Hi, hackers!
I want to propose improvement of GiST page layout.
GiST is optimized to reduce disk operations on search queries, for
example, windows search queries in case of R-tree.
I expect that more complicated page layout will help to tradeoff some
of CPU efficiency for disk efficiency.
GiST
n, Octonica & Ural Federal University.
2016-08-16 20:23 GMT+05:00 Anastasia Lubennikova :
> 09.08.2016 19:45, Andrew Borodin:
>>
>> Here is new version of the patch, now it includes recommendations from
>> Anastasia Lubennikova.
>>
>>
>> I've invest
Hi, hackers!
Some time ago I put a patch to commitfest that optimizes slightly GiST
inserts and updates. It's effect in general is quite modest (15% perf
improved), but for sorted data inserts are 3 times quicker. This
effect I attribute to mitigation of deficiencies of old split
algorithm.
Alexa
Hi hackers!
Here is the new patch version.
With the help of Mikhail Bakhterev I've optimized subroutines of the
penalty function. Index build time now is roughly equivalent to build
time before patch (test attached to thread start).
Time of SELECT statement execution is reduced by 40%.
Changes in
Thank you for your coments, Tom.
> Modern compilers are generally able to make their own decisions about it, and
> trying to put your thumb on the scales this heavily is not likely to improve
> the code.
Well, I have tested that combination of "static inline" affets
performance of index build on
Here is new version of the patch.
Now function pack_float is commented better.
All inline keywords are removed. I haven't found any performance loss for that.
Remove of static's showed 1%-7% performance loss in SELECT computation
(3 test runs), so I left statics where they are.
Actually, to avoid
Hi Heikki!
Thank you for reviewing the code, it's always inspiring when a work is
noted (:
>Looking at the code, by "margin", you mean the sum of all "edges", i.e. of
each dimension, of the cube.
Indeed. As far as I remember, this is a terminology of old R*-tree paper.
Now they use the word "perim
Oh, sorry, made one more attemp and now I see your algorithm differently.
So you propose to use oE and oV as a markers of borders for what I call Realm.
But there may be very little significant bits in one of this ranges.
pg_sphere and PostGiS extensions tried to use 1 as a marker, with
alike form
Well, arithmetics is too fragile.
This version of float packing with arithmetical packaging
static float
pack_float(float actualValue, int realm)
{
double max,min;
max = FLT_MAX / ( 8 >> realm );
min = FLT_MAX / ( 16 >> realm );
if( realm == 0 )
min = 0;
/* squeeze the actual value between min and
>autoconf check for IEEE 754 floats
Autoconf man says folowing:
>it is safe to assume IEEE-754 in most portable code these days
https://www.gnu.org/software/autoconf/manual/autoconf.html#Floating-Point-Portability
> A union might be more readable
Here is union version of the patch. It's slower 10%
>BTW, would someone explain to me why using a float here will not fail
>catastrophically for inputs outside the range of float?
Indeed, it will. And that's one of the reason I'm considering
advancing GiST API instead of advancing extensions.
It won't crash, but will produce terrible index, not s
>Personally I wouldn't be very happy about an IEEE754 assumption.
Ok, so let's avoid autoconf man. There is no real explanations of the
ground for this assumption, just a reference to paper of David
Goldberg (and there is no metion about IEEE754 is absoulte
everywhere). BTW, may be we can ask David
Hi hackers!
Here is gist cube penaly patch v5.
Changes:
1. union version of pack_float() is used, without warings and with
minimum asm commands emitted
2. test for __STDC_IEC_559__ is added, this is a standard way of C99
to determine float compliance with IEEE754. ANSI-only compiler+libs,
along wi
Here is v6 of cube penalty patch.
There was a warning about unused edge function under systems without
__STDC_IEC_559__ defined, this patch fixes it.
Regards, Andrey Borodin.
diff --git a/contrib/cube/cube.c b/contrib/cube/cube.c
index 3feddef..ad868ac 100644
--- a/contrib/cube/cube.c
+++ b/contr
Hi hackers!
