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compare_ore_block_256_term(s), behind every ordered ORE operator and the ORE operator class, took time that depended on where its operands first differ. A party able to time queries, without reading the stored ciphertexts, could learn how long a prefix their query value shares with stored values: the information the constant-time comparator in ore.rs keeps from them. - Within a term, every block after the first difference ran extra statements, and the `OR` short-circuit skipped a comparison on each of them. On PostgreSQL 17 (aarch64) the two nearly cancel (t = +4.9 and +13.9 through the operator path); with the short-circuit removed the extra statements alone gave t = +388, about 0.7 µs per comparison. - Across terms (text, up to six), the comparison stopped at the first unequal term: about 11 µs when the first term differs, 47 µs when only the sixth does (t below -1500). The term comparator now runs the same statements for every block: both comparisons always evaluated (integer `|`), one statement per block collecting a bitmask of differing blocks, the first difference read off its lowest set bit with arithmetic, and exactly one encrypt() and one get_bit() on every path. The array comparator keeps a fast path for single-term values and, for multi-term values, scans every paired term, latches the first unequal term and block without branching, and hashes once; its multi-term variables live in an inner block so the single-term path does not initialise them. Term counts and NULL elements are public structure and still branch. Measured with tests/timing/ore_block_256 (next commit): single-term t = +1.8 and +1.1 at about 3-8% more time; six-term t = +4.5 and +2.7 at about 31 µs either way. Results are unchanged: all 1,500 harness checks (1-6 terms, every shared-prefix length) match plaintext order and are antisymmetric, and the structural edge cases (NULL elements, equal prefixes of different lengths, empty and NULL arrays) match the previous implementation exactly. Behaviour change: multi-term values length-check every paired term, so a malformed term after the first unequal one now raises instead of being skipped. A new creds-free test pins that and the multi-term structure.
tests/timing/ore_block_256 runs by hand against a database with EQL installed (run.sh, DATABASE_URL). ctgen encrypts real legacy ORE ciphertexts with ore-rs under a throwaway key, so no CipherStash credentials are needed; it is a detached crate with its own workspace. The harness first checks the comparator against plaintext order on 1,500 pairs of 1-6 terms, then times two classes (operands that first differ early vs late) for single-term and six-term values through compare_ore_block_256_terms. Both classes share one randomly ordered table, each sample times several comparisons, and it reports the plain Welch t: separate per-class storage and percentile-cropped statistics each produced false signals in the ore.rs timing work. Against the previous comparator it reports t of -460 to -2575 for six-term values; against the current one every |t| is below 5.
🦋 Changeset detectedLatest commit: 9d5430e The changes in this PR will be included in the next version bump. This PR includes changesets to release 12 packages
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| Check name | Status | Explanation |
|---|---|---|
| Linked Issues check |  |
Issue #1149 requires constant operation count for single-term and multi-term ORE comparisons and a timing harness. functions.sql scans every block with fixed statement patterns, latches differences … |
| Out of Scope Changes check | |
The changed SQL directly implements issue #1149. The tests verify ordering, structure, and newly surfaced malformed-term errors. The timing harness, detached ciphertext generator, Dependabot entry, ch… |
| Docstring Coverage | |
Docstring coverage is 81.82% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 11 functions across 4 files. (5 skipped: 5 … |
| Description Check | |
Check skipped - CodeRabbit’s high-level summary is enabled. |
| Title check | |
The title clearly and concisely describes the main change: enforcing a constant operation count for the EQL ORE block comparator. |
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🟡 Changes recommended
Multi-term equality still changes the operation count, and fixed-width masks break otherwise valid wider terms.
3 open findings
What changed in this PR
Makes the EQL ORE comparator’s operation count independent of the first differing ciphertext block or term and adds a manual timing harness.
Changes:
- Reworks single- and multi-term comparator logic.
- Adds correctness coverage and timing infrastructure.
