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pgsql: Fix TransactionIdIsCurrentTransactionId() to use binary search
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* pgsql: Fix TransactionIdIsCurrentTransactionId() to use binary search
@ 2008-03-17 02:18  Tom Lane <tgl@postgresql.org>
  0 siblings, 1 reply; 13+ messages in thread

From: tgl@postgresql.org @ 2008-03-17 02:18 UTC (permalink / raw)
  To: pgsql-committers@postgresql.org

Log Message:
-----------
Fix TransactionIdIsCurrentTransactionId() to use binary search instead of
linear search when checking child-transaction XIDs.  This makes for an
important speedup in transactions that have large numbers of children,
as in a recent example from Craig Ringer.  We can also get rid of an
ugly kluge that represented lists of TransactionIds as lists of OIDs.

Heikki Linnakangas

Modified Files:
--------------
    pgsql/src/backend/access/transam:
        twophase.c (r1.39 -> r1.40)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/twophase.c?r1=1.39&r2=...)
        xact.c (r1.258 -> r1.259)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/xact.c?r1=1.258&r2=1.2...)
    pgsql/src/include/nodes:
        pg_list.h (r1.57 -> r1.58)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/nodes/pg_list.h?r1=1.57&r2=1.58)



^ permalink  raw  reply  [nested|flat] 13+ messages in thread

* Re: [COMMITTERS] pgsql: Fix TransactionIdIsCurrentTransactionId() to use binary search
@ 2008-03-27 20:56  Robert Treat <xzilla@users.sourceforge.net>
  parent: Tom Lane <tgl@postgresql.org>
  0 siblings, 1 reply; 13+ messages in thread

From: Robert Treat @ 2008-03-27 20:56 UTC (permalink / raw)
  To: pgsql-hackers@postgresql.org; +Cc: Tom Lane <tgl@postgresql.org>

On Sunday 16 March 2008 22:18, Tom Lane wrote:
> Log Message:
> -----------
> Fix TransactionIdIsCurrentTransactionId() to use binary search instead of
> linear search when checking child-transaction XIDs.  This makes for an
> important speedup in transactions that have large numbers of children,
> as in a recent example from Craig Ringer.  We can also get rid of an
> ugly kluge that represented lists of TransactionIds as lists of OIDs.
>

Are there any plans to backpatch this into REL8_3_STABLE?  It looks like I am  
hitting a pretty serious performance regression on 8.3 with a stored 
procedure that grabs a pretty big recordset, and loops through doing 
insert....update on unique failures.  The procedure get progressivly slower 
the more records involved... and dbx shows me stuck in 
TransactionIdIsCurrentTransactionId().  I can provide provide more details if 
needed (lmk what your looking for) but it certainly looks like the issue 
discussed here: 
http://archives.postgresql.org/pgsql-performance/2008-03/msg00191.php

-- 
Robert Treat
Build A Brighter LAMP :: Linux Apache {middleware} PostgreSQL



^ permalink  raw  reply  [nested|flat] 13+ messages in thread

* Re: [COMMITTERS] pgsql: Fix TransactionIdIsCurrentTransactionId() to use binary search
@ 2008-03-27 21:11  Tom Lane <tgl@sss.pgh.pa.us>
  parent: Robert Treat <xzilla@users.sourceforge.net>
  0 siblings, 2 replies; 13+ messages in thread

From: Tom Lane @ 2008-03-27 21:11 UTC (permalink / raw)
  To: Robert Treat <xzilla@users.sourceforge.net>; +Cc: pgsql-hackers@postgresql.org

Robert Treat <xzilla@users.sourceforge.net> writes:
> On Sunday 16 March 2008 22:18, Tom Lane wrote:
>> Fix TransactionIdIsCurrentTransactionId() to use binary search instead of
>> linear search when checking child-transaction XIDs.

> Are there any plans to backpatch this into REL8_3_STABLE?

No.