Currently GiST treats NaN penalty as zero penalty, in terms of
generalized tree this means "perfect fit". I think that this situation
should be considered "worst fit" instead.
Here is a patch to highlight place in the code.
I could not construct test to generate bad tree, which would b
> Certainly, "NaN means infinity", as your patch proposes, has no more basis to
> it than "NaN means zero".
You are absolutley right. Now I see that best interpretation is "NaN
means NaN". Seems like we need only drop a check. Nodes with NaN
penalties will be considered even worser than those with
Hi Heikki!
> Got a link for a description of the RR*-tree? Would be good to reference it
> in the patch comments, too.
Well, as for now, the best way to reach the paper is
DOI 10.1145/1559845.1559929
http://sci-hub.cc/
Authors in conversations clearly stated that they endorse (not sure in
correct
> This thread has basically died, so marking as returned with feedback.
Well, not exactly died, but it's kind of in blind lead.
I'll summarize a bit for future references:
1. cube extension for indexing lowered dimensionality data (2d in 3d)
is broken. Queries effectively will degrade to full inde
Hi hackers!
Here is prototype of procrastinating GiST. Or lazy GiST. Or buffered GiST.
Indeed, there is nothing fractal about it.
The concept is leaf tuples stall on internal pages. From time to time they
are pushed down in batches. This code is far from perfect, I've coded this
only for the rese
Hi!
It's great that you are interested in PostgreSQL!
I'll answer the question on the matter of GSoC project proposed by me.
I hope someone else will handle questions on your primary objective.
2017-03-03 4:15 GMT+05:00 João Miguel Afonso :
> My second choice would be the "Sorting algorithms be
Hi, Kirill!
2017-03-06 12:41 GMT+05:00 Кирилл Бороздин :
> My name is Kirill Borozdin. I am a student of Ural Federal University from
> Yekaterinburg, Russia.
That's fine. I'm the associate professor at Ural Federal University.
But not in your institution, though.
> I understand that this task wi
2017-03-16 21:27 GMT+05:00 David Steele :
> This patch applies cleanly and compiles at cccbdde.
>
> Jeff, any thoughts on Andrew's responses?
Hi, David!
I've got some updates on the matter of this patch, since the
understanding of the B-tree bothered me much.
Currently, I'm at PgConf.Russia, wher
2017-03-16 23:55 GMT+05:00 Peter Geoghegan :
> On Thu, Mar 16, 2017 at 11:53 AM, Andrew Borodin wrote:
>> 2. Thus, L&S fully concurrent vacuum is possible, indeed, and
>> furthermore Theodor suggested that I should implement not only page
>> eviction, but also pag
Hi, Teodor!
2017-03-21 20:32 GMT+05:00 Teodor Sigaev :
> I had a look on patch
That's great, thanks!
>
> /*
> * All subtree is empty - just return TRUE to indicate that parent
> must
> * do a cleanup. Unless we are ROOT an there is way to go upper.
> */
>
>
2017-03-22 22:48 GMT+05:00 Teodor Sigaev :
> hasEmptyChild? and hasNonEmptyChild (BTW, isAnyNonempy has missed 't')
Yes, I think this naming is good. It's clear what's in common in these
flags and what's different.
> And if the whole posting tree is empty,then we could mark root page as leaf
> an
Hello, hackers!
==Spatial joins==
Scientific papers from the dawn of R-trees and multidimensional
indexes feature a lot of algorithms for spatial joins.
I.e. you have two sets of geometries s1 and s2, you need to produce
all colliding pairs (p1,p2) where p1 in s1 and p2 in s2. For 2 R-trees
of equ
2017-04-10 20:38 GMT+05:00 Robert Haas :
> On Mon, Apr 10, 2017 at 7:53 AM, Andrew Borodin wrote:
>> I think this idea is somewhat related to this patch [2], but as for
>> now cannot describe how exactly GiST merge and Range Merge features
>> relate.
>
> It also seem
2017-04-11 14:17 GMT+05:00 Alexander Korotkov :
> FYI, I've implemented this algorithm for pgsphere. See following branch.
