IDS Forum

Re: Re: PSORT_DBTEMP does not work

Posted By: Art Kagel
Date: Thursday, 20 February 2014, at 7:23 a.m.

In Response To: Antw: Re: PSORT_DBTEMP does not work (Weitkamp Heinz)

The temp table is to hold the sorted rows for the GROUP BY clause. It
needs that because in general you could have a HAVING clause filtering the
results of the GROUP BY so the engine has to be able to perform general
query processing on the results.

Art

Art S. Kagel, Principal Consultant
ASK Database Management

Blog: http://informix-myview.blogspot.com/

Disclaimer: Please keep in mind that my own opinions are my own opinions
and do not reflect on the IIUG, nor any other organization with which I am
associated either explicitly, implicitly, or by inference. Neither do
those opinions reflect those of other individuals affiliated with any
entity with which I am affiliated nor those of the entities themselves.

On Thu, Feb 20, 2014 at 6:52 AM, Weitkamp Heinz <
Heinz.Weitkamp@westfleisch.de> wrote:

> Hello Art,
>
> thanks for the quick reply.
>
> Environment:
> PSORT_DBTEMP=/online
> DBSPACETEMP=tmpdbs
>
> New experiences:
>
> IDS creates the Table _temptable in the temp_dbspace 'tmpdbs'.
> If the temp_dbspace is full then it creates the errormessage:
>
> 264: Could not write to a temporary file.
> 131: ISAM error: no free disk space
>
> If the space of the temp_dbspace is big enough for the created
> _temptable then i see temporary files on /online like:
>
> first:
> srt0086917_013
>
> at the end a few files:
> ove0086899_xxx xxx=various number
>
> What are the 'ovexxxx' files?
>
> The SQL terminates without errors.
>
> Why does ids need the _temptable in the temp_dbspace 'tmpdbs'.
>
> Output of 'set explain on':
>
> QUERY: (OPTIMIZATION TIMESTAMP: 02-20-2014 11:45:15)
> ------
> SELECT AL1.vzswaagnr, AL1.vzszustand, AL1.vzsqualtnr, SUM (
> AL1.vzsgewich
> ), AL1.vzsartnr, AL2.arti_bez, AL1.vzskundennr, AL3.kst_kurz_name
> FROM
> root.vzswiegdat AL1, OUTER root.kulistamm AL3, root.artikel AL2 WHERE
> (
> AL1.vzskundennr = AL3.kst_kulinr AND AL1.vzsmandant =
> AL3.kst_mandant AND AL1.vzsbuchkr = AL3.kst_firma AND
> AL1.vzsartnr=AL2.arti_artinr AND AL1.vzsmandant=AL2.arti_mandant AND
> AL1.vzsfirma=AL2.arti_firma) AND ((AL1.vzsmandant=1 AND
> AL1.vzsfirma=1
> AND AL1.vzsbuchkr=11 AND AL1.vzswerk=11 AND AL1.vzswaagnr IN (22, 23,
> 45,
> 46, 47, 48) AND AL1.vzsdatum>='01.01.2013')) GROUP BY 1, 2, 3, 5, 6,
> 7, 8
> order by 1,2,3,5,6,7,8
>
> Estimated Cost: 3960305
> Estimated # of Rows Returned: 62
> Temporary Files Required For: Order By Group By
>
> 1) root.al2: INDEX PATH
>
> (1) Index Name: root.keyarti2
>
> Index Keys: arti_mandant arti_firma arti_bez
>
> Lower Index Filter: (root.al2.arti_mandant = 1 AND
> root.al2.arti_firma =
> 1 )
>
> 2) root.al1: AUTOINDEX PATH
>
> Filters:
>
> Table Scan Filters: (((root.al1.vzswerk = 11 AND
> root.al1.vzsbuchkr = 11
> ) AND root.al1.vzswaagnr IN (22 , 23 , 45 , 46 , 47 , 48 )) AND
> root.al1.vzsdat
> um >= 01.01.2013 )
>
> (1) Index Name: (Auto Index)
>
> Index Keys: vzsartnr vzsfirma vzsmandant
>
> Lower Index Filter: ((root.al1.vzsartnr = root.al2.arti_artinr
> AND root.
> al1.vzsfirma = root.al2.arti_firma ) AND root.al1.vzsmandant =
> root.al2.arti_man
> dant )
> NESTED LOOP JOIN
>
> 3) root.al3: INDEX PATH
>
> (1) Index Name: root.keykst1
>
> Index Keys: kst_kulinr kst_mandant kst_firma
