Join Lab

See What A Join Does Before It Reaches The Dashboard

Two movable data planes meet at a Join Hinge. Switch cardinality across One-to-One, One-to-Many, and Many-to-Many — planes unfold differently, fanout ghosts duplicate original records, and SUM, COUNT, and AVERAGE recalculate live.

customers · 6,412 rows
One-to-Many
contacts · 14,738 rows
One-to-One One-to-Many Many-to-Many
SUM$612,400
COUNT14,738
AVERAGE$41.53

At One-to-One these read $482,900 · 6,412 · $75.34 — Change Cardinality to watch fanout unfold.

A Correct Query Can Still Produce The Wrong Metric.

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