Blocked sort-based indexing (BSBI)
- Accumulate records for each block
- sort
- create the posting lists
- write to disk.
- merge blocks into 1 sorted order.
def bsbi(docs)
n = 0
while not_proceessed(docs):
n = n + 1
block = parseNextBlock()
bsbi_invert(block)
write_block_to_disk(block, fn)
merge_blocks(f1, ..., fn, fmerged)