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https://issues.apache.org/jira/browse/SOLR-10332?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15936376#comment-15936376
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Joel Bernstein edited comment on SOLR-10332 at 3/22/17 2:16 PM:
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While testing the SQL interface I also ran across strange results when
performing min/max on the _version_ field which is a long. The stats component
appears to treat longs as doubles and then has floating point errors which
return incorrect long values.
I think it makes sense to review how numbers are being handled by stats
component and compare it with faceting.
was (Author: joel.bernstein):
While testing the SQL interface I also ran across strange results when
performing min/max on the _version_ field which is a long. The stats component
appears to treat longs as doubles and then has floating point errors which
return incorrect long values.
I think makes sense to review how numbers are being handled component and
compare it with faceting.
> Rounding errors in min/max statistics for a currency field/currency conversion
> ------------------------------------------------------------------------------
>
> Key: SOLR-10332
> URL: https://issues.apache.org/jira/browse/SOLR-10332
> Project: Solr
> Issue Type: Bug
> Security Level: Public(Default Security Level. Issues are Public)
> Affects Versions: 6.4.1, 6.4.2
> Reporter: Kirill A.
>
> There are rounding errors in the Stats component of Solr while requesting
> min/max statistics for a currency field.
> Description:
> I have a currency field price in the Solr index. Here is the schema
> definition:
> <fieldType name="currency" class="solr.CurrencyField"
> currencyConfig="currency.xml" defaultCurrency="EUR" precisionStep="8"/>
> <field name="price" type="currency" multiValued="false" indexed="true"
> required="false" stored="true"/>
> Sending a stats query to get the min/man price in the result set leads to
> rounding errors for index documents with a price with certain digits after
> the decimal point.
> The following stats-string is used in the stats query:
> {code:title=Stats-string|borderStyle=solid}
> stats=true&stats.field={!func}currency(price,EUR)
> {code}
> Example 1:
> Index document with
> "price":"209.90000,EUR"
> Stats query only for this document (with additional fq-filter using the id)
> returns:
> "stats":{
> "stats_fields":{
> "currency(price,EUR)":{
> "min":209.89999389648438,
> "max":209.89999389648438,
> ...
> Example 2:
> Index document with
> "price":"295.95000,EUR",
> Stats query only for this document (with additional fq-filter using the id)
> returns:
> "stats":{
> "stats_fields":{
> "currency(price,EUR)":{
> "min":295.95001220703125,
> "max":295.95001220703125,
> ...
> Now if you want to determine a price range to show to the user (min and max
> price in the index for the current constraints), you can not safely use the
> stats function: if you round the result 295.95001220703125 to a price with
> two digits after the decimal point you get: 295.95. Now if you use 295.95 as
> the max price of the range, you will not find documents which actually have a
> price 295.95001220703125 and not 295.95000 in the second example. The stats
> function returned 295.95001220703125 but we don't know if it is a rounding
> error or a real price. Note, that if a price has a different currency, the
> conversion to EUR (default currency) can also produce a result with a lot of
> decimal places so you have to rely on accuracy of the stats function.
> So it is not a solution to round an inaccurate result to determine the max
> price (if you round the inaccurate result down, you get 295.95 but you will
> not find documents with an other currency equal to for example 295.951 EUR,
> so you should not round down. If you round the inaccurate result up you get:
> 295.96 but it is not the real price of the document in the second example).
> The min and max stats function should return an accurate result (example 1:
> 209.9 EUR, example 2: 295.95 EUR)
> The SolrJ interface of Solr in Java returns a result of min/max stats
> function as double, but double can provide inaccurate results for currency
> fields and currency conversion, please consider using BigDecimal.
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