- Adds an EQL patch changeset.
| File | Description |
|---|---|
.changeset/eql-ore-block-256-constant-op-count.md |
Documents the security fix. |
packages/eql/src/v3/sem/ore_block_256/functions.sql |
Implements constant-operation comparison. |
packages/eql/tests/sqlx/tests/ore_block_comparator_tests.rs |
Updates comparator expectations. |
packages/eql/tests/sqlx/tests/encrypted_domain/family/sem.rs |
Tests multi-term structure and validation. |
packages/eql/tests/timing/ore_block_256/README.md |
Documents timing methodology. |
packages/eql/tests/timing/ore_block_256/run.sh |
Runs correctness and timing measurements. |
packages/eql/tests/timing/ore_block_256/harness.sql |
Implements sampling and Welch analysis. |
packages/eql/tests/timing/ore_block_256/ctgen/src/main.rs |
Generates ORE ciphertext samples. |
packages/eql/tests/timing/ore_block_256/ctgen/Cargo.toml |
Configures the detached generator crate. |
packages/eql/tests/timing/ore_block_256/ctgen/Cargo.lock |
Locks generator dependencies. |
packages/eql/tests/timing/ore_block_256/ctgen/.gitignore |
Excludes generator build output. |
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Code review (Claude Code,
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Review of the constant-operation-count comparator found three remaining data-dependent paths and a width limit: - When paired terms were all equal and the arrays had different term counts, the array comparator returned without hashing, so timing showed whether one value's terms are a prefix of the other's (about 7 µs against 9 µs). - When the first unequal pair had a NULL element, it also returned without hashing, so timing showed whether the terms before the NULL were equal. - The first differing block was read off a bitmask with round(ln(mask & -mask) / ln(2)). glibc's log() returns early for exactly 1.0, which is the first-block case, and the int4 mask failed at 32 or more blocks: "integer out of range" at 32, the wrong block at 33. The term comparator now latches the first differing block with one arithmetic statement per block (latch := latch + (latch = 0) * (block + 1) * differs): no mask, no float, no width limit. The array comparator compares each paired term whole in one statement (its PRP bytes and left blocks, the deterministic part) and latches the first unequal pair. It then calls compare_ore_block_256_term exactly once on every path: on the latched pair, or, when every pair is equal or the latched pair has a NULL element, on a NULL-free pair whose result is discarded. The result is selected arithmetically. This removes the copy of the block scan and hash from the array comparator, and every element is read once per iteration. A malformed term paired with a NULL element now raises too. Measured on PostgreSQL 17.11 (aarch64), through the operator path: single-term t = -0.78 and +0.48 (200k samples of 16), six-term t = +1.10 and -1.00 (50k samples of 8), and two new shapes at 100k samples of 8: an equal prefix of different-length arrays against a first-term difference, t = -0.45 and +0.79; a NULL after equal terms against a first-term difference, t = +0.26 and +1.24. A six-term comparison now takes about 18 µs either way (31 µs before this change); single-term comparisons cost about 6% more than the original comparator. Results are unchanged: 21,000 random arrays of 1-6 terms with NULL elements and truncation, and random terms of 8 to 64 blocks, give exactly what the original comparator gives, and the harness's 1,500 plaintext checks pass.
…ed paths Review follow-ups for the ORE block comparator work. - A creds-free ordering test (T4c in encrypted_domain/family/sem.rs). It encrypts u64 arrays in-process with ore-rs (the legacy 8-bit block scheme behind ore_block_256, already in the lockfile through cipherstash-client) under a fresh throwaway key, and checks every ordered pair against plaintext order: single terms first differing in each block, multi-term values sharing prefixes of every length, differences in early and late blocks of later terms, and a NULL second element against real terms. Nothing is committed and no CipherStash credentials are needed. Mutating the pair the comparator hashes, the block latch, or the NULL latch each fails it. - T4b builds its terms with ore-rs too, instead of synthetic blobs (its malformed term stays malformed on purpose). The module docs no longer describe the removed recursion. - The timing harness gains two classes for the paths the review found: an equal prefix of different-length arrays, and a NULL after equal terms, each against a first-term difference. Against the PR's first version they give t = -60 to -70; against the original comparator, +459 to +682; against the current one, |t| < 1 (50k samples of 8). - run.sh refuses to start if an ore_timing schema already exists, and drops only the schema it created. - Dependabot covers the ctgen crate's lockfile.