> It looks like I am  
> hitting a pretty serious performance regression on 8.3 with a stored 
> procedure that grabs a pretty big recordset, and loops through doing 
> insert....update on unique failures.  The procedure get progressivly slower 
> the more records involved... and dbx shows me stuck in 
> TransactionIdIsCurrentTransactionId().

If you can convince me it's a regression I might reconsider, but I
rather doubt that 8.2 was better,

			regards, tom lane



^ permalink  raw  reply  [nested|flat] 13+ messages in thread

* Re: [COMMITTERS] pgsql: Fix TransactionIdIsCurrentTransactionId() to use binary search
@ 2008-03-28 05:51  Robert Treat <xzilla@users.sourceforge.net>
  parent: Tom Lane <tgl@sss.pgh.pa.us>
  1 sibling, 1 reply; 13+ messages in thread

From: Robert Treat @ 2008-03-28 05:51 UTC (permalink / raw)
  To: Tom Lane <tgl@sss.pgh.pa.us>; +Cc: pgsql-hackers@postgresql.org

On Thursday 27 March 2008 17:11, Tom Lane wrote:
> Robert Treat <xzilla@users.sourceforge.net> writes:
> > On Sunday 16 March 2008 22:18, Tom Lane wrote:
> >> Fix TransactionIdIsCurrentTransactionId() to use binary search instead
> >> of linear search when checking child-transaction XIDs.
> >
> > Are there any plans to backpatch this into REL8_3_STABLE?
>
> No.
>
> > It looks like I am
> > hitting a pretty serious performance regression on 8.3 with a stored
> > procedure that grabs a pretty big recordset, and loops through doing
> > insert....update on unique failures.  The procedure get progressivly
> > slower the more records involved... and dbx shows me stuck in
> > TransactionIdIsCurrentTransactionId().
>
> If you can convince me it's a regression I might reconsider, but I
> rather doubt that 8.2 was better,
>

Well, I can't speak for 8.2, but I have a second system crunching the same 
data using the same function on 8.1 (on lesser hardware in fact), and it 
doesn't have these type of issues.  Looking over the past week, the 8.3 box 
averages about 19 minutes to complete each run, and the 8.1 box averages 15 
minutes (sample size is over 100 iterations of both).  Of course this is when 
it completes, the 8.3 box often does not complete, as it falls farther behind 
during the day and eventually cannot finish (it does periodic intra-day 
summing, so there's a limited time frame it has to run, and it's jobs end up 
taking hours to complete). 

I am open to the idea that there is some other issue going on here, but 
whenever I look at it, it seems stuck in 
TransactionIdIsCurrentTransactionId(), progress for the function does get 
increasingly slower as it progresses, and I can watch the process consuming 
more and more memory as it goes on...  I can probably get some dtrace output 
tommorrow if you want. 

-- 
Robert Treat
Build A Brighter LAMP :: Linux Apache {middleware} PostgreSQL



^ permalink  raw  reply  [nested|flat] 13+ messages in thread

* Re: [COMMITTERS] pgsql: Fix TransactionIdIsCurrentTransactionId() to use binary search
@ 2008-03-28 05:55  Tom Lane <tgl@sss.pgh.pa.us>
  parent: Robert Treat <xzilla@users.sourceforge.net>
  0 siblings, 0 replies; 13+ messages in thread

From: Tom Lane @ 2008-03-28 05:55 UTC (permalink / raw)
  To: Robert Treat <xzilla@users.sourceforge.net>; +Cc: pgsql-hackers@postgresql.org

Robert Treat <xzilla@users.sourceforge.net> writes:
>> If you can convince me it's a regression I might reconsider, but I
>> rather doubt that 8.2 was better,

> Well, I can't speak for 8.2, but I have a second system crunching the same 
> data using the same function on 8.1 (on lesser hardware in fact), and it 
> doesn't have these type of issues.

