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From "Alex O'Ree" <alexo...@apache.org>
Subject attempting to migrate from postgres to derby
Date Wed, 14 Nov 2018 21:22:04 GMT
Greetings. I'm looking for some kind of migration guide and for things to
watch out for when migration an application to derby.

Since i haven't found one yet, i decide to write down and share some of my
notes on the things I've ran into so far:

DDL - From postgres, there's lots of differences.
- Postgres 'text' becomes 'long varchar'
- Can't insert from 'text literal' into a blob without some quick code and
a function to convert it
- Postgres gives you the option to select the index type, derby does not
appear to. have this function. Not really sure what kind of index it is
either. btree?

JDBC clients
- limit and offset has a bit of a strange syntax. most rdbs will access
just the literal limit 10 offset 1 syntax. Derby appears to need to wrap
this in { }, so select * from table { limit 10 offset 10}
- from a JDBC client, don't include semicolons in your sql code.

For the last two, is this "normal"? I have a large code base and
refactoring it would be painful. I'm thinking it may be easier to hack up
the jdbc driver to "fix" the sql statements on the fly. Any thoughts on
this? maybe there is some kind of configuration setting to make this easier?

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