New feature request

[phuongph]

I think it will be very nice if indexd supports bulk input. Most of the regular use cases are good, each insertion takes roughly 25 milliseconds. I think if we insert 1000 entries at a time, it will take much less than 25ms x 1000 = 25s.

Two use cases will benefit significantly:

1. backup-indexd-populator takes 24-26 hours now to populate 1.8-1.9 million entries. It will take significant less time(hopefully 30-60 minutes)

2. signpost-2-indexd migration takes about 60-70 hours (depending on environment) to migrate about 3.5 million entries. It will take much less time (probably 60-90 minutes)

[zflamig]

Duplicate of #58