If you can condense it to a test case that is worse on 8.3 than 8.1,
I'm willing to listen...

			regards, tom lane



^ permalink  raw  reply  [nested|flat] 13+ messages in thread

* Re: [HACKERS] [COMMITTERS] pgsql: Fix TransactionIdIsCurrentTransactionId() to use binary search
@ 2008-04-21 16:29  Robert Treat <xzilla@users.sourceforge.net>
  parent: Tom Lane <tgl@sss.pgh.pa.us>
  1 sibling, 1 reply; 13+ messages in thread

From: Robert Treat @ 2008-04-21 16:29 UTC (permalink / raw)
  To: pgsql-performance

On Thursday 27 March 2008 17:11, Tom Lane wrote:
> Robert Treat <xzilla@users.sourceforge.net> writes:
> > On Sunday 16 March 2008 22:18, Tom Lane wrote:
> > > > > Fix TransactionIdIsCurrentTransactionId() to use binary 
> > > > > search instead 
> > > > > of linear search when checking child-transaction XIDs.
> >
> > > > Are there any plans to backpatch this into REL8_3_STABLE?
> > >
> > >  No.
> > >
> > > > It looks like I am
> > > > hitting a pretty serious performance regression on 8.3 with a stored
> > > > procedure that grabs a pretty big recordset, and loops through doing
> > > > insert....update on unique failures.  The procedure get progressivly
> > > > slower the more records involved... and dbx shows me stuck in
> > > > TransactionIdIsCurrentTransactionId().
> > >
> > > If you can convince me it's a regression I might reconsider, but I
> > > rather doubt that 8.2 was better,
> > > 

> > Well, I can't speak for 8.2, but I have a second system crunching the
> > same data using the same function on 8.1 (on lesser hardware in fact),
> > and it doesn't have these type of issues.
>
> If you can condense it to a test case that is worse on 8.3 than 8.1,
> I'm willing to listen...

I spent some time trying to come up with a test case, but had no luck.  Dtrace 
showed that the running process was calling this function rather excessively; 
sample profiling for 30 seconds would look like this: 

FUNCTION                                                COUNT   PCNT
<snip>
postgres`LockBuffer                                        10   0.0%
postgres`slot_deform_tuple                                 11   0.0%
postgres`ExecEvalScalarVar                                 11   0.0%
postgres`ExecMakeFunctionResultNoSets                      13   0.0%
postgres`IndexNext                                         14   0.0%
postgres`slot_getattr                                      15   0.0%
postgres`LWLockRelease                                     20   0.0%
postgres`index_getnext                                     55   0.1%
postgres`TransactionIdIsCurrentTransactionId            40074  99.4%

But I saw similar percentages on the 8.1 machine, so I am not convinced this 
is where the problem is.  Unfortunatly (in some respects) the problem went 
away up untill this morning, so I haven't been looking at it since the above 
exchange.  I'm still open to the idea that something inside 
TransactionIdIsCurrentTransactionId could have changed to make things worse 
(in addition to cpu, the process does consume a significant amount of 
memory... prstat shows:

 PID USERNAME  SIZE   RSS STATE  PRI NICE      TIME  CPU PROCESS/NLWP
 3844 postgres 1118M 1094M cpu3    50    0   6:25:48  12% postgres/1

I do wonder if the number of rows being worked on is significant in some 
way... by looking in the job log for the running procedure (we use 
autonoumous logging in this function), I can see that it has a much larger 
number of rows to be processed, so perhaps there is simply a tipping point 
that is reached which causes it to stop performing... still it would be 
curious that I never saw this behavior on 8.1

= current job
     elapsed     |                         status
-----------------+--------------------------------------------------------
 00:00:00.042895 | OK/starting with 2008-04-21 03:20:03
 00:00:00.892663 | OK/processing 487291 hits up until 2008-04-21 05:20:03
 05:19:26.595508 | ??/Processed 70000 aggregated rows so far
(3 rows)

