Dear：
According to grammar : alter index to USABLE will cause the index to
again be considered for use in queries.
But this contract fail if we do:
1. Create table s.t (k varchar not null primary key, v1 varchar, v2
varchar)
2. Create index i on s.t (v1) include (v2)
3. Explain select * from s.t order by v1 ---> CLIENT PARALLEL 1-WAY
FULL SCAN OVER S.I
4. Alter index I on s.t usable
5. Explain select * from s.t order by v1 --->
CLIENT PARALLEL 1-WAY FULL SCAN OVER S.T
SERVER SORTED BY [V1]
CLIENT MERGE SORT
In step 5 index is not considered because it’s state is “usable”
instead of “active”.
After looking into the code, I have few more questions:
1. What’s the different between ‘usable’ and ‘active’, and the
same question with ‘unusable’ and ‘inactive’
2. I saw two index building path:
One in method buildIndex where the state transition is “ disable
-> building -> active “
The other in method buildPartialIndexFromTimeStemp where the state
transition is “ disable -> inactive -> active “
So What’s the different between ‘building’ and ‘inactive’
Thanks in advance
Daniel.meng
