Thanks! On Thu, Apr 16, 2020 at 9:57 PM ZHANG Wei <wezh...@outlook.com> wrote:
> Are you looking for this: > https://spark.apache.org/docs/2.4.0/api/sql/#when ? > > The code generated will look like this in a `do { ... } while (false)` > loop: > > do { > ${cond.code} > if (!${cond.isNull} && ${cond.value}) { > ${res.code} > $resultState = (byte)(${res.isNull} ? $HAS_NULL : $HAS_NONNULL); > ${ev.value} = ${res.value}; > continue; > } > > <and the following CASE conditions ...> > } while (false) > > Refer to: > https://github.com/apache/spark/blob/master/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/conditionalExpressions.scala#L208 > > Here is a full generated code sample for `spark.sql("select CASE WHEN age > IS NULL THEN 'unknown' WHEN age < 30 THEN 'young' WHEN age < 40 THEN > 'middle' ELSE 'senior' END, name from people").show()` : > > /* 034 */ byte project_caseWhenResultState_0 = -1; > /* 035 */ do { > /* 036 */ if (!false && scan_isNull_0) { > /* 037 */ project_caseWhenResultState_0 = (byte)(false ? 1 : 0); > /* 038 */ project_mutableStateArray_0[0] = ((UTF8String) > references[1] /* literal */); > /* 039 */ continue; > /* 040 */ } > /* 041 */ > /* 042 */ boolean project_isNull_4 = true; > /* 043 */ boolean project_value_4 = false; > /* 044 */ > /* 045 */ if (!scan_isNull_0) { > /* 046 */ project_isNull_4 = false; // resultCode could change > nullability. > /* 047 */ project_value_4 = scan_value_0 < 30L; > /* 048 */ > /* 049 */ } > /* 050 */ if (!project_isNull_4 && project_value_4) { > /* 051 */ project_caseWhenResultState_0 = (byte)(false ? 1 : 0); > /* 052 */ project_mutableStateArray_0[0] = ((UTF8String) > references[2] /* literal */); > /* 053 */ continue; > /* 054 */ } > /* 055 */ > /* 056 */ boolean project_isNull_8 = true; > /* 057 */ boolean project_value_8 = false; > /* 058 */ > /* 059 */ if (!scan_isNull_0) { > /* 060 */ project_isNull_8 = false; // resultCode could change > nullability. > /* 061 */ project_value_8 = scan_value_0 < 40L; > /* 062 */ > /* 063 */ } > /* 064 */ if (!project_isNull_8 && project_value_8) { > /* 065 */ project_caseWhenResultState_0 = (byte)(false ? 1 : 0); > /* 066 */ project_mutableStateArray_0[0] = ((UTF8String) > references[3] /* literal */); > /* 067 */ continue; > /* 068 */ } > /* 069 */ > /* 070 */ project_caseWhenResultState_0 = (byte)(false ? 1 : 0); > /* 071 */ project_mutableStateArray_0[0] = ((UTF8String) > references[4] /* literal */); > /* 072 */ > /* 073 */ } while (false); > > > Cheers, > -z > ________________________________________ > From: Yeikel <em...@yeikel.com> > Sent: Wednesday, April 15, 2020 2:22 > To: user@spark.apache.org > Subject: Re: How does spark sql evaluate case statements? > > I do not know the answer to this question so I am also looking for it, but > @kant maybe the generated code can help with this. > > > > -- > Sent from: http://apache-spark-user-list.1001560.n3.nabble.com/ > > --------------------------------------------------------------------- > To unsubscribe e-mail: user-unsubscr...@spark.apache.org > > > --------------------------------------------------------------------- > To unsubscribe e-mail: user-unsubscr...@spark.apache.org > >