= yesterdays run
|     elapsed     |                         status
+-----------------+--------------------------------------------------------
| 00:00:00.680222 | OK/starting with 2008-04-20 04:20:02
| 00:00:00.409331 | OK/processing 242142 hits up until 2008-04-20 05:20:04
| 00:25:02.306736 | OK/Processed 35936 aggregated rows
| 00:00:00.141179 | OK/
(4 rows)

Unfortunatly I don't have the 8.1 system to bang on anymore for this, (though 
anecdotaly speaking, I never saw this behavior in 8.1) however I do now have 
a parallel 8.3 system crunching the data, and it is showing the same symptom 
(yes, 2 8.3 servers, crunching the same data, both bogged down now), so I do 
feel this is something specific to 8.3.  

I am mostly wondering if anyone else has encountered behavior like this on 8.3 
(large sets of insert....update exception block in plpgsql bogging down), or 
if anyone has any thoughts on which direction I should poke at it from here. 
TIA.

-- 
Robert Treat
Build A Brighter LAMP :: Linux Apache {middleware} PostgreSQL



^ permalink  raw  reply  [nested|flat] 13+ messages in thread

* Re: Re: [HACKERS] [COMMITTERS] pgsql: Fix TransactionIdIsCurrentTransactionId() to use binary search
@ 2008-04-21 16:54  Alvaro Herrera <alvherre@commandprompt.com>
  parent: Robert Treat <xzilla@users.sourceforge.net>
  0 siblings, 1 reply; 13+ messages in thread

From: Alvaro Herrera @ 2008-04-21 16:54 UTC (permalink / raw)
  To: Robert Treat <xzilla@users.sourceforge.net>; +Cc: pgsql-performance

Robert Treat wrote:

> Unfortunatly I don't have the 8.1 system to bang on anymore for this, (though 
> anecdotaly speaking, I never saw this behavior in 8.1) however I do now have 
> a parallel 8.3 system crunching the data, and it is showing the same symptom 
> (yes, 2 8.3 servers, crunching the same data, both bogged down now), so I do 
> feel this is something specific to 8.3.  
> 
> I am mostly wondering if anyone else has encountered behavior like this on 8.3 
> (large sets of insert....update exception block in plpgsql bogging down), or 
> if anyone has any thoughts on which direction I should poke at it from here. 
> TIA.

Perhaps what you could do is backpatch the change and see if the problem
goes away.

-- 
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.



^ permalink  raw  reply  [nested|flat] 13+ messages in thread

* Re: Re: [HACKERS] [COMMITTERS] pgsql: Fix TransactionIdIsCurrentTransactionId() to use binary search
@ 2008-04-25 21:24  Robert Treat <xzilla@users.sourceforge.net>
  parent: Alvaro Herrera <alvherre@commandprompt.com>
  0 siblings, 1 reply; 13+ messages in thread

From: Robert Treat @ 2008-04-25 21:24 UTC (permalink / raw)
  To: Alvaro Herrera <alvherre@commandprompt.com>; +Cc: pgsql-performance

On Monday 21 April 2008 12:54, Alvaro Herrera wrote:
> Robert Treat wrote:
> > Unfortunatly I don't have the 8.1 system to bang on anymore for this,
> > (though anecdotaly speaking, I never saw this behavior in 8.1) however I
> > do now have a parallel 8.3 system crunching the data, and it is showing
> > the same symptom (yes, 2 8.3 servers, crunching the same data, both
> > bogged down now), so I do feel this is something specific to 8.3.
> >
> > I am mostly wondering if anyone else has encountered behavior like this
> > on 8.3 (large sets of insert....update exception block in plpgsql bogging
> > down), or if anyone has any thoughts on which direction I should poke at
> > it from here. TIA.
>
> Perhaps what you could do is backpatch the change and see if the problem
> goes away.

