El día Friday, May 03, 2019 a las 07:38:23AM -0500, Ron escribió:
> On 5/3/19 6:56 AM, Matthias Apitz wrote:
> >Hello,
> >
> >We're investigating the migration of our LMS (Library Managment System)
> >from Sybase ASE 15.7 to PostgreSQL 10.6. The used database in field have
> >around 400 columns, some of them are also containing BLOB (bytea) data.
> >The DB size vary upto 20 GByte. The interfaces contain any kind of
> >language one could imagine :-) ESQL/C, JDBC, Perl DBD, ...
> >
> >Re/ the migration of the data itself, are there any use case studies
> >which could we keep in mind? We plan to export the tables with our own
> >tool which produces CSV with delimiter '|' (and \| if the char | is in
> >char columns too) and with hex representation of the BLOB data. This seems
> >to fit nicely with PostgreSQL's COPY command.
> >
> >Any known pitfalls?
>
> Do you have many stored procedures, functions, etc?
We have in Sybase triggers on some tables calculating the next value for
an integer "serial" based on helper tables because Sybase does not know
(or did not know in 11.9) about serials. But, these will be replaced by native
"serial" on PG.
Sybase also has a so called SYB_IDENTITY_COLUMN in each table with a
unique number for each row (may have gaps) and as Sybase does not know
SCROLLED CURSOR we simulated these in our DB layer reading-in all
SYB_IDENTITY_COLUMN numbers of a hit list after SELECT and can read
backwards in this in memory list presenting the requested row with a new
SELECT based on the SYB_IDENTITY_COLUMN number. This is somewhat
clumsy but certain features in upper layers want to read backwards (and
we came from INFORMIX-SE, later INFORMIX-ONL some 30 years ago).
I was deeply impressed by the COPY command, loading ~35000 rows in the
time one needs to close and open the eyes. As well a SELECT returns in
a table with ~35000 without any INDEX in very short time. How PG does this?
matthias
--
Matthias Apitz, ✉ guru@unixarea.de, http://www.unixarea.de/ +49-176-38902045
Public GnuPG key: http://www.unixarea.de/key.pub
70 years of NATO - 70 years of wars (Jugoslavia, Afghanistan, Syria, ...) and 70 years
of war preparation against Russia. -- PEACE instead of NATO !
