[jira] [Assigned] (SPARK-42775) approx_percentile produces wrong results for large decimals.
[ https://issues.apache.org/jira/browse/SPARK-42775?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Apache Spark reassigned SPARK-42775: Assignee: (was: Apache Spark) > approx_percentile produces wrong results for large decimals. > > > Key: SPARK-42775 > URL: https://issues.apache.org/jira/browse/SPARK-42775 > Project: Spark > Issue Type: Bug > Components: SQL >Affects Versions: 2.1.0, 2.2.0, 2.3.0, 2.4.0, 3.0.0, 3.1.0, 3.2.0, 3.3.0, > 3.4.0 >Reporter: Chenhao Li >Priority: Major > > In the {{approx_percentile}} expression, Spark casts decimal to double to > update the aggregation state > ([ApproximatePercentile.scala#L181|https://github.com/apache/spark/blob/933dc0c42f0caf74aaa077fd4f2c2e7208452b9b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/ApproximatePercentile.scala#L181]) > and casts the result double back to decimal > ([ApproximatePercentile.scala#L206|https://github.com/apache/spark/blob/933dc0c42f0caf74aaa077fd4f2c2e7208452b9b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/ApproximatePercentile.scala#L206]). > The precision loss in the casts can make the result decimal out of its > precision range. This can lead to the following counter-intuitive results: > {code:sql} > spark-sql> select approx_percentile(col, 0.5) from values > (999) as tab(col); > NULL > spark-sql> select approx_percentile(col, 0.5) is null from values > (999) as tab(col); > false > spark-sql> select cast(approx_percentile(col, 0.5) as string) from values > (999) as tab(col); > 1000 > spark-sql> desc select approx_percentile(col, 0.5) from values > (999) as tab(col); > approx_percentile(col, 0.5, 1)decimal(19,0) > {code} > The result is actually not null, so the second query returns false. The first > query returns null because the result cannot fit into {{{}decimal(19, 0){}}}. > A suggested fix is to use {{Decimal.changePrecision}} here to ensure the > result fits, and really returns a null or throws an exception when the result > doesn't fit. -- This message was sent by Atlassian Jira (v8.20.10#820010) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org
[jira] [Assigned] (SPARK-42775) approx_percentile produces wrong results for large decimals.
[ https://issues.apache.org/jira/browse/SPARK-42775?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Apache Spark reassigned SPARK-42775: Assignee: Apache Spark > approx_percentile produces wrong results for large decimals. > > > Key: SPARK-42775 > URL: https://issues.apache.org/jira/browse/SPARK-42775 > Project: Spark > Issue Type: Bug > Components: SQL >Affects Versions: 2.1.0, 2.2.0, 2.3.0, 2.4.0, 3.0.0, 3.1.0, 3.2.0, 3.3.0, > 3.4.0 >Reporter: Chenhao Li >Assignee: Apache Spark >Priority: Major > > In the {{approx_percentile}} expression, Spark casts decimal to double to > update the aggregation state > ([ApproximatePercentile.scala#L181|https://github.com/apache/spark/blob/933dc0c42f0caf74aaa077fd4f2c2e7208452b9b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/ApproximatePercentile.scala#L181]) > and casts the result double back to decimal > ([ApproximatePercentile.scala#L206|https://github.com/apache/spark/blob/933dc0c42f0caf74aaa077fd4f2c2e7208452b9b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/ApproximatePercentile.scala#L206]). > The precision loss in the casts can make the result decimal out of its > precision range. This can lead to the following counter-intuitive results: > {code:sql} > spark-sql> select approx_percentile(col, 0.5) from values > (999) as tab(col); > NULL > spark-sql> select approx_percentile(col, 0.5) is null from values > (999) as tab(col); > false > spark-sql> select cast(approx_percentile(col, 0.5) as string) from values > (999) as tab(col); > 1000 > spark-sql> desc select approx_percentile(col, 0.5) from values > (999) as tab(col); > approx_percentile(col, 0.5, 1)decimal(19,0) > {code} > The result is actually not null, so the second query returns false. The first > query returns null because the result cannot fit into {{{}decimal(19, 0){}}}. > A suggested fix is to use {{Decimal.changePrecision}} here to ensure the > result fits, and really returns a null or throws an exception when the result > doesn't fit. -- This message was sent by Atlassian Jira (v8.20.10#820010) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org