Mysql – Migration from DB2 to MySQL

I think that simplest way is to use that --hex-blob switch on mysqldump and restore by psql, with decode(string text, type text). However it's not that simple, because you need to change a little produced dump (sed, awk), adding that decode function. For example:

mysqldump -u root -p --skip-quote-names --hex-blob --skip-triggers \
    --compact --no-create-info mysql samples > prepg.dump

sed "s/0x\([0-9,A-F]*\))/decode('\1','hex'))/g" prepg.dump > pg.dump

psql session:

CREATE TABLE samples
(
    file_id integer PRIMARY KEY,
    file bytea
);

\i 'path/to/pg.dump'

You need to take the data from UTF-8 and convert it into UCS-2LE using something like iconv. For example, using the character in your example:

echo "010000: dcb3" | xxd -r -s -0x10000 | iconv -f "UTF-8" -t "UCS-2LE" | xxd
0000000: 3307 

Now I'm not sure what character UTF-8 \xdcb3 is, but apparently it's correct translation to UCS-2LE is \U0733. If you have \0xDCB3 in the SQL Server it means it was not translated into UCS-2LE before import. You should not have surrogates in the NVARCHAR fields, UCS-2 is "surrogate agnostic". See UCS-2 vs. UTF-16 (not quite Kramer vs. Kramer).

I'm not an expert in the MySQL tool set so I can't say what step is missing that was supposed to do the iconv.

Update

to locate the records with surrogates you must turn to the binary representation, since any character function will threat the surrogates as 'special':. Luckily the string manipulation functions work on binary too with the expected semantics. Eg. CHARINDEX:

insert into test(a) values  (N'a');
insert into test(a) values  (NCHAR(0xdc83));
insert into test(a) values  (N'b');
go

select * from test where charindex(0x83dc, cast(a as varbinary(8000))) > 0;