Re: JSONB index not in use, but is TOAST the real cause of slow query?

On 5/28/22 12:38, Shaheed Haque wrote:
> Tom,
> 
> Thanks for the considered advice and insights. My takeaway is that
> based on what I've said,you are mostly unsurprised by the results I
> see. In the longer term, the number of rows will increase but I will
> have to ponder options for the immediate future. I'll have a play with
> the knobs you suggested and will report back with anything of note.
> 
> One last thought about TOAST. If the cost of the -> retrieving the
> data cannot be obviated, is there any way to tweak how that works?

See:

https://www.postgresql.org/docs/current/storage-toast.html

and from there:

https://www.postgresql.org/docs/current/sql-altertable.html

Search for SET STORAGE.

It might help with(from Tom Lane):

"Unfortunately the planner doesn't account
for detoasting costs when making such estimates, ..."

but probably not much with:

" ...because anything at all that you do with
that big JSONB column is going to be expensive.  (Another thing
that's been on the to-do list for awhile is enabling partial
retrieval of large JSONB values, but AFAIK that hasn't happened
yet either.)

> 
> Thanks, Shaheed
> 


-- 
Adrian Klaver
adrian.klaver@aklaver.com