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new 3487663 Adjust approx agg deprecation wording (#7518)
3487663 is described below
commit 3487663de953eef4090f092fdfe173c0242936b8
Author: Jonathan Wei <[email protected]>
AuthorDate: Fri Apr 19 19:31:50 2019 -0700
Adjust approx agg deprecation wording (#7518)
---
docs/content/querying/aggregations.md | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/docs/content/querying/aggregations.md
b/docs/content/querying/aggregations.md
index 939e1b7..23b333f 100644
--- a/docs/content/querying/aggregations.md
+++ b/docs/content/querying/aggregations.md
@@ -282,14 +282,18 @@ Compared to the Theta sketch, the HLL sketch does not
support set operations and
#### Cardinality/HyperUnique (Deprecated)
<div class="note caution">
-The Cardinality and HyperUnique aggregators are deprecated. Please use <a
href="../development/extensions-core/datasketches-theta.html">DataSketches
Theta Sketch</a> or <a
href="../development/extensions-core/datasketches-hll.html">DataSketches HLL
Sketch</a> instead.
+The Cardinality and HyperUnique aggregators are deprecated.
+For new use cases, we recommend evaluating <a
href="../development/extensions-core/datasketches-theta.html">DataSketches
Theta Sketch</a> or <a
href="../development/extensions-core/datasketches-hll.html">DataSketches HLL
Sketch</a> instead.
+For existing users, we recommend evaluating the newer DataSketches aggregators
and migrating if possible.
</div>
The [Cardinality and HyperUnique](../querying/hll-old.html) aggregators are
older aggregator implementations available by default in Druid that also
provide distinct count estimates using the HyperLogLog algorithm. The newer
DataSketches Theta and HLL extension-provided aggregators described above have
superior accuracy and performance and are recommended instead.
The DataSketches team has published a [comparison
study](https://datasketches.github.io/docs/HLL/HllSketchVsDruidHyperLogLogCollector.html)
between Druid's original HLL algorithm and the DataSketches HLL algorithm.
Based on the demonstrated advantages of the DataSketches implementation, we
have deprecated Druid's original HLL aggregator.
-Please note that `hyperUnique` aggregators are not mutually compatible with
Datasketches HLL or Theta sketches.
+Please note that `hyperUnique` aggregators are not mutually compatible with
Datasketches HLL or Theta sketches.
+
+Although deprecated, we will continue to support the older
Cardinality/HyperUnique aggregators for backwards compatibility.
##### Multi-column handling
@@ -324,6 +328,11 @@ We do not recommend the fixed buckets histogram for
general use, as its usefulne
#### Approximate Histogram (Deprecated)
+<div class="note caution">
+The Approximate Histogram aggregator is deprecated.
+We recommend using <a
href="../development/extensions-core/datasketches-quantiles.html">DataSketches
Quantiles</a> instead.
+</div>
+
The [Approximate
Histogram](../development/extensions-core/approximate-histograms.html)
extension-provided aggregator also provides quantile estimates and histogram
approximations, based on
[http://jmlr.org/papers/volume11/ben-haim10a/ben-haim10a.pdf](http://jmlr.org/papers/volume11/ben-haim10a/ben-haim10a.pdf).
The algorithm used by this deprecated aggregator is highly
distribution-dependent and its output is subject to serious distortions when
the input does not fit within the algorithm's limitations.
@@ -335,7 +344,7 @@ A [study published by the DataSketches
team](https://datasketches.github.io/docs
It is not possible to determine a priori how well this aggregator will behave
for a given input stream, nor does the aggregator provide any indication that
serious distortions are present in the output.
-For these reasons, we have deprecated this aggregator and do not recommend its
use.
+For these reasons, we have deprecated this aggregator and recommend using the
DataSketches Quantiles aggregator instead for new and existing use cases,
although we will continue to support Approximate Histogram for backwards
compatibility.
## Miscellaneous Aggregations
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