> https://github.com/akorotkov/pgsphere/tree/experimental
> It's implemented as crossmatch() function which takes as arguments names of
> two indexes over spoint and maximum d
2017-04-13 7:01 GMT+05:00 Jeff Davis :
> On Tue, Apr 11, 2017 at 8:35 AM, Alexander Korotkov
> wrote:
>> On Tue, Apr 11, 2017 at 5:46 PM, Jeff Davis wrote:
>>> Do you have a sense of how this might compare with range merge join?
>>
>>
>> If you have GiST indexes over ranges for both sides of join
2017-04-13 11:30 GMT+05:00 Jeff Davis :
> I don't quite follow. I don't think any of these proposals uses btree,
> right? Range merge join doesn't need any index, your proposal uses
> gist, and PgSphere's crossmatch uses gist.
Merge join will use presorted data, B-tree provides sorted data.
Merge
2017-06-16 17:06 GMT+03:00 Tom Lane :
> Yuan Dong writes:
>> ·¢¼þÈË: Andrew Borodin
>>> I think there is one more aspect of development: backward
>>> compatibility: it's impossible to update all existing extensions. This
>>> is not that major feature to
Hi, Jeff!
I'm planning to provide the review for this patch in future. I've done
some performance tesing (see attachment).
All in all, nothing important, everything works fine.
Tests were executed under current HEAD on Ubuntu 16 over MacBook Air.
I observe that:
1. Patch brings performance improv
Hi, Bruce!
2017-04-25 6:31 GMT+05:00 Bruce Momjian :
> The only unusual thing is that this release has ~180 items while most
> recent release have had ~220. The pattern I see that there are more
> large features in this release than previous ones.
I'm not sure, but, probably, it worth mentioning
Hi, hackers!
I've adapted crossmatch join from pgSphere to cube for performance tests.
I've placed spatial join code here
https://github.com/Octonica/postgres/blob/spatialjoin/contrib/cube/spatialjoin.c
and node code here
https://github.com/Octonica/postgres/blob/spatialjoin/contrib/cube/joinnode.
Hi, Kang and everyone in this thread.
I'm planning to present the online course "Hacking PostgreSQL: data
access methods in action and under the hood" on edX on June 1st. It's
not announced yet, links will be available later.
This course I'm describing information that was crucial for me to
start
Hi, hackers!
Here's a small patch that implements fetch function necessary for
Index Only Scans that use cube data type.
I reuse function g_cube_decompress() instead of creating new function
g_cube_fetch().
Essentially, they both have to detoast data.
How do you think, is it better to create a sh
Hi, hackers!
Currently, GiST stores each attribute in a compressed form.
That is, each time attribute is written it's calling compress
function, and when the attribute is accessed the decompress functions
is called.
Some types can't get any advantage out of this technique since the
context of one
Thanks, Tom!
2017-05-28 22:22 GMT+05:00 Tom Lane :
> Andrew Borodin writes:
>> Maybe we should make compress\decompress functions optional?
>
> 1. You'll need to adjust the documentation (gist.sgml) not just the code.
Sure, I'll check out where compression is mentioned
28 мая 2017 г. 11:15 PM пользователь "Tom Lane" написал:
Andrew Borodin writes:
> 2017-05-28 22:22 GMT+05:00 Tom Lane :
>> 2. If compress/decompress are omitted, then we could support index-only
>> scans all the time, that is a no-op fetch function would work. The
&
2017-05-29 0:00 GMT+05:00 Tom Lane :
> But the opclass's consistent function might expect to be always given an
> untoasted input, in which case you'd need the decompress function to fix
> that up.
In cube data is detoasted at least 4 times before going to
g_cube_internal_consistent(), including o
Hi, Jeff!
Sorry for being late. Actually, I had several unsuccessful attempts to
find something wrong with the patch.
Here's my review.
in pathkey.c
ecs = (EquivalenceClass **) palloc(nClauses * sizeof(EquivalenceClass *));
scores = (int *) palloc(nClauses * sizeof(int));
range_ecs = palloc(nCla
Hi, hackers!
2017-06-01 1:50 GMT+05:00 Kevin Grittner :
> > The main difference between b-tree and gist index while searching for a
> > target tuple is that in gist index, we can determine if there is a match or
> > not at any level of the index.
