Maximum transaction size/splitting up large transactions?

[Zach Brown]

On Thu, Mar 27, 2025 at 09:33:30PM +0100, Valerie Aurora wrote:
> Hey ngneers,
> 
> I've implemented file data reads/writes, and I have this comment
> outside the main loop of per block reads/writes:
> 
> /* XXX break up into smaller transactions */
> 
> Is this something to leave for later, or is it worth discussing now?
> For file data, my ideal would be some way to check how much space I
> have left in the transaction before I add another block and its
> potential additional indirect blocks.

I imagine we should leave it for later, specifically for when the block
cache is able to track and send writes as transactions.  But it's always
nice to discuss to frame the problem :).

I think my initial bias is to try to not have code paths that are
managing transaction sizes that way.  Simply 'cause not doing it is less
code (and control flows that need to be (not) tested).

These client side transaction boundaries are just what are being
atomically dirtied.  They might well be being merged into larger
transactions that will eventually be sent over the wire. 

- z