group() built-in function in DaphneDSL
#903
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- This built-in function creates a GroupOp in DaphneIR. - Only support 'SUM' as an aggregation function. - Get only one aggregation column. - Get an arbitrary number of columns to group on. - Add support for string values in the 'group' kernel function. - SUM, MIN, and MAX are the only aggregation functions applied to string columns. - Other aggregation functions throw an exception if they receive strings as arguments or results. - Additionally, 'DeduceValueTypeAndExecute' cannot handle string values due to unsupported operations on strings. - Therefore, 'ColumnGroupAggStringVTArg' that is specialized for strings is used. - Or 'ColumnGroupAgg' is called exclusively with string values. - The 'group' function internally calls the 'order' and 'extractCol' kernel functions. - These two functions are updated to handle string values correctly. - Added script-level test cases to validate the new functionality. - Close issue daphne-eu#903
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DaphneIR has a
GroupOpfor relational-style grouping and aggregation, plus a correspondinggroup-kernel. However, at the moment, this operation can only be created through DAPHNE's SQL parser, but not through DaphneDSL.This task is to add a
group()built-in function to DaphneDSL that creates aGroupOpin DaphneIR. The interface should be (following the notation used in the docs:group(arg:frame, groupCols:str, ..., sumCol:str). That is, the built-in function gets a frame, an arbitrary number of columns to group on, and a single column to calculate the sum on. While this interface does not allow to use all features of theGroupOp/group-kernel (e.g., multiple aggregates, other aggregate functions than sum), it would be a good first step and sufficient for implementing the Star Schema Benchmark in DaphneDSL. We can reflect the full functionality of theGroupOpis DaphneDSL later.Hints:
groupbuilt-in function.groupis a variadic built-in/op/kernel. See existing ops likecreateFramefor an example. E.g., have a look at how they are handled insrc/parser/daphnedsl/DaphneDSLBuiltins.cpp.GroupOp, see the SQL parser insrc/parser/sql/SQLVisitor.cpp.The text was updated successfully, but these errors were encountered: