dtenedor commented on code in PR #55629:
URL: https://github.com/apache/spark/pull/55629#discussion_r3183430584
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docs/sql-ref-syntax-qry-select-join.md:
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@@ -53,6 +53,30 @@ relation { [ join_type ] JOIN [ LATERAL ] relation [
join_criteria ] | NATURAL j
Specifies an expression with a return type of boolean.
+* **nearest_by_clause**
+
+ Specifies a nearest-by top-K ranking join. For each row on the left (query
side), returns up to `num_results` rows from the right (base side), ranked by
`ranking_expression`. Only `INNER` (the default) and `LEFT OUTER` join types
are supported with this clause.
+
+ **Syntax:** `{ APPROX | EXACT } NEAREST [ num_results ] BY { DISTANCE |
SIMILARITY } ranking_expression`
+
+ `APPROX | EXACT`
+
+ Controls the search algorithm contract. `APPROX` allows the optimizer to
use faster approximate strategies (such as indexed nearest-neighbor search when
available). `EXACT` forces brute-force evaluation and requires
`ranking_expression` to be deterministic.
+
+ `num_results`
+
+ A positive integer literal between 1 and 100000 that limits the number of
matches per left row. Defaults to 1 when omitted.
Review Comment:
Why this limit? Is it controlled by a config?
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