Re: Parallel Seq Scan vs kernel read ahead

> It doesn't look like it's using table_block_parallelscan_nextpage() as
> a block allocator so it's not affected by the patch.  It has its own
> thing zs_parallelscan_nextrange(), which does
> pg_atomic_fetch_add_u64(&pzscan->pzs_allocatedtids,
> ZS_PARALLEL_CHUNK_SIZE), and that macro is 0x100000.

My apologies, I was too hasty. Indeed, you are correct. Zedstore's
unit of work is chunks of the logical zstid space. There is a
correlation between the zstid and blocks: zstids near each other are
likely to lie in the same block or in neighboring blocks. It would be
interesting to try something like this patch for Zedstore.

Regards,
Soumyadeep