On Wed, 26 May 2021 at 14:19, Andy Fan wrote:
> I just checked the latest code, looks like we didn't improve this situation
> except
> that we introduced a GUC to control it. Am I missing something? I don't
> have a
> suggestion though.
Various extra caching was done to help speed it up. We
On Fri, Mar 12, 2021 at 8:31 AM David Rowley wrote:
> Thanks for these suggestions.
>
> On Mon, 22 Feb 2021 at 14:21, Justin Pryzby wrote:
> >
> > On Tue, Feb 16, 2021 at 11:15:51PM +1300, David Rowley wrote:
> > > To summarise here, the planner performance gets a fair bit worse with
> > > the p
On Thu, 1 Apr 2021 at 23:41, houzj.f...@fujitsu.com
wrote:
>
> > I've attached the updated patch. I'll let the CFbot grab this to ensure
> > it's
> > happy with it before I go looking to push it again.
>
> Hi,
>
> I took a look into the patch and noticed some minor things.
>
> 1.
> +
> I've attached the updated patch. I'll let the CFbot grab this to ensure it's
> happy with it before I go looking to push it again.
Hi,
I took a look into the patch and noticed some minor things.
1.
+ case T_ResultCache:
+ ptype = "ResultCache";
+
On Wed, 31 Mar 2021 at 05:34, Zhihong Yu wrote:
>
> Hi,
> In paraminfo_get_equal_hashops(),
>
> + /* Reject if there are any volatile functions */
> + if (contain_volatile_functions(expr))
> + {
>
> You can move the above code to just ahead of:
>
> + if (IsA(expr, Var))
> +
Hi,
In paraminfo_get_equal_hashops(),
+ /* Reject if there are any volatile functions */
+ if (contain_volatile_functions(expr))
+ {
You can move the above code to just ahead of:
+ if (IsA(expr, Var))
+ var_relids = bms_make_singleton(((Var *) expr)->varno);
Th
Hi,
For show_resultcache_info()
+ if (rcstate->shared_info != NULL)
+ {
The negated condition can be used with a return. This way, the loop can be
unindented.
+ * ResultCache nodes are intended to sit above a parameterized node in the
+ * plan tree in order to cache results from them.
Since
On Fri, 12 Mar 2021 at 14:59, Tom Lane wrote:
>
> David Rowley writes:
> > The 0001 patch adds a has_volatile bool field to RestrictInfo and sets
> > it when building the RestrictInfo.
>
> I'm -1 on doing it exactly that way, because you're expending
> the cost of those lookups without certainty
David Rowley writes:
> On Tue, 23 Feb 2021 at 18:43, Tom Lane wrote:
>> I doubt it's that bad. We could cache such info in RestrictInfo
>> for quals, or PathTarget for tlists, without much new notational
>> overhead. That doesn't cover everything the planner deals with
>> of course, but it woul
On Tue, 23 Feb 2021 at 14:22, Andy Fan wrote:
>
> On Mon, Feb 22, 2021 at 9:21 AM Justin Pryzby wrote:
>> - Maybe this should be integrated into nestloop rather than being a separate
>>plan node. That means that it could be dynamically enabled during
>>execution, maybe after a few loops
Thanks for these suggestions.
