RE: Improve eviction algorithm in ReorderBuffer

Dear Sawada-san,

Thanks for making v3 patchset. I have also benchmarked the case [1].
Below results are the average of 5th, there are almost the same result
even when median is used for the comparison. On my env, the regression
cannot be seen.

HEAD (1e285a5)    HEAD + v3 patches    difference
10910.722 ms        10714.540 ms        around 1.8%

Also, here are mino comments for v3 set.

01.
bh_nodeidx_entry and ReorderBufferMemTrackState is missing in typedefs.list.

02. ReorderBufferTXNSizeCompare
Should we assert {ta, tb} are not NULL?

[1]: https://www.postgresql.org/message-id/CAD21AoB-7mPpKnLmBNfzfavG8AiTwEgAdVMuv%3DjzmAp9ex7eyQ%40mail.gmail.com

Best Regards,
Hayato Kuroda
FUJITSU LIMITED
https://www.fujitsu.com/