New functions for calculations on the dimension of rows: rowMin, rowMax, rowCount, rowSum, rowSum2, rowAvg, rowStd, rowVar
Extended SQL PIVOT BY clause to make pivoting, null filling and row level reductive operation complete in one step. Right now, "pivot by" can be used together with ffill, fill, and lfill, as well as the following 5 row-dimension functions: rowSum, rowMin, rowMax, rowCount, rowSum2.
New higher order function pcall
New function subtuple
Improvements
Optimize the performance of return statement to avoid unnecessary data copy
