Filed unassigned from the #6409 lane (the enforce half of #6188). Recording, not claiming — both packages are inside the #5499 investment freeze and #6409's ruling put them explicitly out of scope. This issue exists so the two open cells of the new AGGREGATION_CASES matrix column have a measured verdict behind them instead of an omission.
Context
#6409 lowered count_distinct to COUNT(DISTINCT x) on the SQL family and introduced AGGREGATION_CASES / AGGREGATION_ROWS (@objectstack/spec/data) — the shared standard the aggregate lowerings are now held to. Three of the five drivers were enrolled by that PR (driver-sql, driver-turso REMOTE, driver-sqlite-wasm). The other two carry DEBT rows in scripts/check-driver-conformance.mjs pointing here.
The standard's answer for count_distinct is distinct NON-NULL values of the target column — what COUNT(DISTINCT col) computes on SQLite, PostgreSQL and MySQL alike, and what objectql's in-memory fallback (in-memory-aggregation.ts, new Set(values.filter(v => v != null)).size) and service-analytics's AGGREGATE_SQL already give.
What each package answers today
Read from the source on origin/main @ 6de592c; not executed against the fixture, since neither cell has a suite (that is the debt).
1. driver-memory — the DATA face answers null, silently
MemoryDriver.computeAggregate (packages/drivers/driver-memory/src/memory-driver.ts) has arms for count, sum, avg, min, max and then:
There is no count_distinct arm. So aggregate() with { function: 'count_distinct', field: 'stage', alias: 'n' } resolves with { n: null } — no error, no log, no refusal. Against AGGREGATION_ROWS the standard says 2.
This is the worse half of the pair: a wrong ANSWER rather than a wrong number. It is also the default:-arm shape #4157 and the aggregation-lockstep guard in service-analytics exist to prevent one layer up, arriving here through a different door.
Note the package is partial in the way #6409's ruling described: its ANALYTICS face (memory-analytics.ts) does implement count_distinct ($addToSet, then sized). It is only the data-driver aggregate() path that has no arm — so this package answers one declared function two ways depending on which face you enter, the divergence class #5374 fixed for $contains in the same package.
2. driver-mongodb — counts NULL as a distinct value
mongodb-aggregation.ts lowers count_distinct to { $addToSet: fieldRef ?? null }, and postProcessAggregation takes the array's .length. $addToSet adds an explicit null to the set, so a column with rows won, won, lost, null, won, null sizes to 3 where the standard says 2.
$addToSet on a MISSING field adds nothing, so the divergence only shows for an explicitly-null value — which is exactly what AGGREGATION_ROWS seeds and exactly what a nullable column produces in practice.
Same file still carries a string_agg arm and a string_agg branch in postProcessAggregation; string_agg was retired from AggregationFunction at #6188, so that code is no longer reachable through a spec-valid request. Not a defect — noted so it is not rediscovered as one — and untouched for the same freeze reason.
Disposition
Deliberately none proposed. Both packages are #5499-frozen, so this is a decision about the freeze, not about the code: the fix on driver-memory is a count_distinct arm beside its neighbours, and on driver-mongodb a $ne: null filter before the $addToSet (or sizing a $setDifference against [null]). Neither is difficult; both are inside the boundary.
Clearing a cell means writing the suite that runs AGGREGATION_CASES and deleting the ledger row in the same PR — the gate fails either half alone. driver-mongodb's real-mongod suites are opt-in since #5517, so whatever clears its cell needs a server-free half in the shape of mongodb-filter-logic-translation.test.ts.
Refs: #6409 (the lane that measured this), #6188 (the split ruling), #5499 (the freeze), #6682 / #6520 (the same pair's other two open cells).
Filed unassigned from the #6409 lane (the enforce half of #6188). Recording, not claiming — both packages are inside the #5499 investment freeze and #6409's ruling put them explicitly out of scope. This issue exists so the two open cells of the new
AGGREGATION_CASESmatrix column have a measured verdict behind them instead of an omission.Context
#6409 lowered
count_distincttoCOUNT(DISTINCT x)on the SQL family and introducedAGGREGATION_CASES/AGGREGATION_ROWS(@objectstack/spec/data) — the shared standard the aggregate lowerings are now held to. Three of the five drivers were enrolled by that PR (driver-sql,driver-tursoREMOTE,driver-sqlite-wasm). The other two carry DEBT rows inscripts/check-driver-conformance.mjspointing here.The standard's answer for
count_distinctis distinct NON-NULL values of the target column — whatCOUNT(DISTINCT col)computes on SQLite, PostgreSQL and MySQL alike, and whatobjectql's in-memory fallback (in-memory-aggregation.ts,new Set(values.filter(v => v != null)).size) andservice-analytics'sAGGREGATE_SQLalready give.What each package answers today
Read from the source on
origin/main@6de592c; not executed against the fixture, since neither cell has a suite (that is the debt).1.
driver-memory— the DATA face answersnull, silentlyMemoryDriver.computeAggregate(packages/drivers/driver-memory/src/memory-driver.ts) has arms forcount,sum,avg,min,maxand then:There is no
count_distinctarm. Soaggregate()with{ function: 'count_distinct', field: 'stage', alias: 'n' }resolves with{ n: null }— no error, no log, no refusal. AgainstAGGREGATION_ROWSthe standard says2.This is the worse half of the pair: a wrong ANSWER rather than a wrong number. It is also the
default:-arm shape #4157 and theaggregation-lockstepguard inservice-analyticsexist to prevent one layer up, arriving here through a different door.Note the package is partial in the way #6409's ruling described: its ANALYTICS face (
memory-analytics.ts) does implementcount_distinct($addToSet, then sized). It is only the data-driveraggregate()path that has no arm — so this package answers one declared function two ways depending on which face you enter, the divergence class #5374 fixed for$containsin the same package.2.
driver-mongodb— counts NULL as a distinct valuemongodb-aggregation.tslowerscount_distinctto{ $addToSet: fieldRef ?? null }, andpostProcessAggregationtakes the array's.length.$addToSetadds an explicitnullto the set, so a column with rowswon, won, lost, null, won, nullsizes to 3 where the standard says 2.$addToSeton a MISSING field adds nothing, so the divergence only shows for an explicitly-null value — which is exactly whatAGGREGATION_ROWSseeds and exactly what a nullable column produces in practice.Same file still carries a
string_aggarm and astring_aggbranch inpostProcessAggregation;string_aggwas retired fromAggregationFunctionat #6188, so that code is no longer reachable through a spec-valid request. Not a defect — noted so it is not rediscovered as one — and untouched for the same freeze reason.Disposition
Deliberately none proposed. Both packages are #5499-frozen, so this is a decision about the freeze, not about the code: the fix on
driver-memoryis acount_distinctarm beside its neighbours, and ondriver-mongodba$ne: nullfilter before the$addToSet(or sizing a$setDifferenceagainst[null]). Neither is difficult; both are inside the boundary.Clearing a cell means writing the suite that runs
AGGREGATION_CASESand deleting the ledger row in the same PR — the gate fails either half alone.driver-mongodb's real-mongod suites are opt-in since #5517, so whatever clears its cell needs a server-free half in the shape ofmongodb-filter-logic-translation.test.ts.Refs: #6409 (the lane that measured this), #6188 (the split ruling), #5499 (the freeze), #6682 / #6520 (the same pair's other two open cells).