a question about log in IOTypeLongArray

[yuan]

Hi Krati team:

I see in IOTypeLongArray.set(), you update db first and then write
log. It looks like not a WAL. If you already update db, why still
need write log?

Thanks.

-Yuan

[Jingwei]

Hi Yuan,

The IOTypeLongArray is for experimental purpose and it uses IO page
cache for indexes.dat. There is no consistency guarantee. We have not
used it for production use at LinkedIn.

As you have observed that it updates the indexes.dat before writing
into redo. There is not appropriate. A proper sequence is accumulating
updates, writing into redo and then flushing accumulated updates to
indexes.dat. I never get to the point of accumulating updates.

Thanks.

Jingwei