Fix documentation for tdigest_agg
The documentation incorrectly specified that the function takes 'accuracy'
argument when in fact the argument is 'compression factor'.
@@ -67,12 +67,14 @@ Functions
Returns the ``tdigest`` which is composed of all input values of ``x`` using
the per-item weight ``w``.
-.. function:: tdigest_agg(x, w, accuracy) -> tdigest<double>
+.. function:: tdigest_agg(x, w, compression) -> tdigest<double>
Returns the ``tdigest`` which is composed of all input values of ``x`` using
- the per-item weight ``w`` and maximum error of ``accuracy``. ``accuracy``
- must be a value greater than zero and less than one, and it must be constant
- for all input rows.
+ the per-item weight ``w`` and compression factor ``compression``. ``compression``
+ must be a value greater than zero, and it must be constant for all input rows.
+
+ Compression factor of 500 is a good starting point that typically yields good
+ accuracy and performance.
.. function:: destructure_tdigest(tdigest<double>) -> row<centroid_means array<double>, centroid_weights array<integer>, compression double, min double, max double, sum double, count bigint>