So, after some more digging, we ended up backpatching the change. Results as 
follows:

= hanging job before patch

     elapsed     |                         status
-----------------+--------------------------------------------------------
 00:00:00.024075 | OK/starting with 2008-04-25 08:20:02
 00:00:00.611411 | OK/processing 624529 hits up until 2008-04-25 10:20:02
 03:48:02.748319 | ??/Processed 65000 aggregated rows so far
(3 rows)

= successful job after patch

     elapsed     |                         status
-----------------+---------------------------------------------------------
 00:00:00.026809 | OK/starting with 2008-04-25 08:20:02
 00:00:03.921532 | OK/processing 2150115 hits up until 2008-04-25 15:00:02
 00:24:45.439081 | OK/Processed 334139 aggregated rows
 00:00:00.019433 | OK/
(4 rows)

Note the second run had to do all the rows from the first run, plus additional 
rows that accumulated while the first job was running. 

Oddly some dtrace profiling gave me this, which is pretty different, but 
certainly doesn't have concerns about TransactionIdIsCurrentTransactionId

<snip>
postgres`hash_search_with_hash_value                      536   2.3%
postgres`SearchCatCache                                   538   2.3%
postgres`hash_seq_search                                  577   2.4%
postgres`MemoryContextAllocZeroAligned                    610   2.6%
postgres`_bt_compare                                      671   2.8%
libc.so.1`memcpy                                          671   2.8%
postgres`XLogInsert                                       755   3.2%
postgres`LockReassignCurrentOwner                         757   3.2%
postgres`base_yyparse                                    1174   5.0%
postgres`AllocSetAlloc                                   1244   5.3%

We still have one of our 8.3 servers running stock 8.3.1, so we'll see how 
long before this bites us again.  Would certainly be nice to get this fixed 
in the mainline code. 

-- 
Robert Treat
Build A Brighter LAMP :: Linux Apache {middleware} PostgreSQL



^ permalink  raw  reply  [nested|flat] 13+ messages in thread

* Re: Re: [HACKERS] [COMMITTERS] pgsql: Fix TransactionIdIsCurrentTransactionId() to use binary search
@ 2008-04-25 21:32  Tom Lane <tgl@sss.pgh.pa.us>
  parent: Robert Treat <xzilla@users.sourceforge.net>
  0 siblings, 1 reply; 13+ messages in thread

From: Tom Lane @ 2008-04-25 21:32 UTC (permalink / raw)
  To: Robert Treat <xzilla@users.sourceforge.net>; +Cc: Alvaro Herrera <alvherre@commandprompt.com>; pgsql-performance

Robert Treat <xzilla@users.sourceforge.net> writes:
> Oddly some dtrace profiling gave me this, which is pretty different, but 
> certainly doesn't have concerns about TransactionIdIsCurrentTransactionId

... which seems to pretty much destroy your thesis, no?

			regards, tom lane



^ permalink  raw  reply  [nested|flat] 13+ messages in thread

* Re: Re: [HACKERS] [COMMITTERS] pgsql: Fix TransactionIdIsCurrentTransactionId() to use binary search
@ 2008-04-26 13:10  Robert Treat <xzilla@users.sourceforge.net>
  parent: Tom Lane <tgl@sss.pgh.pa.us>
  0 siblings, 1 reply; 13+ messages in thread

From: Robert Treat @ 2008-04-26 13:10 UTC (permalink / raw)
  To: pgsql-performance; +Cc: Tom Lane <tgl@sss.pgh.pa.us>; Alvaro Herrera <alvherre@commandprompt.com>

On Friday 25 April 2008 17:32, Tom Lane wrote:
> Robert Treat <xzilla@users.sourceforge.net> writes:
> > Oddly some dtrace profiling gave me this, which is pretty different, but
> > certainly doesn't have concerns about TransactionIdIsCurrentTransactionId
>
> .... which seems to pretty much destroy your thesis, no?
>

How so? Before the patch we bog down for hours, spending 99% of our time in  
TransactionIdIsCurrentTransactionId, after the patch everything performs well 
(really better than before) and we spend so little time in 
TransactionIdIsCurrentTransactionId it barely shows up on the radar. 