On Mon, 22 Feb 2021 at 14:21, Justin Pryzby wrote:
>
> On Tue, Feb 16, 2021 at 11:15:51PM +1300, David Rowley wrote:
> > To summarise here, the planner performance gets a fair bit worse with
> > the patched code. With master, summing the average planning time over
>
On Tue, Feb 23, 2021 at 10:44 AM Tom Lane wrote:
> Andres Freund writes:
> > We could add a wrapper node around "planner expressions" that stores
> > metadata about them during planning, without those properties leaking
> > over expressions used at other times. E.g. having
> > preprocess_express
Andres Freund writes:
> We could add a wrapper node around "planner expressions" that stores
> metadata about them during planning, without those properties leaking
> over expressions used at other times. E.g. having
> preprocess_expression() return a PlannerExpr that that points to the
> expressi
Hi,
On 2021-02-22 20:51:17 -0500, Tom Lane wrote:
> Andres Freund writes:
> > Except for the annoying issue that that we pervasively use Lists as
> > expressions, I'd argue that we should actually cache "subtree
> > volatility" in Expr nodes, similar to the way we use OpExpr.opfuncid
> > etc. Tha
Andres Freund writes:
> Except for the annoying issue that that we pervasively use Lists as
> expressions, I'd argue that we should actually cache "subtree
> volatility" in Expr nodes, similar to the way we use OpExpr.opfuncid
> etc. That'd allow us to make contain_volatile_functions() very cheap
Hi,
On 2021-02-16 23:15:51 +1300, David Rowley wrote:
> There might be gains to be had by checking the parse once rather than
> having to call contains_volatile_functions in the various places we do
> call it. I think both the parallel safety and volatile checks could
> then be done in the same tr
On Mon, Feb 22, 2021 at 9:21 AM Justin Pryzby wrote:
> On Tue, Feb 16, 2021 at 11:15:51PM +1300, David Rowley wrote:
> > To summarise here, the planner performance gets a fair bit worse with
> > the patched code. With master, summing the average planning time over
> > each of the queries resulted
On Tue, Feb 16, 2021 at 11:15:51PM +1300, David Rowley wrote:
> To summarise here, the planner performance gets a fair bit worse with
> the patched code. With master, summing the average planning time over
> each of the queries resulted in a total planning time of 765.7 ms.
> After patching, that w
On Tue, Feb 16, 2021 at 6:16 PM David Rowley wrote:
> On Wed, 3 Feb 2021 at 19:51, David Rowley wrote:
> > I've attached a spreadsheet with the results of each of the tests.
> >
> > The attached file v13_costing_hacks.patch.txt is the quick and dirty
> > patch I put together to run test 5.
>
> I
Thanks for having a look at this.
I've taken most of your suggestions. The things quoted below are just
the ones I didn't agree with or didn't understand.
On Thu, 28 Jan 2021 at 18:43, Justin Pryzby wrote:
>
> On Tue, Dec 08, 2020 at 08:15:52PM +1300, David Rowley wrote:
> > +typedef struct Esti
Thanks a lot for testing this patch. It's good to see it run through a
benchmark that exercises quite a few join problems.
On Fri, 11 Dec 2020 at 05:44, Konstantin Knizhnik
wrote:
> For most queries performance is the same, some queries are executed
> faster but
> one query is 150 times slower:
>
On Tue, 8 Dec 2020 at 20:15, David Rowley wrote:
> I've attached another patchset that addresses some comments left by
> Zhihong Yu over on [1]. The version number got bumped to v12 instead
> of v11 as I still have a copy of the other version of the patch which
> I made some changes to and intern
>> just removing the logic that has the
soft upper limit and just have it do cache evictions after each
allocation after the cache first fills
Yeah - having one fewer limit would simplify the code.
Cheers
On Mon, Dec 7, 2020 at 5:27 PM David Rowley wrote:
> On Mon, 7 Dec 2020 at 14:25, Zhihon
On Mon, 7 Dec 2020 at 14:25, Zhihong Yu wrote:
>
> > + /* Make a guess at a good size when we're not given a valid size. */
> > + if (size == 0)
> > + size = 1024;
> >
> > Should the default size be logged ?
>
> > I'm not too sure if I know what you mean here. Should it be a power of
> >
> + /* Make a guess at a good size when we're not given a valid size. */
> + if (size == 0)
> + size = 1024;
>
> Should the default size be logged ?
> I'm not too sure if I know what you mean here. Should it be a power of
> 2? It is. Or do you mean I shouldn't use a magic number?
Using
On Sat, 5 Dec 2020 at 16:51, Zhihong Yu wrote:
>
> There are two blocks with almost identical code (second occurrence in
> cache_store_tuple):
>
> + if (rcstate->mem_used > rcstate->mem_upperlimit)
> + {
> It would be nice if the code can be extracted to a method and shared.
It's true, they'
Thanks for having a look at this.
On Sat, 5 Dec 2020 at 14:08, Zhihong Yu wrote:
> +#define SH_EQUAL(tb, a, b) ResultCacheHash_equal(tb, a, b) == 0
>
> I think it would be safer if the comparison is enclosed in parentheses (in
> case the macro appears in composite condition).
That seems fair.
