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Re: What are DD_HASHSIZE and DD_HASHMAX? How are they tuned?

Posted in 2000

Topics: Server Administration, Platform-Specific Issues, Versions, Editions & End-of-Life

Francisco Huezo — — source: Informix-list mailing list archive (1991-1998)

Art. I only have one question more. These parameters apply to IDS 7.31 El Fri, 29 Sep 2000, Art S. Kagel escribi': > Francisco Huezo wrote: > > > > Hi. > > > > The true is these couple of parameter are new for me. > > DD_HASHSIZE and DD_HASHMAX.> > > I looked up the Administrator's and Performace guide for IDS 7.31 > > and i can't find anything about them. > > > > In the forum, I learned something but i think is not enough, so far I guess > > they allow tunning the dicctionary cache and these parameter I have to add into > > onconfig file. > > Correct. They are mostly undocumented. See my chapter in the Informix > Handbook for others. > > > But, what are the correct values that they will have? > > How do I know if the server is correctly tunning? > > The value of DD_HASHSIZE must be a prime number and DD_HASHMAX a > smallish integer. The former is the number of hash buckets the latter > the number of slots in each bucket. The product of the two is the > maximum number of tables the dictionary hash table will hold but > hashing realities makes the actual count somewhat less. Someone posted > a script that purports to approximate the tablename hash that the > engine uses to assign tables to buckets so you can calculate a good > DD_HASHMAX for a given DD_HASHSIZE and play with different values of > the latter. > > Art S. Kagel > > > > Could somebody explain them to me or where can I find a information. > > > > Thank a lot for your advices. > > > > -- > > Francisco Huezo > > Administrador de Base de Datos > > Ministerio de Hacienda > > Proyecto SAFI > > Cond. Tres Torres, T-2, N-8 > > San Salvador, El Salvador > > Tel. (503) 225-3700 ext 102 > > Cel: (503) 830-7469 > > ------------------------------------------------- > > Brainbench Certified > > Power Builder 6.0 > > Informix DBA > > Unix Administration ( General ) > > http://www.brainbench.com/transcript.jsp?pid=23525 > > -------------------------------------------------- > > Moving to Linux is more evolution than revolution. -- Francisco Huezo Administrador de Base de Datos Ministerio de Hacienda Proyecto SAFI Cond. Tres Torres, T-2, N-8 San Salvador, El Salvador Tel. (503) 225-3700 ext 102 Cel: (503) 830-7469 ------------------------------------------------- Brainbench Certified Power Builder 6.0 Informix DBA Unix Administration ( General ) http://www.brainbench.com/transcript.jsp?pid=23525 -------------------------------------------------- Moving to Linux is more evolution than revolution.

↪ replying to Francisco Huezo
smooth1 — — source: Informix-list mailing list archive (1991-1998)

Yes although they are undocumented. Check the FAQ at www.smooth1.demon.co.uk I have recently added the script which Art mentions to the FAQ! Francisco Huezo wrote in message <8r2v3m$r79$1@news.xmission.com>... > >Art. > >I only have one question more. >These parameters apply to IDS 7.31 > > >El Fri, 29 Sep 2000, Art S. Kagel escribi': >> Francisco Huezo wrote: >> > >> > Hi. >> > >> > The true is these couple of parameter are new for me. >> > DD_HASHSIZE and DD_HASHMAX.>> >> > I looked up the Administrator's and Performace guide for IDS 7.31 >> > and i can't find anything about them. >> > >> > In the forum, I learned something but i think is not enough, so far I guess >> > they allow tunning the dicctionary cache and these parameter I have to add into >> > onconfig file. >> >> Correct. They are mostly undocumented. See my chapter in the Informix >> Handbook for others. >> >> > But, what are the correct values that they will have? >> > How do I know if the server is correctly tunning? >> >> The value of DD_HASHSIZE must be a prime number and DD_HASHMAX a >> smallish integer. The former is the number of hash buckets the latter >> the number of slots in each bucket. The product of the two is the >> maximum number of tables the dictionary hash table will hold but >> hashing realities makes the actual count somewhat less. Someone posted >> a script that purports to approximate the tablename hash that the >> engine uses to assign tables to buckets so you can calculate a good >> DD_HASHMAX for a given DD_HASHSIZE and play with different values of >> the latter. >> >> Art S. Kagel >> >> >> > Could somebody explain them to me or where can I find a information. >> > >> > Thank a lot for your advices. >> > >> > -- >> > Francisco Huezo >> > Administrador de Base de Datos >> > Ministerio de Hacienda >> > Proyecto SAFI >> > Cond. Tres Torres, T-2, N-8 >> > San Salvador, El Salvador >> > Tel. (503) 225-3700 ext 102 >> > Cel: (503) 830-7469 >> > ------------------------------------------------- >> > Brainbench Certified >> > Power Builder 6.0 >> > Informix DBA >> > Unix Administration ( General ) >> > http://www.brainbench.com/transcript.jsp?pid=23525 >> > -------------------------------------------------- >> > Moving to Linux is more evolution than revolution. >-- >Francisco Huezo >Administrador de Base de Datos >Ministerio de Hacienda >Proyecto SAFI >Cond. Tres Torres, T-2, N-8 >San Salvador, El Salvador >Tel. (503) 225-3700 ext 102 >Cel: (503) 830-7469 >------------------------------------------------- >Brainbench Certified >Power Builder 6.0 >Informix DBA >Unix Administration ( General ) >http://www.brainbench.com/transcript.jsp?pid=23525 >-------------------------------------------------- >Moving to Linux is more evolution than revolution.

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