The harness comment called each sample's pairs distinct; they are drawn independently, with replacement, from a pool of the same size for both classes.
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- Files reviewed:
.changeset/eql-ore-block-256-constant-op-count.md,.github/dependabot.yml,packages/eql/Cargo.lock,packages/eql/src/v3/sem/ore_block_256/functions.sql,packages/eql/tests/sqlx/Cargo.toml,packages/eql/tests/sqlx/tests/encrypted_domain/family/sem.rs,packages/eql/tests/sqlx/tests/ore_block_comparator_tests.rs,packages/eql/tests/timing/ore_block_256/{README.md,run.sh,harness.sql,ctgen/*} - Models: Claude Sonnet 5.5 (
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The comparator logic itself (latch arithmetic, sign mapping, NULL and spare-pair selection) matched the original semantics on trace; the findings are behavior, coverage and doc issues.
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| bb := b[t].bytes; | ||
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| IF ab IS NOT NULL AND (octet_length(ab) <= 16 OR (octet_length(ab) - 16) % 49 != 0) THEN | ||
| RAISE EXCEPTION 'Malformed ORE term: % bytes', octet_length(ab); |
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Behavior change with availability impact: every paired term is now validated, so one malformed or mismatched-width term anywhere in a stored text value makes any comparison against it raise, even when the first terms already differ. Before, ORDER BY, index builds and index scans only raised if they reached the bad term. A single bad legacy row can now fail a whole ordered query or CREATE INDEX. The changeset mentions it, but there is no migration or lint path for finding such rows first.
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Addressed in 9d5430e. Since the bad term now raises where it used to be skipped, the changeset is now minor, and a new 3.1 upgrade guide (docs/upgrading/v3.1.md, U-001) gives the lint path you asked for: one query lists the term widths in a block-ORE text column (a clean column shows one well-formed width) and another finds the rows carrying any other width so they can be re-encrypted before upgrading. Both queries were run against a table holding a 407-byte term. Only payloads a CipherStash client did not produce can carry such a term.
| -- One hash and one bit read on every path. For equal terms this reads | ||
| -- block 0 and the result is discarded below. The hash key is the IV at | ||
| -- the start of b's right CT; the right blocks follow it. | ||
| indicator := ( |
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Equal terms now run encrypt() plus two get_bit() calls and a get_byte() (the result is discarded). Duplicates are common in btree builds, ORDER BY ties and equality probes on ORE columns. The quoted ~6% overhead was measured only on differing operands, and the harness has no equal-operands class for single terms, so the cost of this path is unmeasured.
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Measured, and the cost is real. Calling compare_ore_block_256_term directly on PostgreSQL 17.5 (Apple silicon, interleaved, 3 runs), equal terms take 3.6 µs with this PR against 2.7 µs on main, about 36% more. Differing terms take about 6% more. The README's cost paragraph (ec9c3de) and the changeset (9d5430e) now give both figures, and the README says that workloads with many ties should expect the larger one. The equal path has to hash, because skipping the hash for equal terms is exactly the timing difference this PR removes.
| differs := ((ab IS NULL) <> (bb IS NULL))::int; | ||
| null_order := (bb IS NULL)::int - (ab IS NULL)::int; | ||
| ELSE | ||
| IF octet_length(ab) != octet_length(bb) THEN |
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Inconsistent error precedence: the single-term comparator checks 'Ciphertexts are different lengths' before 'Malformed ORE term', but here the malformed checks (lines 305-310) run first. A pair like 100 bytes vs 408 bytes reports 'Malformed' in the array path and 'different lengths' in the term path. The 'different lengths' RAISE in this path is also not exercised by any added test (only the malformed case is).
