Re: WIP Patch for GROUPING SETS phase 1

The following review has been posted through the commitfest application:
make installcheck-world:  tested, failed
Implements feature:       tested, passed
Spec compliant:           not tested
Documentation:            tested, passed

Hi, 

I have (finally) found time to review this. 

The syntax is as per spec as I can see, and the queries I have tested have all produced the correct output. 

The documentation looks good and is clear.

I think it is spec compliant, but I am not used enough to the spec to be sure. Also I have not understood the function
of<set quantifier> (DISTINCT,ALL) part in the group by clause (and hence not tested it). Hence I haven't marked the
speccompliant part.
 

The installcheck-world fails, but in src/pl/tcl/results/pltcl_queries.out (a sorting problem when looking at the diff)
whichshould be unrelated to GSP. I don't know enough of the check to know if it has already run the GSP tests..
 

I have also been running a few tests on some real data. This is run on my laptop with 32 GB of memory and a fast SSD. 

The first dataset is a join between a data table of 472 MB (4,3 Mrows) and a tiny multi-column lookup table. I am
returninga count(*).
 
Here the data is hierarchical so CUBE does not make sense. GROUPING SETS and ROLLUP both works fine and if work_buffers
arelarge enough it slightly beats the handwritten "union all" equivalent (runtimes as 7,6 seconds  to 7,7 seconds). If
work_buffersare the default 4MB the union-all-equivalent (UAE) beats the GS-query almost 2:1 due to disk spill (14,3
(GS)vs. 8,2 (UAE) seconds). 
 

The other query is on the same datatable as before, but with three "columns" (two calculated and one natural) for a
cube.I am returning a count(*). 
 
First column is "extract year from date column"
Second column is "divide a value by something and truncate" (i.e. make buckets)
Third column is a litteral integer column. 
Here the GS-version is slightly slower than the UAE-version (17,5 vs. 14,2). Nothing obvious about why in the explain
(analyze,buffers,costs,timing).
 

I have the explains, but as the dataset is semi-private and I don't have any easy way to edit out names in it, I will
sendit on request (non-disclosure from the recipient is of course a must) and not post it on the list.
 

I think the feature is ready to be commited, but am unsure whether I am qualified to gauge that :)

/Svenne

The new status of this patch is: Ready for Committer