SPIKE memory usage difference between PG and Cloudberry

[my-ship-it]

We need to understand why Cloudberry occupies more memory than PG, and think is it possible to reduce memory?

PG memory usage

VmHWM:           13480 kB
VmRSS:           13480 kB
RssAnon:         452 kB
RssFile:         2308 kB
RssShmem:        10720 kB
VmData:          560 kB
VmStk:           132 kB
VmExe:           5892 kB
VmLib:           2624 kB
VmPTE:           112 kB

CBDB memory usage

VmHWM:           69304 kB
VmRSS:           69304 kB
RssAnon:            1552 kB
RssFile:            6908 kB
RssShmem:           60844 kB
VmData:            6212 kB
VmStk:             132 kB
VmExe:           12908 kB
VmLib:           15656 kB
VmPTE:             408 kB

And spike document link: https://hashdata.feishu.cn/docx/M3BLduwDzo4aJ5xcZT0cveKNnug