routier-collection

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routier-collection / plugins/sql-core/src / canPushDownJoin

Function: canPushDownJoin()

canPushDownJoin(join, dialect?, divergentCalls?): boolean

Defined in: plugins/sql-core/src/joins.ts:175

Whether every filter of the inner side can be expressed in SQL, by this dialect.

A plugin must ask this BEFORE claiming a join was pushed down. Two ways the answer is no:

• core marked an inner filter memory-only — an unmapped property — so there is no column to compare and the statement would silently return rows the scope excludes. A renamed property is not one: it renders its storage column, qualified by the inner alias, like any other;
• the filter holds a call this ENGINE cannot render. The main read path asks canRenderInSql before translating, and without the same question here a join was the one way to reach a renderer for a call the dialect does not claim.

dialect is optional so an existing caller keeps its meaning; passing it is what closes the second hole.

Parameters

join

kind

JoinKind

innerSchemaId

SchemaId

Resolved through event.schemas, which already carries every schema in the store.

outerKey

JoinKeyReference

innerKey

JoinKeyReference

innerOptions

QueryOptionsCollection<any>

The inner side's own filters — INCLUDING its soft-delete scope and .scope() filters. Every interpreter must apply these: it is the only place they exist, because a join bypasses the inner collection's normal read path.

crossPlugin

boolean

Whether the two sides live on DIFFERENT plugin instances, in which case no plugin can receive the option and the datastore is the interpreter.

Decided by plugin instance identity at build time, never by comparing database names — two plugins over one database are still two interpreters, and one name can front two databases.

semiJoinKeyThreshold

number

How many distinct outer keys are still worth turning into an IN (...) prefilter on the inner read — the datastore's semiJoinKeyThreshold, default 500.

Carried in the option because the decision is made where the join executes, which is usually inside a plugin, and a plugin cannot see a datastore's configuration. A number serializes; a reference to the store would not.

Cost only. Above the threshold the inner side is read under its own scopes and the hash join discards the surplus — the same answer by a slower route.

dialect?

SqlDialectName | SqlDialect

divergentCalls?

readonly Call[] = []

Returns

boolean