On Sun, 6 Dec 2020 at 03:52, Andy Fan wrote:
>
> On Fri, Dec 4, 2020 at 10:41 PM David Rowley wrote:
>>
>> I also
>> noticed that the code I'd written to build the cache lookup expression
>> included a step to deform the outer tuple. This was unnecessary and
>> slowed down the expression evaluati
Thanks for this review. I somehow missed addressing what's mentioned
here for the v10 patch. Comments below.
On Mon, 23 Nov 2020 at 02:21, Andy Fan wrote:
> 1. modified src/include/utils/selfuncs.h
> @@ -70,9 +70,9 @@
> * callers to provide further details about some assumptions which were m
Thanks for working on the new version.
On Fri, Dec 4, 2020 at 10:41 PM David Rowley wrote:
>
> I also
> noticed that the code I'd written to build the cache lookup expression
> included a step to deform the outer tuple. This was unnecessary and
> slowed down the expression evaluation.
>
>
I thou
There are two blocks with almost identical code (second occurrence in
cache_store_tuple):
+ if (rcstate->mem_used > rcstate->mem_upperlimit)
+ {
It would be nice if the code can be extracted to a method and shared.
node->rc_status = RC_END_OF_SCAN;
ret
Hi, David:
For nodeResultCache.c :
+#define SH_EQUAL(tb, a, b) ResultCacheHash_equal(tb, a, b) == 0
I think it would be safer if the comparison is enclosed in parentheses (in
case the macro appears in composite condition).
+ResultCacheHash_equal(struct resultcache_hash *tb, const ResultCacheKey
On Fri, Nov 27, 2020 at 8:10 AM David Rowley wrote:
> Thanks for having another look at this.
>
> > On Sun, Nov 22, 2020 at 9:21 PM Andy Fan
> wrote:
> > add 2 more comments.
> >
> > 1. I'd suggest adding Assert(false); in RC_END_OF_SCAN case to make the
> error clearer.
> >
> > case RC_END_OF_
Thanks for having another look at this.
> On Sun, Nov 22, 2020 at 9:21 PM Andy Fan wrote:
> add 2 more comments.
>
> 1. I'd suggest adding Assert(false); in RC_END_OF_SCAN case to make the
> error clearer.
>
> case RC_END_OF_SCAN:
> /*
> * We've already returned NULL for this scan, but just in
On Sun, Nov 22, 2020 at 9:21 PM Andy Fan wrote:
> Hi David:
>
> I did a review on the v8, it looks great to me. Here are some tiny
> things noted,
> just FYI.
>
> 1. modified src/include/utils/selfuncs.h
> @@ -70,9 +70,9 @@
> * callers to provide further details about some assumptions whic
Hi David:
I did a review on the v8, it looks great to me. Here are some tiny things
noted,
just FYI.
1. modified src/include/utils/selfuncs.h
@@ -70,9 +70,9 @@
* callers to provide further details about some assumptions which were
made
* during the estimation.
*/
-#define SELFLAG_USED_
On Tue, 10 Nov 2020 at 12:55, David Rowley wrote:
>
> On Tue, 10 Nov 2020 at 12:49, Tom Lane wrote:
> >
> > Alvaro Herrera writes:
> > > Are you taking into account the possibility that generated machine code
> > > is a small percent slower out of mere bad luck? I remember someone
> > > suggest
On Tue, 10 Nov 2020 at 15:38, Andy Fan wrote:
> While I have interest about what caused the tiny difference, I admit that
> what direction
> this patch should go is more important. Not sure if anyone is convinced that
> v8 and v9 have a similar performance. The current data show it is similar.
On Tue, Nov 10, 2020 at 7:55 AM David Rowley wrote:
> On Tue, 10 Nov 2020 at 12:49, Tom Lane wrote:
> >
> > Alvaro Herrera writes:
> > > Are you taking into account the possibility that generated machine code
> > > is a small percent slower out of mere bad luck? I remember someone
> > > sugges
On Mon, Nov 9, 2020 at 3:49 PM Tom Lane wrote:
> Alvaro Herrera writes:
> > Are you taking into account the possibility that generated machine code
> > is a small percent slower out of mere bad luck? I remember someone
> > suggesting that they can make code 2% faster or so by inserting random
>
On Tue, 10 Nov 2020 at 12:49, Tom Lane wrote:
>
> Alvaro Herrera writes:
> > Are you taking into account the possibility that generated machine code
> > is a small percent slower out of mere bad luck? I remember someone
> > suggesting that they can make code 2% faster or so by inserting random
>
Alvaro Herrera writes:
> Are you taking into account the possibility that generated machine code
> is a small percent slower out of mere bad luck? I remember someone
> suggesting that they can make code 2% faster or so by inserting random
> no-op instructions in the binary, or something like that
On 2020-Nov-10, David Rowley wrote:
> On Mon, 9 Nov 2020 at 16:29, Andy Fan wrote:
> > However I believe v9
> > should be no worse than v8 all the time, Is there any theory to explain
> > your result?