>
> Agreed. A gist scan can fail at any level, but
2017-06-02 19:42 GMT+05:00 Jeff Davis :
> On Tue, May 30, 2017 at 11:44 PM, Andrew Borodin wrote:
>> 1. Are there any types, which could benefit from Range Merge and are
>> not covered by this patch?
>
> I thought about this for a while, and the only thing I can think of
&
2017-06-13 18:00 GMT+05:00 Shubham Barai :
>
> Project: Explicitly support predicate locks in index AMs besides b-tree
>
Hi, Shubham
Good job!
So, in current HEAD test predicate_gist_2.spec generate false
positives, but with your patch, it does not?
I'd suggest keeping spec tests with your code in
Hi, Dong!
2017-06-15 21:19 GMT+05:00 Yuan Dong :
> I'm going to hack on my own. With the help of Andrew Borodin, I want to
> start the project with adding a third state to collision check. The third
> state is that:
> subtree is totally within the query. In this case, GiST s
Hi, Alexander!
Thanks for looking into the patch!
On Thu, Sep 28, 2017 at 3:59 PM, Alexander Korotkov <
a.korot...@postgrespro.ru> wrote:
>
>
> In gistdoinsert() you do CheckForSerializableConflictIn() only if page
> wasn't exclusively locked before (xlocked is false).
>
> if (!xlocked)
>> {
>>
On Mon, Oct 2, 2017 at 8:00 PM, Alexander Korotkov
wrote:
> What happen if exactly this "continue" fires?
>
>> if (GistFollowRight(stack->page))
>> {
>> if (!xlocked)
>> {
>> LockBuffer(stack->buffer, GIST_UNLOCK);
>> LockBuffer(stack->buffer, GIST_EXCLUSIVE);
>> xlocked = true;
>> /* someone migh
2017-01-10 14:53 GMT+05:00 Alexander Korotkov :
> 1. What project ideas we have?
Hi!
I'd like to propose project on sorting algorithm research. I’m ready
to be a mentor on this project.
===Topic===
Sorting algorithms benchmark and implementation.
===Idea===
Currently the PostgreSQL uses Hoare’s
2017-01-10 14:53 GMT+05:00 Alexander Korotkov :
> 1. What project ideas we have?
I have one more project of interest which I can mentor.
Topic. GiST API advancement
===Idea===
GiST API was designed at the beginning of 90th to reduce boilerplate
code around data access methods over balanced tree.
2017-01-12 9:01 GMT+05:00 Peter Eisentraut :
> On 1/10/17 10:58 AM, Robert Haas wrote:
>> On Thu, Dec 29, 2016 at 5:18 PM, Peter Eisentraut
>> wrote:
>>> For additional entertainment, I include patches that integrate
>>> background sessions into dblink. So dblink can open a connection to a
>>> ba
Hi, Jeff!
Thanks for review!
Here's a patch corrected according to your suggestions.
2017-01-19 11:48 GMT+05:00 Jeff Davis :
> https://www.postgresql.org/message-id/CAJEAwVE4UAmm8fr%2BNW8XTnKV6M--ACoNhL3ES8yoKL2sKhbaiw%40mail.gmail.com
>
> Let me re-summarize what's been done here to make sure I
Hello Jeff!
>Review of the code itself:
How do you think, is there anything else to improve in that patch or
we can mark it as 'Ready for committer'?
I've checked the concurrency algorithm with original work of Lehman
and Yao on B-link-tree. For me everything looks fine (safe, deadlock
free and n
Hi!
2017-01-23 11:32 GMT+05:00 Jeff Davis :
> I have some reservations about the complexity and novelty of the
> approach. I don't think I've seen an approach quite like this one
> before. It seems like the main reason you are using this approach is
> because the btree structure was too simple (no
Hello!
I see your point on alternatives. I will do my best to generate more
ideas on how vacuum can be done withing existing index structure, this
will take a day or two.
In this message I'll answer some questions.