Note I'm open to the idea that TransactionIdIsCurrentTransactionId itself is 
not the problem, but that something else changed between 8.1 and 8.3 that 
exposes TransactionIdIsCurrentTransactionId as a problem.  Changing to a 
binary search for TransactionIdIsCurrentTransactionId  makes that a non-issue 
though. 

-- 
Robert Treat
Build A Brighter LAMP :: Linux Apache {middleware} PostgreSQL



^ permalink  raw  reply  [nested|flat] 13+ messages in thread

* Re: Re: [HACKERS] [COMMITTERS] pgsql: Fix TransactionIdIsCurrentTransactionId() to use binary search
@ 2008-04-26 17:26  Tom Lane <tgl@sss.pgh.pa.us>
  parent: Robert Treat <xzilla@users.sourceforge.net>
  0 siblings, 1 reply; 13+ messages in thread

From: Tom Lane @ 2008-04-26 17:26 UTC (permalink / raw)
  To: Robert Treat <xzilla@users.sourceforge.net>; +Cc: pgsql-performance@postgresql.org, Alvaro Herrera <alvherre@commandprompt.com>

Robert Treat <xzilla@users.sourceforge.net> writes:
> On Friday 25 April 2008 17:32, Tom Lane wrote:
>> Robert Treat <xzilla@users.sourceforge.net> writes:
>>> Oddly some dtrace profiling gave me this, which is pretty different, but
>>> certainly doesn't have concerns about TransactionIdIsCurrentTransactionId
>> 
>> .... which seems to pretty much destroy your thesis, no?

> How so? Before the patch we bog down for hours, spending 99% of our time in  
> TransactionIdIsCurrentTransactionId, after the patch everything performs well
> (really better than before) and we spend so little time in 
> TransactionIdIsCurrentTransactionId it barely shows up on the radar. 

Oh, you failed to state that the dtrace output was post-patch.  You need
to show *pre* patch dtrace output if you want us to think it relevant.

			regards, tom lane



^ permalink  raw  reply  [nested|flat] 13+ messages in thread

* Re: Re: [HACKERS] [COMMITTERS] pgsql: Fix TransactionIdIsCurrentTransactionId() to use binary search
@ 2008-04-26 18:20  Robert Treat <xzilla@users.sourceforge.net>
  parent: Tom Lane <tgl@sss.pgh.pa.us>
  0 siblings, 1 reply; 13+ messages in thread

From: Robert Treat @ 2008-04-26 18:20 UTC (permalink / raw)
  To: Tom Lane <tgl@sss.pgh.pa.us>; +Cc: pgsql-performance@postgresql.org, Alvaro Herrera <alvherre@commandprompt.com>

On Saturday 26 April 2008 13:26, Tom Lane wrote:
> Robert Treat <xzilla@users.sourceforge.net> writes:
> > On Friday 25 April 2008 17:32, Tom Lane wrote:
> >> Robert Treat <xzilla@users.sourceforge.net> writes:
> >>> Oddly some dtrace profiling gave me this, which is pretty different,
> >>> but certainly doesn't have concerns about
> >>> TransactionIdIsCurrentTransactionId
> >>
> >> .... which seems to pretty much destroy your thesis, no?
> >
> > How so? Before the patch we bog down for hours, spending 99% of our time
> > in TransactionIdIsCurrentTransactionId, after the patch everything
> > performs well (really better than before) and we spend so little time in
> > TransactionIdIsCurrentTransactionId it barely shows up on the radar.
>
> Oh, you failed to state that the dtrace output was post-patch.  You need
> to show *pre* patch dtrace output if you want us to think it relevant.
>

Please read up-thread. 