>
> Nothing jumps out at me from looking at profiles. The only thing I
> noticed was the t
On Mon, 9 Nov 2020 at 16:29, Andy Fan wrote:
> I think either version is OK for me and I like this patch overall.
That's good to know. Thanks.
> However I believe v9
> should be no worse than v8 all the time, Is there any theory to explain
> your result?
Nothing jumps out at me from looking a
On Mon, Nov 9, 2020 at 10:07 AM David Rowley wrote:
> On Mon, 9 Nov 2020 at 03:52, Andy Fan wrote:
> > then I did a perf on the 2 version, Is it possible that you called
> tts_minimal_clear twice in
> > the v9 version? Both ExecClearTuple and ExecStoreMinimalTuple called
> tts_minimal_clear
>
On Mon, 9 Nov 2020 at 03:52, Andy Fan wrote:
> then I did a perf on the 2 version, Is it possible that you called
> tts_minimal_clear twice in
> the v9 version? Both ExecClearTuple and ExecStoreMinimalTuple called
> tts_minimal_clear
> on the same slot.
>
> With the following changes:
Thank
On Mon, Nov 2, 2020 at 3:44 PM David Rowley wrote:
> On Tue, 20 Oct 2020 at 22:30, David Rowley wrote:
> >
> > So far benchmarking shows there's still a regression from the v8
> > version of the patch. This is using count(*). An earlier test [1] did
> > show speedups when we needed to deform tup
On Fri, Nov 6, 2020 at 6:13 AM David Rowley wrote:
> On Mon, 2 Nov 2020 at 20:43, David Rowley wrote:
> >
> > On Tue, 20 Oct 2020 at 22:30, David Rowley wrote:
> > I did some further tests this time with some tuple deforming. Again,
> > it does seem that v9 is slower than v8.
> >
> > Graphs at
On Mon, 2 Nov 2020 at 20:43, David Rowley wrote:
>
> On Tue, 20 Oct 2020 at 22:30, David Rowley wrote:
> I did some further tests this time with some tuple deforming. Again,
> it does seem that v9 is slower than v8.
>
> Graphs attached
>
> Looking at profiles, I don't really see any obvious reas
On 2020-Sep-02, David Rowley wrote:
> v7 (Separate Result Cache node)
> Query 1:
> Execution Time: 894.003 ms
>
> Query 2:
> Execution Time: 854.950 ms
> v7 + hacks_V3 (caching done in Nested Loop)
> Query 1:
> Execution Time: 770.470 ms
>
> Query 2
> Execution Time: 779.181 ms
Wow, this is
On Sat, 29 Aug 2020 at 02:54, David Rowley wrote:
>
> On Wed, 26 Aug 2020 at 03:52, Andres Freund wrote:
> > There'll be a significant reduction in increase in performance.
>
> So I did a very rough-cut change to the patch to have the caching be
> part of Nested Loop. It can be applied on top of
Thanks for chipping in here.
On Mon, 31 Aug 2020 at 17:57, Thomas Munro wrote:
> I wonder what it would take to overcome the overheads of the separate
> Result Cache node, with techniques to step out of the way or something
> like that.
So far it looks like there are more overheads to having the
On Sat, Aug 29, 2020 at 3:33 AM Robert Haas wrote:
> I think David's points elsewhere on the thread about ProjectSet and
> Materialize nodes are interesting.