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Fixed in 8aa3db0. The array path now checks the width before well-formedness, as the term comparator does, so both report 'Ciphertexts are different lengths' for a 407-byte term against a 408-byte one. Added tests for that pair and for a later pair of different widths (408 vs a well-formed 604) after an earlier unequal pair.
| -- Timing pairs. Both classes of a kind share one table in random order, so | ||
| -- neither sits in a fixed region of memory: with separate per-class storage, | ||
| -- placement alone produced a timing difference in the ore.rs benches. | ||
| CREATE TABLE pairs AS |
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Coverage gap: no class compares identical single terms (latch = 0) against terms that differ. That path was rewritten here (equal terms read block 0 and discard the hash), and an application user can issue equal-value probes. The prefix kind covers equal multi-term prefixes, but equal single terms against a first-block difference is never timed.
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Added in ec9c3de: an equal kind that compares a single term with itself, against pairs differing in the first block. 200k samples of 16 comparisons gave t = −2.49 and −1.99. On that machine equal terms are faster by about 6 ns per comparison, which is below the cost of one statement.
| // The first pair differs; the second is malformed. Every paired term is | ||
| // checked, so this raises rather than returning on the first pair. | ||
| let sql = cmp(arr(&[t, short]), arr(&[u, short])); | ||
| assert_raises(&pool, &sql, &[], "Malformed ORE term").await?; |
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Test gap: the multi-term structure test covers equal prefixes, NULL elements and a malformed later term, but not a later pair with different-width terms (for example N=8 vs N=12), which should raise 'Ciphertexts are different lengths' after an earlier unequal pair. It also has no NULL element paired with a malformed term, which is the case the changeset says now raises.
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Added in 8aa3db0: a later pair of different widths (N=8 against N=12) after an earlier unequal pair raises 'Ciphertexts are different lengths'. A malformed term paired with a NULL element raises 'Malformed ORE term', with the NULL on either side.
| ## Why it matters | ||
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| The comparator's inputs are ciphertexts, so the database operator learns | ||
| nothing from its timing: they can run the comparison themselves. The party |
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Ambiguous sentence: 'the database operator learns nothing from its timing: they can run the comparison themselves' leaves 'they' unclear (the operator? the ciphertext holders?). Say who can already compare the ciphertexts and why that makes timing uninformative to them.
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Reworded in ec9c3de: the database operator holds the stored ciphertexts and can run the comparator on any two of them directly, which tells them everything its timing could.
| # Everything lives in the ore_timing schema, which is dropped on exit. Refuse | ||
| # to start if it already exists, so a run never drops a schema it did not make. | ||
| if [ "$(psql "$DATABASE_URL" -tA -c "SELECT to_regnamespace('ore_timing') IS NOT NULL")" != "f" ]; then | ||
| echo "schema ore_timing already exists (or the database is unreachable); not touching it" >&2 |
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The probe conflates 'schema exists' with 'database unreachable' (a failed psql yields an empty string, which is also != 'f'). With set -e inside $(...) in a test, the real psql error is swallowed after being printed once. Check the psql exit status separately so a bad DATABASE_URL is reported as such.
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Fixed in ec9c3de. run.sh now checks psql's exit status separately and reports an unreachable database as itself, leaving psql's own error above it. The 'already exists' message is printed only when the query succeeds.
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| @@ -0,0 +1,15 @@ | |||
| --- | |||
| '@cipherstash/eql': patch | |||
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Use a minor changeset here: malformed multi-term payloads can now raise where they previously returned an ordering result, as the entry itself documents below. Shipping that tightened error behavior as a patch can break callers accepting patch upgrades and contradicts the repository's versioning policy for non-breaking behavior changes.
AGENTS.md reference: packages/eql/AGENTS.md:L284-L292
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Changed to minor in 9d5430e. The pending EQL changesets on main are already minor, so the next release is 3.1.0 either way.
| 18 µs whatever the operands. Multi-term (text) values now check every paired | ||
| term, so a malformed term after the first difference, or one paired with a NULL | ||
| element, raises instead of being skipped. A timing harness is in `packages/eql/tests/timing/ore_block_256/`. |
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Add a numbered upgrade note covering this new failure mode and cross-link it from the release entry. Applications with malformed later ORE terms, including terms paired with a NULL element, will now receive an exception where comparison previously short-circuited; the repository explicitly requires upgrade notes for tightened error semantics so callers can audit affected payloads.
