Thread: Migration: Informix to PostgreSQL Case Study
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Dear all, I am writing my diploma thesis on "Migrating to Open Source Databases" (at Technical University Berlin, Computer Science). For early review, I just finished a draft of my case study on migrating a library administration system from Informix (IDS 9.2) to PostgreSQL. You can download it at http://www.osdbmigration.org/index.php/Papers along with other parts of the thesis, e.g. an Open Source Database Feature Matrix, or the second case study on migrating a data warehouse (the draft also features some evaluation of Bizgres, but slightly out-of-date). Probably this stuff may be of some use for the PostgreSQL technical documentation or anybody planning a migration themselves. I would very much appreciate some comments (most of all: did I get all the facts on PostgreSQL right) and I will be happy to answer questions. Links: Thesis Wiki: http://www.osdbmigration.org Case Study 1: Data Warehouse: http://www.osdbmigration.org/misc/case1_datawarehouse_draft.pdf Case Study 2: Informix 2 PostgreSQL: http://www.osdbmigration.org/misc/case2_inf2pg_draft.pdf Open Source Database Comparison: http://www.osdbmigration.org/index.php/Open_Source_Databases_Feature_Matrix Kind regards, Jutta Horstmann -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.0 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFC/G7sjowk+u8uwgERAnBdAKCkrMoQkog/ssPkkfyHBmzbZAsngQCg9S/f EtcT0T5RVM7ceHi05oduhWQ= =Bjnk -----END PGP SIGNATURE-----
Hi, Just a couple of quick comments. On 3.1.5 you mention companies giving commercial support. It might be a good idea to add there one or two more, just to show that there really are more companies. Which are most relevant in Germany, I don't know. You mention, that there is no multi-processor support in PostgreSQL... If I remember correctly, (and there are many here, who really know this much, much better), in PostgreSQL you cannot bind certain tasks etc. to certain processors, but SMP exists for many different processor architectures. So, you can have for example a 4 processor computer running PostgreSQL. (I don't know what are the biggest setups, but I guess quite much bigger.) Sorry, haven't read the whole story, so no more comments now. Rgs, Jussi Jutta Horstmann wrote: >-----BEGIN PGP SIGNED MESSAGE----- >Hash: SHA1 > >Dear all, > >I am writing my diploma thesis on "Migrating to Open Source Databases" >(at Technical University Berlin, Computer Science). > >For early review, I just finished a draft of my case study on migrating >a library administration system from Informix (IDS 9.2) to PostgreSQL. > >You can download it at http://www.osdbmigration.org/index.php/Papers >along with other parts of the thesis, e.g. an Open Source Database >Feature Matrix, or the second case study on migrating a data warehouse >(the draft also features some evaluation of Bizgres, but slightly >out-of-date). > >Probably this stuff may be of some use for the PostgreSQL technical >documentation or anybody planning a migration themselves. > >I would very much appreciate some comments (most of all: did I get all >the facts on PostgreSQL right) and I will be happy to answer questions. > > >Links: >Thesis Wiki: http://www.osdbmigration.org >Case Study 1: Data Warehouse: >http://www.osdbmigration.org/misc/case1_datawarehouse_draft.pdf >Case Study 2: Informix 2 PostgreSQL: >http://www.osdbmigration.org/misc/case2_inf2pg_draft.pdf >Open Source Database Comparison: >http://www.osdbmigration.org/index.php/Open_Source_Databases_Feature_Matrix > >Kind regards, >Jutta Horstmann >-----BEGIN PGP SIGNATURE----- >Version: GnuPG v1.4.0 (GNU/Linux) >Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org > >iD8DBQFC/G7sjowk+u8uwgERAnBdAKCkrMoQkog/ssPkkfyHBmzbZAsngQCg9S/f >EtcT0T5RVM7ceHi05oduhWQ= >=Bjnk >-----END PGP SIGNATURE----- > >---------------------------(end of broadcast)--------------------------- >TIP 3: Have you checked our extensive FAQ? > > http://www.postgresql.org/docs/faq > > >
Jutta Horstmann wrote: > I would very much appreciate some comments (most of all: did I get all > the facts on PostgreSQL right) and I will be happy to answer questions. Just one note: You say that postgres has no multi-processor support. I think this is rather missleading and not true for most situations. While it's correct that postgres cannot make use for more than one processor for a single query/connection, for multiple connections it will happily run on as much cpus you give it. At least for typical OLTP use, postgres has multi-processor support. Best Regards, Michael Paesold
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Michael Paesold wrote: > Just one note: You say that postgres has no multi-processor support. I > think this is rather missleading and not true for most situations. > While it's correct that postgres cannot make use for more than one > processor for a single query/connection, for multiple connections it > will happily run on as much cpus you give it. Dear Jussi, Dear Michael, thanks for your comments. You are both referring to the main draft paper, the chapter on PostgreSQL features, I suppose. You are right, I have to correct the statement on multi-processor support. I put it better, I hope, in the Informix migration case study (p.18): "The SUN server uses two SPARC processors. PostgreSQL will make use of both when separate connections are running in parallel. The DBMS is not able to spread one connection?s query over both CPUs." Regards, Jutta -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.0 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFC/H30jowk+u8uwgERAjQXAKDwz7IAPP6XvpKxDbU1w5oEHr9i5QCgniFK XcWPOUhd6czTVJLmzF6O0u4= =+KT2 -----END PGP SIGNATURE-----
Jutta wrote: > Dear all, > > I am writing my diploma thesis on "Migrating to Open Source Databases" > (at Technical University Berlin, Computer Science). > > For early review, I just finished a draft of my case study on migrating > a library administration system from Informix (IDS 9.2) to PostgreSQL. > > You can download it at http://www.osdbmigration.org/index.php/Papers > along with other parts of the thesis, e.g. an Open Source Database > Feature Matrix, or the second case study on migrating a data warehouse > (the draft also features some evaluation of Bizgres, but slightly > out-of-date). > > Probably this stuff may be of some use for the PostgreSQL technical > documentation or anybody planning a migration themselves. > > I would very much appreciate some comments (most of all: did I get all > the facts on PostgreSQL right) and I will be happy to answer questions. Very excellent paper and thank you! One small correction: the PostgreSQL char(n) type takes n bytes, where n is the maximum size of the string. Varchar takes m + 4 for each row, where m is the actual string length (space delimited). Also, it would be nice (IMO) to have more qualitative assessments: Was the project a success? If so, what factors contributed and what didn't? Why was the project considered in the first place? Also, the 'intangibles': What fears did the developers have? The administration? What is the impression of the project by the users? Merlin
On Fri, Aug 12, 2005 at 08:22:39AM -0400, Merlin Moncure wrote: > One small correction: the PostgreSQL char(n) type takes n bytes, where n > is the maximum size of the string. Varchar takes m + 4 for each row, > where m is the actual string length (space delimited). Not quite true -- char(n) also takes n+4, but only in single byte encodings. It can take more -- AFAIU it can be up to n*4 + 4 (worst case) in UTF8. -- Alvaro Herrera (<alvherre[a]alvh.no-ip.org>) "Et put se mouve" (Galileo Galilei)