Indeed, I'm now finding it very difficult to look past the similarity with:
postgres=# explain select count(*) from t t1 cross join t t2;
On Wed, Aug 19, 2020 at 6:58 PM Alvaro Herrera wrote:
> On 2020-Aug-19, David Rowley wrote:
> > Andres' suggestion:
> > regression=# explain (analyze, costs off, timing off, summary off)
> > select count(*) from tenk1 t1 inner join tenk1 t2 on
> > t1.twenty=t2.unique1;
> >
On Sat, 29 Aug 2020 at 02:54, David Rowley wrote:
> I'm open to ideas to make the comparison fairer.
While on that, it's not just queries that don't require the cached
tuple to be deformed that are slower. Here's a couple of example that
do requite both patches to deform the cached tuple:
Some
On Wed, 26 Aug 2020 at 03:52, Andres Freund wrote:
>
> On 2020-08-25 20:48:37 +1200, David Rowley wrote:
> > However, given the correct planner choice, there will never be
> > a gross slowdown due to having the extra node.
>
> There'll be a significant reduction in increase in performance.
So I d
On Wed, Aug 26, 2020 at 8:14 AM David Rowley wrote:
> On Wed, 26 Aug 2020 at 05:18, Andy Fan wrote:
> >
> >
> > On Tue, Aug 25, 2020 at 11:53 PM Andres Freund
> wrote:
> >>
> >> On 2020-08-25 20:48:37 +1200, David Rowley wrote:
> >> > Also, just in case anyone is misunderstanding this Andres' a
On Wed, 26 Aug 2020 at 05:18, Andy Fan wrote:
>
>
> On Tue, Aug 25, 2020 at 11:53 PM Andres Freund wrote:
>>
>> On 2020-08-25 20:48:37 +1200, David Rowley wrote:
>> > Also, just in case anyone is misunderstanding this Andres' argument.
>> > It's entirely based on the performance impact of having
On Tue, Aug 25, 2020 at 11:53 PM Andres Freund wrote:
> Hi,
>
> On 2020-08-25 20:48:37 +1200, David Rowley wrote:
> > On Tue, 25 Aug 2020 at 08:26, Andres Freund wrote:
> > > While I'm against introducing a separate node for the caching, I'm
> *not*
> > > against displaying a different node type
On Tue, Aug 25, 2020 at 11:53 PM Andres Freund wrote:
> Hi,
>
> On 2020-08-25 20:48:37 +1200, David Rowley wrote:
> > On Tue, 25 Aug 2020 at 08:26, Andres Freund wrote:
> > > While I'm against introducing a separate node for the caching, I'm
> *not*
> > > against displaying a different node type
Hi,
On 2020-08-25 20:48:37 +1200, David Rowley wrote:
> On Tue, 25 Aug 2020 at 08:26, Andres Freund wrote:
> > While I'm against introducing a separate node for the caching, I'm *not*
> > against displaying a different node type when caching is
> > present. E.g. it'd be perfectly reasonable from
On 25/08/2020 20:48, David Rowley wrote:
On Tue, 25 Aug 2020 at 08:26, Andres Freund wrote:
While I'm against introducing a separate node for the caching, I'm *not*
against displaying a different node type when caching is
present. E.g. it'd be perfectly reasonable from my POV to have a 'Cached
On Tue, 25 Aug 2020 at 08:26, Andres Freund wrote:
> While I'm against introducing a separate node for the caching, I'm *not*
> against displaying a different node type when caching is
> present. E.g. it'd be perfectly reasonable from my POV to have a 'Cached
> Nested Loop' join and a plain 'Neste
Hi,
On 2020-08-19 18:58:11 -0400, Alvaro Herrera wrote:
> On 2020-Aug-19, David Rowley wrote:
>
> > Andres' suggestion:
> >
> > regression=# explain (analyze, costs off, timing off, summary off)
> > select count(*) from tenk1 t1 inner join tenk1 t2 on
> > t1.twenty=t2.unique1;
> >
čt 20. 8. 2020 v 0:04 odesílatel David Rowley napsal:
> On Wed, 19 Aug 2020 at 16:18, Pavel Stehule
> wrote:
> >
> >
> >
> > st 19. 8. 2020 v 5:48 odesílatel David Rowley
> napsal:
> >> Current method:
> >>
> >> regression=# explain (analyze, costs off, timing off, summary off)
> >> select twen
On Thu, 20 Aug 2020 at 10:58, Alvaro Herrera wrote:
> On the performance aspect, I wonder what the overhead is, particularly
> considering Tom's point of making these nodes more expensive for cases
> with no caching.
