Re: [ovirt-users] upgrade to 4.1

On Thu, Apr 20, 2017 at 6:59 PM, Simone Tiraboschi <stirabos(a)redhat.com&gt; wrote: Is there a good reason to not have them exactly equal? The main reason we require this is for pg_dump/pg_restore which are ran during setup/rollback (if needed). pg_dump can't know for sure that all the changes in the db were done using a client of its own version (that is, current machine usually), and if indeed a newer client was used, it might have used features that pg_dump of the lower version doesn't know how to back up (and especially pg_restore does not know how to restore). See also [1]. I seem to have tested there (can't remember anymore, see comment 13) 9.2 client with 9.5 server and it didn't work. pg_dump(1) manpage says: Because pg_dump is used to transfer data to newer versions of PostgreSQL, the output of pg_dump can be expected to load into PostgreSQL server versions newer than pg_dump's version. pg_dump can also dump from PostgreSQL servers older than its own version. (Currently, servers back to version 7.0 are supported.) However, pg_dump cannot dump from PostgreSQL servers newer than its own major version; it will refuse to even try, rather than risk making an invalid dump. Also, it is not guaranteed that pg_dump's output can be loaded into a server of an older major version — not even if the dump was taken from a server of that version. Loading a dump file into an older server may require manual editing of the dump file to remove syntax not understood by the older server. Use of the --quote-all-identifiers option is recommended in cross-version cases, as it can prevent problems arising from varying reserved-word lists in different PostgreSQL versions. So personally I'd keep things as they are, unless someone can present a good reason to do a more delicate test. If someone indeed wants that, please: 1. Open a bz and state what you want (make backup optional, use some other less strict test on version numbers, something else?). 2. If you want more delicate tests, please verify that what you ask for indeed works, and provide details. E.g., try this: * setup an engine with 9.4.8 client and server (can be on same machine) * pg_dump this engine's db with 9.4.8 to dump1 * pg_restore dump1 to a 9.4.11 server. Did this work? * use pg_dump 9.4.8 to dump the db from the 9.4.11 server to dump2. Did this work? * use pg_restore 9.4.8 to restore dump2 to the 9.4.11 server. Did this work? * Compare dump1 and dump2. What are the differences? It might make sense to do similar tests with the opposite - client is newer than server. Also with "more far away" versions (say 9.4 and 9.5). Also perhaps other tests, especially if you manage to find new features in 9.4.11 compared to 9.4.8 (hopefully there aren't any) and in 9.5 compared to 9.4. [1] https://bugzilla.redhat.com/1331168 This isn't a new test, see above bug. Are you sure it's the first time you see it? Perhaps you upgraded your pg server only after the last upgrade of the engine? Best, -- Didi