Re: Is the PL/pgSQL refcursor useful in a modern three-tier app?

čt 16. 3. 2023 v 9:18 odesílatel Dominique Devienne <ddevienne(at)gmail(dot)com>
napsal:

> On Thu, Mar 16, 2023 at 6:48 AM Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at>
> wrote:
>
>> As we wrote, some of us think that cursors are useful, and we tried to
>> explain why we think that. If you don't think that cursors are useful,
>> don't use them. We are not out to convince you otherwise.
>>
>
> Perhaps OT (I only skimed this thread) but when I compared Cursors to
> regular Statements / Queries
> from a LIBPQ client application perspective, on the same "streamable"
> queries (i.e. w/o a sort), Cursor
> shined in terms of time-to-first-row, compared to waiting for the whole
> ResultSet, but getting the full result
> OTOH was 2x as long with Cursor, compared to the regular SELECT Statement.
>
> Thus in my mind, it really depends on what you value in a particular
> situation, latency or throughput. --DD
>
>
cursors are optimized for minimal cost of first row, queries are optimized
for minimal cost of last row

Regards

Pavel

> PS: In my testing, I used forward-only cursors
> PPS: I don't recall the ResultSet cardinality or byte size, nor the
> batching used with the Cursor.
>