It's likely small. I've not written any code but only thought about it
and I thi
On 2020-Aug-19, David Rowley wrote:
> Andres' suggestion:
>
> regression=# explain (analyze, costs off, timing off, summary off)
> select count(*) from tenk1 t1 inner join tenk1 t2 on
> t1.twenty=t2.unique1;
> QUERY PLAN
>
On Wed, 19 Aug 2020 at 16:18, Pavel Stehule wrote:
>
>
>
> st 19. 8. 2020 v 5:48 odesílatel David Rowley napsal:
>> Current method:
>>
>> regression=# explain (analyze, costs off, timing off, summary off)
>> select twenty, (select count(*) from tenk1 t2 where t1.twenty =
>> t2.twenty) from tenk1
On Wed, 19 Aug 2020 at 16:23, Tom Lane wrote:
>
> David Rowley writes:
> > I don't object to making the change. I just object to making it only
> > to put it back again later when someone else speaks up that they'd
> > prefer to keep nodes modular and not overload them in obscure ways.
>
> > So o
David Rowley writes:
> I don't object to making the change. I just object to making it only
> to put it back again later when someone else speaks up that they'd
> prefer to keep nodes modular and not overload them in obscure ways.
> So other input is welcome. Is it too weird to overload SubPlan
st 19. 8. 2020 v 5:48 odesílatel David Rowley napsal:
> On Tue, 18 Aug 2020 at 21:42, David Rowley wrote:
> >
> > On Tue, 11 Aug 2020 at 17:44, Andres Freund wrote:
> > >
> > > Hi,
> > >
> > > On 2020-08-11 17:23:42 +1200, David Rowley wrote:
> > > > On Tue, 11 Aug 2020 at 12:21, Andres Freund
On Tue, 18 Aug 2020 at 21:42, David Rowley wrote:
>
> On Tue, 11 Aug 2020 at 17:44, Andres Freund wrote:
> >
> > Hi,
> >
> > On 2020-08-11 17:23:42 +1200, David Rowley wrote:
> > > On Tue, 11 Aug 2020 at 12:21, Andres Freund wrote:
> > > >
> > > > On 2020-07-09 10:25:14 +1200, David Rowley wrote
On Tue, 11 Aug 2020 at 17:44, Andres Freund wrote:
>
> Hi,
>
> On 2020-08-11 17:23:42 +1200, David Rowley wrote:
> > On Tue, 11 Aug 2020 at 12:21, Andres Freund wrote:
> > >
> > > On 2020-07-09 10:25:14 +1200, David Rowley wrote:
> > > > On Thu, 9 Jul 2020 at 04:53, Andres Freund wrote:
> > > >
Hi,
On 2020-08-11 17:23:42 +1200, David Rowley wrote:
> On Tue, 11 Aug 2020 at 12:21, Andres Freund wrote:
> >
> > On 2020-07-09 10:25:14 +1200, David Rowley wrote:
> > > On Thu, 9 Jul 2020 at 04:53, Andres Freund wrote:
> > > > I'm not convinced it's a good idea to introduce a separate executor
On Tue, 11 Aug 2020 at 12:21, Andres Freund wrote:
>
> On 2020-07-09 10:25:14 +1200, David Rowley wrote:
> > On Thu, 9 Jul 2020 at 04:53, Andres Freund wrote:
> > > I'm not convinced it's a good idea to introduce a separate executor node
> > > for this. There's a fair bit of overhead in them, and
Hi,
On 2020-07-09 10:25:14 +1200, David Rowley wrote:
> On Thu, 9 Jul 2020 at 04:53, Andres Freund wrote:
> >
> > On 2020-05-20 23:44:27 +1200, David Rowley wrote:
> > > I've attached a patch which implements this. The new node type is
> > > called "Result Cache". I'm not particularly wedded to
On Thu, 6 Aug 2020 at 05:44, Andres Freund wrote:
> > Andres, or anyone, any objections to me pushing 0002?