2017-01-23 22:45 GMT+05:00 Jeff Davis :
> 1. I haven't seen the approach before of
2017-01-24 22:29 GMT+05:00 Jeff Davis :
> On Tue, Jan 24, 2017 at 3:18 AM, Andrew Borodin wrote:
>> Technically, approach of locking a subtree is not novel. Lehman and
>> Yao focused on "that any process for manipulating the tree uses only a
>> small (constant) number
2017-01-27 19:14 GMT+05:00 Peter Eisentraut :
> I suppose we should decide first whether we want pg_background as a
> separate extension or rather pursue extending dblink as proposed elsewhere.
>
> I don't know if pg_background allows any use case that dblink can't
> handle (yet).
pg_background in
2017-01-25 12:09 GMT+05:00 Andrew Borodin :
> 2017-01-24 22:29 GMT+05:00 Jeff Davis :
>> By the way, can you show me where the Lehman and Yao paper addresses
>> page recycling?
>
> Here J. Hellerstein comments L&Y paper [1] saying that effectively
> there is no deletio
Hi, Jeff!
2017-02-05 3:45 GMT+05:00 Jeff Davis :
> On Sun, Jan 22, 2017 at 10:32 PM, Jeff Davis wrote:
>> On Sat, Jan 21, 2017 at 4:25 AM, Andrew Borodin wrote:
>> One idea I had that might be simpler is to use a two-stage page
>> delete. The first stage would remove the
Hi hackers!
Here is a patch with more concurrency-friendly vacuum of GIN.
===Short problem statement===
Currently GIN vacuum during cleaning posting tree can lock this tree
for a long time without real need.
===Problem statement===
Vacuum of posting tree (function ginVacuumPostingTree() in ginva
Here is v1 of the patch. Now it has changes for README and contains
more comments clarifying changes of locking model.
Also I will elaborate some more on what is patched. Main portion of
changes is made to function ginVacuumPostingTreeLeaves(). Before the
patch it was traversing tree in depth-firs
This is simply wonderful!
Finaly, I can implement my favorite sleepsort in postgres:
create table input as select round(random()*20) x from generate_series(1,5,1);
create table output(place int,value int);
create sequence s start 1;
create table handles as select pg_background_launch('select
pg_sl
I've read the code and now I have more suggestions.
1. Easy one. The case of different natts of expected and acutal result
throws same errmsg as the case of wrong types.
I think we should assist the user more here
if (natts != tupdesc->natts)
ereport(ERROR,
(errcode(ERRCODE_DATATYPE_M
2016-12-09 18:00 GMT+05:00 Robert Haas :
> It looks like this could be reworked as a client of Peter Eisentraut's
> background sessions code, which I think is also derived from
> pg_background:
>
> http://archives.postgresql.org/message-id/e1c2d331-ee6a-432d-e9f5-dcf85cffa...@2ndquadrant.com
>
> Th
Hi!
I'm planning to review this patch.
I have some questions, maybe answers could help me understand patch better.
1. As far as I can see, we connot use COPY FROM STDIN in bg session?
Since one of purposes is to orchestrate transactions, may be that
would be valuable.
2. From my point of view the
Hi!
Just in case you'd like to include sleepsort as a test, here it is
wrapped as a regression test(see attachment). But it has serious
downside: it runs no less than 5 seconds.
Also I'll list here every parallelism feature I managed to imagine. It
is not to say that I suggest having some of thes
2016-12-13 12:55 GMT+05:00 amul sul :
> I think background-session code is not that much deviated from
> pg_background code,
It is not derived, though it is not much deviated. background sessions
code do not have detailed exceptions and code comments, but it is
doing somewhat similar things.
>IIUC
2016-12-14 20:45 GMT+05:00 Peter Eisentraut :
> On 12/11/16 5:38 AM, Andrew Borodin wrote:
>> 2. From my point of view the interface of the feature is the strong
>> point here (compared to pg_background). But it does not help
>> programmer to follow good practice: bgwor
2016-12-15 0:30 GMT+05:00 Peter Eisentraut :
TryBeginSession()?
>>>
>>> What exactly would that do?
>> Return status (success\failure) and session object, if a function succeeded.
