From 0daeb830b0f0e078d34aaec8e7b87f9ae74c579f Mon Sep 17 00:00:00 2001 From: Himanshu Gupta Date: Wed, 19 Aug 2015 15:20:37 -0500 Subject: [PATCH] update approx-histogram document to explain how to ignore rows with no value at ingestion time --- docs/content/development/approximate-histograms.md | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/docs/content/development/approximate-histograms.md b/docs/content/development/approximate-histograms.md index 58822336de5..2df94198fd8 100644 --- a/docs/content/development/approximate-histograms.md +++ b/docs/content/development/approximate-histograms.md @@ -44,14 +44,17 @@ especially with long tails, since that's where the approximation will be worse. ### Creating approxiate histogram sketches at ingestion time -To use this feature, an "approxHistogram" aggregator must be included at -indexing time. The ingestion aggregator can only apply to numeric values. To -query for results, an "approxHistogramFold" aggregator must be included in the +To use this feature, an "approxHistogram" or "approxHistogramFold" aggregator must be included at +indexing time. The ingestion aggregator can only apply to numeric values. If you use "approxHistogram" +then any input rows missing the value will be considered to have a value of 0, while with "approxHistogramFold" +such rows will be ignored. + +To query for results, an "approxHistogramFold" aggregator must be included in the query. ```json { - "type" : "approxHistogram(ingestion), approxHistogramFold(query)", + "type" : "approxHistogram or approxHistogramFold (at ingestion time), approxHistogramFold (at query time)", "name" : , "fieldName" : , "resolution" : ,