[docs] Update ASOF join section in time-series tutorial

ryzhyk · ryzhyk · commit e2a1b7fd7168 · 2026-01-06T19:49:57.000Z
Signed-off-by: Leonid Ryzhyk &lt;ryzhyk@gmail.com&gt;
diff --git a/docs.feldera.com/docs/tutorials/time-series.md b/docs.feldera.com/docs/tutorials/time-series.md
@@ -655,13 +655,11 @@ ON purchase.customer_id = customer.customer_id;
 
 #### Garbage collection
 
-The incremental as-of join operator stores both of its input relations.  Feldera
-currently implements GC for the left input only: if both timestamp columns
-in the `MATCH_CONDITION` have waterlines, the operator will discard old records
-below the smaller of the two waterlines.
-
-GC for the right input is on our [roadmap](https://github.com/feldera/feldera/issues/1850).
-[Let us know](https://github.com/feldera/feldera/issues/new/) if you are interested in this feature.
+The incremental as-of join operator stores both of its input relations.  If both
+timestamp columns in the `MATCH_CONDITION` have waterlines, the operator will
+- discard records below the smaller of the two waterlines from the left collection
+- discard all except the last record below the smaller of the two waterlines for each join key
+  from the right collection.
 
 ### `LAG` and `LEAD`
 