-- 
Robert Treat
Build A Brighter LAMP :: Linux Apache {middleware} PostgreSQL



^ permalink  raw  reply  [nested|flat] 13+ messages in thread

* Re: Re: [HACKERS] [COMMITTERS] pgsql: Fix TransactionIdIsCurrentTransactionId() to use binary search
@ 2008-04-26 23:20  Tom Lane <tgl@sss.pgh.pa.us>
  parent: Robert Treat <xzilla@users.sourceforge.net>
  0 siblings, 0 replies; 13+ messages in thread

From: Tom Lane @ 2008-04-26 23:20 UTC (permalink / raw)
  To: Robert Treat <xzilla@users.sourceforge.net>; +Cc: pgsql-performance@postgresql.org, Alvaro Herrera <alvherre@commandprompt.com>

Robert Treat <xzilla@users.sourceforge.net> writes:
> On Saturday 26 April 2008 13:26, Tom Lane wrote:
>> Oh, you failed to state that the dtrace output was post-patch.  You need
>> to show *pre* patch dtrace output if you want us to think it relevant.

> Please read up-thread. 

Sorry, I'd forgotten your previous post.

I poked around for calls to TransactionIdIsCurrentTransactionId that
are in current code and weren't in 8.1.  I found these:

src/backend/commands/analyze.c: 965: 					if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(targtuple.t_data)))
src/backend/commands/analyze.c: 984: 					if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(targtuple.t_data)))
src/backend/commands/cluster.c: 803: 				if (!TransactionIdIsCurrentTransactionId(
src/backend/commands/cluster.c: 816: 				if (!TransactionIdIsCurrentTransactionId(
src/backend/storage/ipc/procarray.c: 374: 	if (TransactionIdIsCurrentTransactionId(xid))
src/backend/utils/time/combocid.c: 108: 	Assert(TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(tup)));
src/backend/utils/time/combocid.c: 123: 	Assert(TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(tup)));
src/backend/utils/time/combocid.c: 156: 		TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(tup)))

The ANALYZE and CLUSTER calls are not likely to be your issue, but the
one in HeapTupleHeaderAdjustCmax could get called a lot, and the one
in TransactionIdIsInProgress definitely will get called a lot.
Neither of those calls existed in 8.2.

So I think that explains why TransactionIdIsCurrentTransactionId has
become more performance-critical in 8.3 than it was before.  Will
apply the back-patch.

			regards, tom lane



^ permalink  raw  reply  [nested|flat] 13+ messages in thread


end of thread, other threads:[~2008-04-26 23:20 UTC | newest]

Thread overview: 13+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2008-03-17 02:18 pgsql: Fix TransactionIdIsCurrentTransactionId() to use binary search Tom Lane <tgl@postgresql.org>
2008-03-27 20:56 ` Robert Treat <xzilla@users.sourceforge.net>
2008-03-27 21:11   ` Tom Lane <tgl@sss.pgh.pa.us>
2008-03-28 05:51     ` Robert Treat <xzilla@users.sourceforge.net>
2008-03-28 05:55       ` Tom Lane <tgl@sss.pgh.pa.us>
2008-04-21 16:29     ` Robert Treat <xzilla@users.sourceforge.net>
2008-04-21 16:54       ` Alvaro Herrera <alvherre@commandprompt.com>
2008-04-25 21:24         ` Robert Treat <xzilla@users.sourceforge.net>
2008-04-25 21:32           ` Tom Lane <tgl@sss.pgh.pa.us>
2008-04-26 13:10             ` Robert Treat <xzilla@users.sourceforge.net>
2008-04-26 17:26               ` Tom Lane <tgl@sss.pgh.pa.us>
2008-04-26 18:20                 ` Robert Treat <xzilla@users.sourceforge.net>
2008-04-26 23:20                   ` Tom Lane <tgl@sss.pgh.pa.us>

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