>>
>> If there is max_connections exceeded, then (false,null).
>>
>> I'm not sure whether this idiom is common for
2016-12-16 20:17 GMT+05:00 Peter Eisentraut :
>> And one more thing... Can we have BackgroundSessionExecute() splitted
>> into two parts: start query and wait for results?
>> It would allow pg_background to reuse bgsession's code.
>
> Yes, I will look into that.
Thank you. I'm marking both patches
2016-12-19 4:21 GMT+05:00 David Fetter :
> Couldn't it sleep in increments smaller than a second? Like maybe
> milliseconds? Also, it's probably cleaner (or at least more
> comprehensible) to write something using format() and dollar quoting
> than the line with the double 's.
Right. Here's vers
2016-12-21 4:55 GMT+05:00 David Fetter :
> I see.
>
> I find the following a little easier to follow, and the sleeps still
> work even when very short.
Now I know a little more SQL :) Thank you.
I'm not sure every platform supports microsecond sleeps. But it will
work anyway. This test is determi
2016-12-21 20:42 GMT+05:00 Robert Haas :
> This whole subthread seems like a distraction to me. I find it hard
> to believe that this test case would be stable enough to survive the
> buildfarm where, don't forget, we have things like
> CLOBBER_CACHE_ALWAYS machines where queries take 100x longer
2017-01-03 19:39 GMT+05:00 Peter Eisentraut :
> On 1/3/17 1:26 AM, amul sul wrote:
> > One more requirement for pg_background is session, command_qh,
> > response_qh and worker_handle should be last longer than current
> > memory context, for that we might need to allocate these in
> > TopMemoryCo
2017-01-04 10:23 GMT+05:00 amul sul :
> One more query, can we modify
> BackgroundSessionStart()/BackgroundSession struct to get background
> worker PID as well?
I think since session always has a PID it's absoultley reasonable to return PID.
> I can understand this requirement could be sound usel
Hi!
2017-01-07 11:44 GMT+05:00 amul sul :
> Changes:
> 1. pg_background_launch renamed to pg_background_start
> 2. pg_background_detach renamed to pg_background_close
> 3. Added new api to display previously launch background worker & its
> result count waiting to be read.
Great work!
> Note th
Hi, hackers!
I think there is some room for improving GiST inserts. Following is
the description of what I think is performance problem.
Function gistplacetopage in file /src/backend/access/gist/gist.c is
responsible for updating or appending new tuple on GiST page.
Currently, after checking nece
me sanity checks copied from
PageIndexTupleDelete).
Next weekend I'll do more testing, and then add it to commitfest.
Best regards, Andrey Borodin, Octonica & Ural Federal University.
2016-07-03 15:21 GMT+05:00 Alexander Korotkov :
> Hi!
>
> On Sun, Jul 3, 2016 at 12:24 PM, Andr
Here is a patch with corrections from Alexander Korotkov.
My tests, check and check-world show no problems against Ubuntu LTS 14 x64 VM.
Best regards, Andrey Borodin, Octonica & Ural Federal University.
2016-07-04 10:41 GMT+05:00 Andrew Borodin :
> Hi!
>>I think you sho
th missing spaces later. I also found some more missing
spaces in PageIndexTupleOverwrite call and typo in comments ("on-place").
Best regards, Andrey Borodin, Octonica & Ural Federal University.
2016-07-04 18:58 GMT+05:00 Amit Kapila :
> On Mon, Jul 4, 2016 at 4:52 PM, Andrew Boro
5:00 Alvaro Herrera :
> Andrew Borodin wrote:
>> Thank you, Amit.
>>
>> Currently, if WAL reconstruct page in another order it won't be a problem.
>
> We require that replay of WAL leads to identical bytes than the
> original. Among other things, this enables use of a too
write() should make a call to
ItemIdSetNormal() to pretend it is generic function and not just a
private part of GiST.
Best regards, Andrey Borodin, Octonica & Ural Federal University.
2016-07-04 22:59 GMT+05:00 Andrew Borodin :
> Thank you, Alvaro.
>
> Yes, now I see. I'll update g
ad.
