Streams: Support subqueries with multiple parameters

[simolus3]

Evaluating streams using subqueries with multiple parameters is currently broken in two ways. To illustrate this, consider this example taken from a report on Discord:

SELECT *
FROM "Scene"
WHERE
  project IN (
    SELECT project
    FROM "ProjectInvitation"
    WHERE
    AND (auth.parameters() ->> 'haystack_id') IN "appliedTo"
    AND project = subscription.parameter('project')
  )

This subquery has two parameter match clauses: the IN operator and the direct equals.

The first issue is that we used to compute the WHERE clause of the subquery with SqlTools.compileClause. That method will merge the AND into a single ParameterMatchClause, which is valid for bucket definitions but not for streams! Since each parameter is an explicit object with streams, this would cause two parameters to be derived from the same ParameterMatchClause, which then causes values for the two parameters to get duplicated:

• Before: evaluateParameterRow(projectInvitation, {project: 'p', appliedTo: '[1,2]'}) yields lookup with keys [1,p], [1,p], [2, p], [2, p].
• After: Yields lookup with keys [1, p], [2, p].

The reason we used compileClause is that we only support a subset of filter operators for WHERE clauses in subqueries, and those happened to align with what SqlTools.compileClause would support. So the first part of the fix is to compile subquery predicates with the same logic as we compile the outer query, and then applying a validator to ensure there are no nested subqueries or other unsupported filters.

A second issue is that StreamVariant.findStaticInstantiations (used in Subquery.compileEvaluator) was missing a transform from "list of values per parameter" to "list of lookups" via the cartesian product. That's only relevant for subqueries with more than one parameter:

• Before: Would attempt to lookup [1], [p].
• After: Looks up the correct key [1, p].

[changeset-bot]

🦋 Changeset detected

Latest commit: 9870e89

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 17 packages

Name	Type
@powersync/service-sync-rules	Patch
@powersync/service-jpgwire	Patch
@powersync/service-core-tests	Patch
@powersync/service-core	Patch
@powersync/lib-services-framework	Patch
@powersync/service-module-mongodb-storage	Patch
@powersync/service-module-mongodb	Patch
@powersync/service-module-mysql	Patch
@powersync/service-module-postgres-storage	Patch
@powersync/service-module-postgres	Patch
@powersync/lib-service-postgres	Patch
@powersync/service-module-core	Patch
@powersync/service-image	Patch
test-client	Patch
@powersync/service-rsocket-router	Patch
@powersync/lib-service-mongodb	Patch
@powersync/service-schema	Patch

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