AGENTS.md reference: packages/eql/AGENTS.md:L273-L282
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Added in 9d5430e: packages/eql/docs/upgrading/v3.1.md U-001, with a compatibility table, an audit query and the rows-to-re-encrypt query. The changeset links to it.
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Review comments at @packages/eql/tests/timing/ore_block_256/README.md:
- Around line 19-21: Replace the “every path” operation-count claim in the
README with a guarantee scoped to comparable operands of the same shape: the
count does not depend on the position of the first difference. In the changeset,
replace “whatever its operands” with the same scoped guarantee; do not imply
equal operation counts across different operand shapes.
- Around line 83-85: Correct the multi-term sample-count description in the
benchmark results: `run.sh` passes 50,000 samples total, which `bench`
distributes across classes. Remove “per class” or report the actual per-class
counts.
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.changeset/eql-ore-block-256-constant-op-count.md.github/dependabot.ymlpackages/eql/src/v3/sem/ore_block_256/functions.sqlpackages/eql/tests/sqlx/Cargo.tomlpackages/eql/tests/sqlx/tests/encrypted_domain/family/sem.rspackages/eql/tests/sqlx/tests/ore_block_comparator_tests.rspackages/eql/tests/timing/ore_block_256/README.mdpackages/eql/tests/timing/ore_block_256/ctgen/.gitignorepackages/eql/tests/timing/ore_block_256/ctgen/Cargo.tomlpackages/eql/tests/timing/ore_block_256/ctgen/src/main.rspackages/eql/tests/timing/ore_block_256/harness.sqlpackages/eql/tests/timing/ore_block_256/run.sh
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…omparator The multi-term path raised 'Malformed ORE term' for a pair that the term comparator reports as 'Ciphertexts are different lengths'. Both paths now check the width first. Tests cover a later pair of different widths after an earlier unequal pair, and a malformed term paired with a NULL element.
Adds an equal-term class to the ORE timing harness (a single term against itself, against a first-block difference) and records a second machine's results, including a small C-level difference in the prefix and NULL kinds there and the cost of hashing equal terms. run.sh now tells an unreachable database apart from an existing ore_timing schema. The README says who can already run the comparator, scopes the operation-count claim to operands of the same shape, and gives sample counts per kind rather than per class.
…rors Multi-term ORE values now raise on a malformed or mismatched-width term the comparator used to skip. That is a behaviour change, so the changeset is minor, and U-001 in a new 3.1 upgrade guide shows how to find such rows before upgrading.
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Review comments at @packages/eql/tests/timing/ore_block_256/README.md:
- Line 5: Update the README description of
`eql_v3_internal.compare_ore_block_256_terms` to say the harness tests for
detectable timing variation by first-difference position and equality class,
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|
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| Checks that `eql_v3_internal.compare_ore_block_256_terms`, the comparator | ||
| behind every ordered ORE operator and the ORE operator class, takes the same | ||
| time wherever its operands first differ, and whether they differ at all. |
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🎯 Functional Correctness | 🟡 Minor | ⚡ Quick win
Describe the timing measurement without claiming equal runtime.
Line 5 says the comparator takes the same time. Lines 20–29 limit the guarantee to operation count and note that lower-level timing effects remain. This wording could be read as a constant-time guarantee. Say that the harness tests for detectable timing differences by first-difference position and equality class.
Proposed wording
--- "a/packages/eql/tests/timing/ore_block_256/README.md"
+++ "b/packages/eql/tests/timing/ore_block_256/README.md"
@@ -1,8 +1,8 @@
# ORE comparator timing harness
-Checks that `eql_v3_internal.compare_ore_block_256_terms`, the comparator
-behind every ordered ORE operator and the ORE operator class, takes the same
-time wherever its operands first differ, and whether they differ at all.
+Checks whether `eql_v3_internal.compare_ore_block_256_terms`, the comparator
+behind every ordered ORE operator and the ORE operator class, shows detectable
+timing variation by first-difference position or equality class.
## Why it matters
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Review comment at @packages/eql/tests/timing/ore_block_256/README.md at line 5:
Update the README description of `eql_v3_internal.compare_ore_block_256_terms`
to say the harness tests for detectable timing variation by first-difference
position and equality class, rather than claiming equal runtime.