>
> Also I suspect that PageIndexTupleOverwrite() should make a call to
> ItemIdSetNormal() to pretend it is generic function and not just a
> private part of GiST.
>
> Best regards, Andrey Borodin, Octonica & Ural Federal University.
>
> 2016-07-04 22:59 GMT+05:00 Andrew Bor
One more thing came to my mind:
WAL records done by the GiST before patch will corrupt GiST after
patch if replayed.
Is it a problem? May be it's prevented on some higher level?
Best regards, Andrey Borodin, Octonica & Ural Federal University.
2016-07-06 22:11 GMT+05:00 Andrew Borodin
>If a feature changes the shape of WAL records, XLOG_PAGE_MAGIC is bumped to
>prevent any problems.
I've attached patch with a bump, but, obviously, it'll be irrelevant
after any other commit changing WAL shape.
Here is a patch with updated GiST README.
I haven't found apropriate place to describ
>Can you please patch BRIN to use this new function too?
AFAIK Sergey Mirvoda was going to implement and test it.
It is easy to do this optimization for brin_samepage_update (see patch
draft in attachment, make check passes), but WAL of regular BRIN
update is not clear for me.
Best regards, Andrey
>Can you please patch BRIN to use this new function too?
On my machine replacement of both BRIN update cases (see
https://github.com/x4m/pggistopt/commit/a6d301ff79104b977619339d53aebf748045418a
) showed no performance changes on folowing update query (6 seconds of
updates avg):
create table dataT
Hi!
I like the idea and implementation, but I have one suggestion.
> Instead of propagating carry after each new value, it's done only every
> values (or at the end).
I think we could do carry every 0x7FF / 1 accumulation, couldn't we?
Best regards, Andrey Borodin, Octonica & Ural
>I think we could do carry every 0x7FF / 1 accumulation, couldn't we?
I feel that I have to elaborate a bit. Probably my calculations are wrong.
Lets assume we already have accumulated INT_MAX of digits in
previous-place accumulator. That's almost overflow, but that's not
overflow. C
that value 1 is hardcoded
somewhere else, any other value is not recommended and a bunch of code
is left for historical reasons.
Best regards, Andrey Borodin, Octonica & Ural Federal University.
2016-07-27 13:57 GMT+05:00 Dean Rasheed :
> On 27 July 2016 at 07:33, Andrew Borodin wrote:
&
I've tested patch with this query
https://gist.github.com/x4m/fee16ed1a55217528f036983d88771b4
Test specs were: Ubuntu 14 LTS VM, dynamic RAM, hypervisor Windows
Server 2016, SSD disk, core i5-2500. Configuration: out of the box
master make.
On 10 test runs timing of select statement: AVG 3739.8 m
Here is BRIN-compatible version of patch. Now function
PageIndexTupleOverwrite consumes tuple size as a parameter, this
behavior is coherent with PageAddItem.
Also, i had to remove asserstion that item has a storage in the loop
that adjusts line pointers. It would be great if someone could check
th
Anastasia , thank you for your attentive code examine.
2016-08-05 21:19 GMT+05:00 Anastasia Lubennikova :
> First of all, shouldn't we use MAXALIGN(oldsize) instead of oldsize?
> Although, I'm quite sure that it was already aligned somewhere before.
> I doubt that the check (size_diff != MAXALIGN(
Here is new version of the patch, now it includes recommendations from
Anastasia Lubennikova.
I've investigated anamalous index size decrease. Most probable version
appeared to be true.
Cube extension, as some others, use Guttman's polynomial time split
algorithm. It is known to generate "needle-
>So on average in a large randomly filled index, pages
spend more time nearer 50% full than 100% full.
I think we can make this number more...controllable.
Before split we can check whether left and right pages both are in
shared buffer and if they are seriously under certain fillfactor, say
under
> That was a bug caused by high key truncation, that occurs when index has more
> than 3 levels. Fixed.
Affirmative. I've tested index construction with 100M rows and
subsequent execution of select queries using index, works fine.
Best regards, Andrey Borodin, Octonica & Ural Federal University.
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