Why does the number of blocks for the table remain the sale after the shrink operation?
A.Because the table did not contain migrated or chained rows
B.Because the row IDs remain the same for all rows during the shrink operation
C.Because the progress of the shrink operation is not saved in the bitmap blocks of the table
D.Because the high-water mark (HWM) did not move due to the COMPACT option that is used in the shrink operation
ALTER TABLE table_name SHRINK SPACE COMPACT; --只压缩数据不下调HWM
HWM(High Water Mark) https://www.cnblogs.com/lijiaman/p/7190305.html?utm_source=itdadao&utm_medium=referral
某前辈的答案很多不一致，最后这个只能自己判断，尽量以官方答案为准来找理论依据。