Re: Logical Replica ReorderBuffer Size Accounting Issues

> Do you have any sample data to confirm
> this? If you can't share sample data, can you let us know the average
> tuple size?
>

I suspect the writes are updates to jsonb columns. I can correlate bursts
of writes of this form to the memory spikes:
UPDATE suspect_table
SET jsonb_column = jsonb_column || $1,
updated_at = $2
WHERE ...

The update being added in $1 is typically a single new field. The jsonb
column is flat string key/value pairs, e.g. lots of {"key": "value", ...}.

The average size of the whole tuple in the suspect table is ~800 bytes
(based on 10000 random samples), of which the jsonb column is 80%.

I have been trying to break into a walsender to inspect some tuple bufs
directly and compare the ChangeSize vs GetTupleBuf size as you suggest, but
it's proving a little tricky - I'll let you know if I have any luck here.

Thanks,
- Alex.