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Summary
The comparator change is correct, and its operation count is constant for operands of the same shape. One release problem blocks the merge: this PR changes the EQL 3.1.0 SQL bundle after stack-prisma baked that bundle on main.
What I checked
- Single term (
functions.sql:203-228). The loop bound isn, from the public width. Each iteration is one assignment.|and*are not short-circuit operators, and no operand can be NULL. After the loop,greatest,encrypt, twoget_bitcalls, oneget_bytecall andsignrun on every path. The result is the same as the old code for each of these cases: equal, first block differs, last block differs. - Multi term (
functions.sql:301-347). The onlyIFstatements test widths, well-formedness and NULL elements, which are all structure.sparechanges only when NULL positions change.hchanges with the data, but exactly one term comparison runs on every path. I traced these cases against the old recursion:[x,NULL]vs[x,y],[NULL,x]vs[NULL,y],[NULL]vs[NULL,y](hbecomes 0, so the call takes the NULL/NULL branch, which is structure), and prefixes of different lengths. All of them agree. - Call counts. I loaded
types.sqlandfunctions.sqlinto PostgreSQL 17 withtrack_functions = all. Then I readpg_stat_xact_user_functionsfor ten cases: single term equal, first block differs, last block differs; six terms equal, first term differs, last term differs; 5 vs 6 as a prefix and with a difference; and a NULL element after equal terms and after different terms. Every case gave exactlycompare_ore_block_256_terms=1,compare_ore_block_256_term=1andencrypt=1. - Index use. The signatures, the volatility and
operator_class.sqldid not change, so the planner uses the indexes as before. Only the cost per call changes. - v2/v4. Only
src/v3exists, so this PR covers the full set. - Changeset.
@cipherstash/eql: minoris in the root.changeset/. The version hook will rebuild the bundle on the 3.0.6 → 3.1.0 bump.
Blocking: the 3.1.0 bundle that stack-prisma baked becomes wrong
ae63dcd58 (on main) baked EQL 3.1.0 into stack-prisma before the Version Packages PR (#1054). It assumed that 3.1.0 changes only the version stamp:
languages/typescript/packages/stack-prisma/migrations/20261005T0000_upgrade_eql_v3_3_1_0/ops.jsonand the re-emitted baseline both contain the old comparator. I confirmed this:unequal_blockis in the baked SQL, andlatchis not.languages/typescript/packages/stack-prisma/test/v3/migration-v3.test.ts:159-170pins both toinstallSqlSha256 = af316179…..changeset/eql-3-1-0-migration.md:5-9says: "Its install SQL changes only the version stamp … No function, operator, domain or index behaviour changes."
After this PR merges, #1054 rebuilds the 3.1.0 bundle from this source. The digest then cannot be af316179. The lockstep test at migration-v3.test.ts:337 will fail on #1054, and that blocks the release. If someone only re-pins the digest, stack-prisma 1.3.0 ships a "3.1.0" migration that still contains the leaky comparator, and its changelog states that nothing changed.
Fix this in the same PR, or in a PR that merges together with it:
- Build the bundle with
--version 3.1.0 --forcefrom this branch. - Re-bake the 3.1.0 edge and the baseline from that bundle. Re-pin
migrationHashandinstallSqlSha256, and keepcreatedAt. Do the same inlanguages/typescript/examples/prisma/migrations/cipherstash/. - Correct
.changeset/eql-3-1-0-migration.mdso that it names the comparator change and links to U-001.
If you prefer, ship this change as 3.2.0 after 3.1.0 releases. But do not merge before #1054 unless step 2 happens.
Suggested follow-up PR
- No CI test holds the invariant. The ordering test proves correctness. The timing harness is manual and statistical. Thus a later edit can add an
IFon the data, and CI stays green. A creds-free sqlx test can doSET track_functions = 'all', run each class above in its own transaction, and assertencrypt= 1 andcompare_ore_block_256_term= 1 frompg_stat_xact_user_functions.SET track_functionsneeds a superuser (or aGRANT SETon it), so confirm the sqlx test role has that. I ran this check (see above), and it takes a few milliseconds. It does not count PL/pgSQL statements, but it catches the two regressions that matter most: a skipped hash and an extra hash. - Bench before release.
bench-eql.ymldid not run on this PR. The README gives +36% per comparison for equal single terms and about 18 µs per six-term text comparison. Run the bench once against ORDER BY and btree builds on a column with many duplicates, and put the figure in the U-001 note. Such a column runs mostly the equal path.
