls, Dataset::Cb, Dataset::Log, Dataset::Json,
+    Dataset::Path, Dataset::Email, Dataset::Rare,
+])]
+fn fsst_prefix(bencher: Bencher, dataset: &Dataset) {
+    bench_like(bencher, dataset.fsst_array(), dataset.prefix_pattern());
+}
+
+#[divan::bench(args = [
+    Dataset::Urls, Dataset::Cb, Dataset::Log, Dataset::Json,
+    Dataset::Path, Dataset::Email, Dataset::Rare,
+])]
+fn fsst_contains(bencher: Bencher, dataset: &Dataset) {
+    bench_like(bencher, dataset.fsst_array(), dataset.contains_pattern());
+}

encodings/fsst/benches/fsst_contains.rs encodings/fsst/benches/fsst_like.rsencodings/fsst/benches/fsst_contains.rs renamed to encodings/fsst/benches/fsst_like.rs

@@ -30,6 +30,10 @@ impl vortex_array::scalar_fn::fns::cast::kernel::CastReduce for vortex_fsst::FSS
 
 pub fn vortex_fsst::FSST::cast(array: &vortex_fsst::FSSTArray, dtype: &vortex_array::dtype::DType) -> vortex_error::VortexResult<core::option::Option<vortex_array::array::ArrayRef>>
 
+impl vortex_array::scalar_fn::fns::like::kernel::LikeKernel for vortex_fsst::FSST
+
+pub fn vortex_fsst::FSST::like(array: &vortex_fsst::FSSTArray, pattern: &vortex_array::array::ArrayRef, options: vortex_array::scalar_fn::fns::like::LikeOptions, _ctx: &mut vortex_array::executor::ExecutionCtx) -> vortex_error::VortexResult<core::option::Option<vortex_array::array::ArrayRef>>
+
 impl vortex_array::vtable::VTable for vortex_fsst::FSST
 
 pub type vortex_fsst::FSST::Array = vortex_fsst::FSSTArray