>
> Lower Index Filter: ((root.al1.vzskundennr = root.al3.kst_kulinr
> AND roo
> t.al1.vzsbuchkr = root.al3.kst_firma ) AND root.al1.vzsmandant =
> root.al3.kst_ma
> ndant )
> NESTED LOOP JOIN
>
> Query statistics:
> -----------------
> Table map :
> ----------------------------
> Internal name Table name
> ----------------------------
> t1 al2
> t2 al1
> t3 al1
> t4 al3
>
> type table rows_prod est_rows rows_scan time est_cost
> -------------------------------------------------------------------
> scan t1 16135 24443 16135 00:20.09 18842
>
> type table rows_prod est_rows rows_scan time est_cost
> -------------------------------------------------------------------
> scan t2 1507671 100 6452883 01:18.05 1
>
> type table rows_prod est_rows rows_scan time est_cost
> -------------------------------------------------------------------
> scan t3 1507671 100 1507671 06:04.08 1
>
> type rows_prod est_rows time est_cost
> -------------------------------------------------
> nljoin 1507671 126 06:24.45 3960046
>
> type table rows_prod est_rows rows_scan time est_cost
> -------------------------------------------------------------------
> scan t4 0 302 0 00:10.46 1
>
> type rows_prod est_rows time est_cost
> -------------------------------------------------
> nljoin 1507671 126 06:35.72 3960123
>
> type rows_prod est_rows rows_cons time es
> t_cost
> ------------------------------------------------------------
> group 1154 63 1507671 06:40.98 170
>
> type rows_sort est_rows rows_cons time est_cost
> ------------------------------------------------------------
> sort 57 63 1154 06:40.98 12
>
> >>> "Art Kagel" <art.kagel@gmail.com> 19.02.2014 16:24 >>>
> Heinz:
>
> There are two possibilities:
> 1) The sort is fitting completely in memory, so no sort-work files are
>
> needed.
> 2) The row ordering needed by the GROUP BY and ORDER by clauses are
> being
> satisfied by an index.
>
> You can check the former while the session is still open by looking at
> the
> session's record in the sysmaster:syssesprof table. That will show the
>
> number of disk sorts performed by the session and the total number of
> sorts
> as well as the size of the largest sort. The second condition could be
>
> verified by running the query under SET EXPLAIN ON to see if the query
> plan
> is including a sort or not.
>
> FYI: For best performance set PSORT_DBTEMP to at least three and as
> many as
> six completely independent filesystems if possible.
>
> Art
>
> Art S. Kagel, Principal Consultant
> ASK Database Management
>
> Blog: http://informix-myview.blogspot.com/
>
> Disclaimer: Please keep in mind that my own opinions are my own
> opinions
> and do not reflect on the IIUG, nor any other organization with which I
> am
> associated either explicitly, implicitly, or by inference. Neither do
> those opinions reflect those of other individuals affiliated with any
> entity with which I am affiliated nor those of the entities themselves.
>
> On Wed, Feb 19, 2014 at 10:16 AM, Weitkamp Heinz <
> Heinz.Weitkamp@westfleisch.de> wrote:
>
> > Hello,
> >
> > IBM Informix Dynamic Server Version 11.70.UC7W3
> > SUSE Linux Enterprise Server 11 (i586) VERSION = 11 PATCHLEVEL = 1
> >
> > I set:
> > export PSORT_DBTEMP=/online
> >
> > env|grep PSO
> > PSORT_DBTEMP=/online
> >
> > If I create an Index (with dbaccess) the sortfiles where created in
> the
