Due to the change from id to UUID I guess it is nearly impossible (aka too 
complex) attempt a sql reverse migration and for sure it is not something that 
can be done automatically.
One option could be to extract the AIP from DSpace 6.2 and reimport such AIP in 
a fresh DSpace 5.8. Please note that in this way you will loss some 
information, at least:
- inprogress submission
- withdrawn items
- statistics
such information could be recovered with custom ETL but it requires expert 
skills.
A DSpace-CRIS 6 version exists, as for DSpace (this is my personal opinion), it 
is no so stable as the version 5
Andrea


Il 22/03/2018 14:11, helix84 ha scritto:
On Thu, Mar 22, 2018 at 1:49 PM, 
<[email protected]<mailto:[email protected]>> wrote:
Is there a possibility to downgrade Dspace 6.2 to Dspace-CRIS 5.8.1 ?

It would definitely be a completely or partially manual process. You can see 
the upgrade migrations for postgres here:

https://github.com/DSpace/DSpace/tree/master/dspace-api/src/main/resources/org/dspace/storage/rdbms/sqlmigration/postgres<https://urlsand.esvalabs.com/?u=https%3A%2F%2Fgithub.com%2FDSpace%2FDSpace%2Ftree%2Fmaster%2Fdspace-api%2Fsrc%2Fmain%2Fresources%2Forg%2Fdspace%2Fstorage%2Frdbms%2Fsqlmigration%2Fpostgres&e=3bf0957c&h=19dc56d3&f=n&p=y>

To downgrade, you would need to apply them "in reverse".

Of course, if there are any destructive operations, there's no way to 
automatically reverse those. There's such an operation in the very first 
migration: DROP VIEW community2item; You would need to find CREATE VIEW 
community2item in one of the previous migrations (in this example, it's in 
V1.1__Initial_DSpace_1.1_database_schema.sql).

I checked whether Flyway, the DB migration engine DSpace uses, supports 
downgrades. It seems it does, subject to the limitations I mentioned. I haven't 
tried it though and they mention it's available only in their Pro edition which 
I don't have any experience with. In any case, the Flyway route would only be a 
partial automation of the process.

https://flywaydb.org/documentation/faq#downgrade<https://urlsand.esvalabs.com/?u=https%3A%2F%2Fflywaydb.org%2Fdocumentation%2Ffaq%23downgrade&e=3bf0957c&h=eb8f0329&f=n&p=y>

Should you manage to downgrade the database successfully, you would continue as 
per normal DSpace 5 installation instructions. Then you would follow the 
DSpace-CRIS 5 installation instructions.



Regards,
~~helix84

Compulsory reading: DSpace Mailing List Etiquette
https://wiki.duraspace.org/display/DSPACE/Mailing+List+Etiquette<https://urlsand.esvalabs.com/?u=https%3A%2F%2Fwiki.duraspace.org%2Fdisplay%2FDSPACE%2FMailing%2BList%2BEtiquette&e=3bf0957c&h=0b39f48d&f=n&p=y>

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