On 6/20/23 12:02, nicolas paris wrote:
>...
>
> Definitely this makes sense to add the part_col in the join columns.
> Also it helps the planner to choose a better plan, since now it goes
> with per partition nested loop without having to trick the costs
> (either enable_hashjoin/random_page_cost),
> This is absolutely expected. If you partition by hash (id, part_key),
> you can't join on (id) and expect partitionwise join to work. To
> quote
> the enable_partitionwise_join documentation [1]:
>
> Enables or disables the query planner's use of partitionwise
> join,
> which allows a jo
On 6/19/23 17:45, nicolas paris wrote:
>> But you wrote that in both cases the query is:
>
> that was indeed yet another tipo, hope to do better in the future.
>
>
>> I'm willing to continue to investigate, but only if you prepare a
>> reproducer,
>
> Thanks for your starter script. Please
> But you wrote that in both cases the query is:
that was indeed yet another tipo, hope to do better in the future.
> I'm willing to continue to investigate, but only if you prepare a
> reproducer,
Thanks for your starter script. Please find attached 2 scripts which
now illustrates two trouble
On 6/19/23 14:20, nicolas paris wrote:
>> IMHO the thing that breaks it is the ORDER BY in the merge, which
>> likely
>> acts as an optimization fence and prevents all sorts of smart things
>> including the partitionwise join. I'd bet that if Nicolas replaces
>>
>> MERGE INTO "goliath" ca
>> US
> IMHO the thing that breaks it is the ORDER BY in the merge, which
> likely
> acts as an optimization fence and prevents all sorts of smart things
> including the partitionwise join. I'd bet that if Nicolas replaces
>
> MERGE INTO "goliath" ca
> USING (SELECT * FROM "david" ORDER BY "list_id"
On Mon, 2023-06-19 at 13:34 +0200, Tomas Vondra wrote:
>
>
> On 6/18/23 22:57, nicolas paris wrote:
> > > ...
> > > Well, I kinda doubt you have 17023331531230 rows (not even
> > > physically
> > > possible with 2TB disk), so that's immediately suspicious.
> >
> > Below is the full plan for the
On 6/19/23 09:46, Alvaro Herrera wrote:
> I came here to talk about partitionwise join, but then noticed you have
> already thought of that:
>
> On 2023-Jun-18, nicolas paris wrote:
>
>> Note that both plan acome from the same partitioned by hash table with
>> 100 parts, with a unique index on
On 6/18/23 22:57, nicolas paris wrote:
>> ...
>> Well, I kinda doubt you have 17023331531230 rows (not even physically
>> possible with 2TB disk), so that's immediately suspicious.
>
> Below is the full plan for the strategy 2.1 (Indeed the previous email
> plan was truncated and wrong, sorry f
I came here to talk about partitionwise join, but then noticed you have
already thought of that:
On 2023-Jun-18, nicolas paris wrote:
> Note that both plan acome from the same partitioned by hash table with
> 100 parts, with a unique index on the list_id + hash_key. For strategy
> 2.1, I turned o
> I assume 2TO is 2TB?
Yes. 2TB
> I don't understand why you're sharing just a part of the plan
As for the nested loop plan, what I shared is the full plan. Actually
it is repeated many times, since 2M batched by 500 rows. I add it
again:
Merge on goliath_23 ca (cost=2139.75..11077.17 rows=
On 6/17/23 23:42, nicolas paris wrote:
>>> My interpretation reading the query plan is: well sized small
>>> batches of upserts leverage the indexes while the regular join
>>> choose the sequential scan, including sorting and hashing which
>>> takes forever time and resources including disk.
>>
> > My interpretation reading the query plan is: well sized small
> > batches of upserts leverage the indexes while the regular join
> > choose the sequential scan, including sorting and hashing which
> > takes forever time and resources including disk.
>
> You may be right, but it's hard to tell
On 6/17/23 15:48, Nicolas Paris wrote:
> In my use case I have a 2billion / 1To table. I have daily data to upsert
> around 2milion, with say 50% inserts, based on the primary key in a fresh
> analyzed table.
>
> I have tested multiple strategies to merge the data, all based on first stage
> to
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