Use cudf to compute exact hash join output row sizes

[jlowe]

Fixes #2440

Removes the hash join code to estimate the join size and replaces it with the cudf output join size APIs. This also removes the OOM catch-and-retry logic since it theoretically should no longer be necessary since we are no longer producing an estimate but instead an exact amount.

Posting as a draft for the following reasons:

• Depends on fix for [BUG] cudf::hash_join compute size fails on struct columns rapidsai/cudf#9095
• Depends on fix for [BUG] cudf::hash_join throws exception when computing inner join size of empty build table rapidsai/cudf#9092
• Need to validate performance gain by removing estimation code

[revans2]

From the look of things it appears that the builtHash does not out live a single batch being returned. The rest of the changes look good.

[jlowe]

From the look of things it appears that the builtHash does not out live a single batch being returned.

Yeah, the built hash isn't spillable, and the code tries to make everything spillable before it produces a batch. Therefore I thought it prudent to throw away the built hash to avoid a potential OOM.

[jlowe]

build

[jlowe]

I ran Q75 which has quite a few joins in it at SF=100 on my local desktop. It's in the ballpark of 5% faster, around 33 seconds before and 31.5 seconds after. I verified with an Nsight Systems trace that the hash table is getting re-used between the output size and join calculations for an individual batch.