> > directory /online
> >
> > ls -l /online
> > -rw------- 1 root informix 90963968 Feb 19 15:48 srt0086779_001
> >
> > When I started an sql like:
> >
> > Select .............. from ..... GROUP BY 1, 2, 3, 5, 6, 7, 8 order
> > by 1,2,3,5,6,7,8;
> >
> > nothing where created in the directory /online.
> > Why not?
> >
> > Doku says:
> > The PSORT_DBTEMP environment variable specifies the location where
> the
> > database server writes the temporary files that the PSORT_NPROCS
> > environment variable uses to perform a sort.
> > The database server uses the directory that PSORT_DBTEMP specifies,
> > even if the environment variable PSORT_NPROCS is not set.
> >
> > The sortfiles where created in the Temp-Dbspace 'tmpdbs'.
> >
> > onstat -d:
> > 5ff73018 4 0x2001 6 1 2048 N T A
> > informix tmpdbs
> >
> > The onconfig has the parameter:
> > DBSPACETEMP tmpdbs
> >
> > Any hints would be appreciated
> >
> > Thanks
> > Heinz
> >
> > --
> > WESTFLEISCH eG * Hauptsitz: Brockhoffstr. 11, 48143 Münster
> > Amtsgericht Münster: Gen.-Reg. 307
> >
> > Aufsichtsratsvorsitzender: Josef Lehmenkühler
> > Vorstand: Dirk Niederstucke (Vorsitzender); Peter Piekenbrock;
> Gerhard
> > Meierzuherde; Dr. Helfried Giesen, Geschäftsführer (Sprecher);
> Carsten
> > Schruck, Geschäftsführer
> >
> > Hinweise: Es können nur Mails bis 30 MB empfangen werden.
> > PowerPoint-Dateien müssen in eine ZIP-Datei gepackt werden.
> > --------------------------------------------------
> >
> >
> >
> >
>
>
> *******************************************************************************
>
> > Forum Note: Use "Reply" to post a response in the discussion forum.
> >
> >
>
> --001a11349a0253ac6b04f2c3fd1b
>
>
>
> *******************************************************************************
>
> Forum Note: Use "Reply" to post a response in the discussion forum.
>
> --
> WESTFLEISCH eG * Hauptsitz: Brockhoffstr. 11, 48143 Münster
> Amtsgericht Münster: Gen.-Reg. 307
>
> Aufsichtsratsvorsitzender: Josef Lehmenkühler
> Vorstand: Dirk Niederstucke (Vor
> sitzender); Peter Piekenbrock; Gerhard
> Meierzuherde; Dr. Helfried Giesen, Geschäftsführer (Sprecher); Carsten
> Schruck, Geschäftsführer
>
> Hinweise: Es können nur Mails bis 30 MB empfangen werden.
> PowerPoint-Dateien müssen in eine ZIP-Datei gepackt werden.
> --------------------------------------------------
>
>
>
> *******************************************************************************
> Forum Note: Use "Reply" to post a response in the discussion forum.
>
>

--047d7b3431ea12e21904f2d59435

Messages In This Thread

• PSORT_DBTEMP does not work
  Weitkamp Heinz -- Wednesday, 19 February 2014, at 10:16 a.m.
  • Re: PSORT_DBTEMP does not work
    Art Kagel -- Wednesday, 19 February 2014, at 10:24 a.m.
    • Antw: Re: PSORT_DBTEMP does not work
      Weitkamp Heinz -- Thursday, 20 February 2014, at 6:52 a.m.
      • Re: Re: PSORT_DBTEMP does not work
        Fernando Nunes -- Thursday, 20 February 2014, at 7:10 a.m.
        • Re: Re: PSORT_DBTEMP does not work
          Art Kagel -- Thursday, 20 February 2014, at 7:30 a.m.
          • Antw: Re: Re: PSORT_DBTEMP does not work
            Weitkamp Heinz -- Thursday, 20 February 2014, at 8:00 a.m.
      • Re: Re: PSORT_DBTEMP does not work
        Art Kagel -- Thursday, 20 February 2014, at 7:23 a.m.

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