Summary
The ORE block comparator (
eql_v3_internal.compare_ore_block_256_term(s), behind every ordered ORE operator and the ORE operator class) took time that depended on where its operands first differ. A party who can time queries but cannot read the stored ciphertexts, such as an application user, could learn how long a prefix their query value shares with stored values. That is the information the constant-time comparator in ore.rs keeps from them. This PR makes the PL/pgSQL comparator run a constant number of operations for operands of the same shape (term count, term width, NULL positions), whether and wherever they differ, and adds a timing harness that measures it.PL/pgSQL is not a constant-time environment. The target here is a constant operation count: the same statements and function calls on every path. C-level effects inside those statements remain (
memcmpstopping early within 16 bytes, the offset asubstrreads at), orders of magnitude below one statement.What was wrong
ORshort-circuit skipped a comparison on each of those blocks. On the machine measured the two nearly cancel (t = +4.9 and +13.9). With the short-circuit removed, the extra statements alone gave t = +388, about 0.7 µs per comparison. Nothing guarantees the cancellation on other hardware or Postgres builds.Changes
packages/eql/src/v3/sem/ore_block_256/functions.sql|), and an arithmetic latch records the first differing block:latch := latch + (latch = 0)::int * (block + 1) * differs. Exactly oneencrypt(), twoget_bit()and oneget_byte()run on every path, equal terms included, and the result is selected arithmetically. Terms of any length work.compare_ore_block_256_termexactly once: on the latched pair, or on the first NULL-free pair when the order is settled by the term counts or a NULL element, and selects the result arithmetically. Term counts and NULL positions are public structure; they choose which pair is hashed but never whether the hash runs.tests/sqlx/.../family/sem.rs, no CipherStash credentials needed)packages/eql/tests/timing/ore_block_256/(see below), and itsctgencrate added todependabot.yml.@cipherstash/eqlminor, because of the new errors below. Upgrade note U-001 inpackages/eql/docs/upgrading/v3.1.mdshows how to find affected rows.Results
PostgreSQL 17.11, aarch64 (Docker on an Apple M1 Max), through
compare_ore_block_256_terms. Each column pits two classes of operands against each other;|t| < 5means no detectable difference. Current comparator: 200,000 single-term samples of 16 comparisons and 50,000 multi-term samples of 8 per class, two runs.¹ 5,000 samples per run. ² It scanned every block of every term, and skipped its hash when the term counts or a NULL settled the order (found in review). ³ 10,000 samples per run.
Cost: about 6% more per single-term comparison than before when the terms differ, and about 36% more (3.6 µs against 2.7 µs) when they are equal, because equal terms now run the hash too. About 18 µs per six-term comparison whatever the operands (before: 11–47 µs depending on the data).
Behaviour change
Multi-term values now check every paired term, including one paired with a NULL element, so a malformed or mismatched-width term after the first unequal one raises an error instead of being skipped. The width is checked before well-formedness, as in the term comparator, so both paths raise the same error. Results are otherwise unchanged.
Verification
mise run build,codegen:parity,test:self_contained_v3,docs:validateandtest:lintpass.Timing harness
DATABASE_URL=... packages/eql/tests/timing/ore_block_256/run.shruns by hand against any database with EQL installed. It needs no CipherStash credentials: a detachedctgencrate encrypts real legacy ORE ciphertexts with ore-rs under a throwaway key. It refuses to time a comparator that fails its correctness checks, and refuses to start if anore_timingschema already exists. It applies three lessons from timing work in ore.rs, each of which produced a false signal there:It is not wired into CI, because timing on shared runners is too noisy to gate on.
Code review findings and the plan for them: #1148 (comment)
Closes #1149
Summary by CodeRabbit