>
> I think it'd be good to add a warning that, unless one is very careful,
> no other hashtable modifications are allowed between lookup and
> modification. E.g. something like
> a = foobar
On Thu, 6 Aug 2020 at 08:13, Robert Haas wrote:
>
> This is cool work; I am going to bikeshed on the name for a minute. I
> don't think Result Cache is terrible, but I have two observations:
Thanks
> 1. It might invite confusion with a feature of some other database
> systems where they cache th
On Wed, May 20, 2020 at 4:44 AM David Rowley wrote:
> Does it seem like something we might want for PG14?
Minor terminology issue: "Hybrid Hash Join" is a specific hash join
algorithm which is unrelated to what you propose to do here. I hope
that confusion can be avoided, possibly by not using th
On Wed, May 20, 2020 at 7:44 AM David Rowley wrote:
> I've attached a patch which implements this. The new node type is
> called "Result Cache". I'm not particularly wedded to keeping that
> name, but if I change it, I only want to do it once. I've got a few
> other names I mind, but I don't fee
Hi,
On 2020-08-04 10:05:25 +1200, David Rowley wrote:
> I'd like to push the 0002 patch quite soon as I think it's an
> improvement to simplehash.h regardless of if we get Result Cache. It
> reuses the SH_LOOKUP function for deletes. Also, if we ever get around
> to giving up performing a lookup
On Thu, 9 Jul 2020 at 04:53, Andres Freund wrote:
>
> On 2020-05-20 23:44:27 +1200, David Rowley wrote:
> > I've attached a patch which implements this. The new node type is
> > called "Result Cache". I'm not particularly wedded to keeping that
> > name, but if I change it, I only want to do it
Hi,
On 2020-05-20 23:44:27 +1200, David Rowley wrote:
> I've attached a patch which implements this. The new node type is
> called "Result Cache". I'm not particularly wedded to keeping that
> name, but if I change it, I only want to do it once. I've got a few
> other names I mind, but I don't f
On Fri, 12 Jun 2020 at 16:10, Andy Fan wrote:
> I first tried to see if we can have a row estimation before the subplan
> is created and it looks very complex. The subplan was created during
> preprocess_qual_conditions, at that time, we even didn't create the base
> RelOptInfo , to say nothing o
On Wed, Jun 3, 2020 at 10:36 AM Andy Fan wrote:
>
>> Thanks for running those tests. I had a quick look at the results and
>> I think to say that all 4 are better is not quite right. One is
>> actually a tiny bit slower and one is only faster due to a plan
>> change.
>>
>>
> Yes.. Thanks for po
>
>
> Thanks for running those tests. I had a quick look at the results and
> I think to say that all 4 are better is not quite right. One is
> actually a tiny bit slower and one is only faster due to a plan
> change.
>
>
Yes.. Thanks for pointing it out.
> Q18 uses a result cache for 2 x neste
On Tue, 2 Jun 2020 at 21:05, Andy Fan wrote:
> Today I tested the correctness & performance of this patch based on TPC-H
> workload, the environment is setup based on [1]. Correctness is tested by
> storing the result into another table when this feature is not introduced and
> then enable this fe
On Fri, 22 May 2020 at 12:12, Andy Fan wrote:
> Actually I am not sure about what does the "parameterized sub plan" mean (I
> treat is a SubPlan Node), so please correct me if I misunderstand you:)
> Because
> the inner plan in nest loop not a SubPlan node actually. so if bind the
> facility to
> My question is whether it should be added as an optional facility of a
> parameterised sub plan, rather than an always-needed full-strength node.
> That way the choice of whether to use it can happen at execution time once
> we notice that we've been called too many times.
>
>
Actually I am not
On Thu, 21 May 2020 at 00:56, Simon Riggs wrote:
> I thought the main reason to do this was the case when the nested loop
> subplan was significantly underestimated and we realize during execution that
> we should have built a hash table. So including this based on cost alone
> seems to miss a
On Wed, 20 May 2020 at 12:44, David Rowley wrote:
> Hackers,
>
> Over on [1], Heikki mentioned about the usefulness of caching results
> from parameterized subplans so that they could be used again for
> subsequent scans which have the same parameters as a previous scan.
> On [2], I mentioned tha
Hackers,
Over on [1], Heikki mentioned about the usefulness of caching results
from parameterized subplans so that they could be used again for
subsequent scans which have the same parameters as a previous scan.
On [2], I mentioned that parameterized nested loop joins could see
similar gains with
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