Hi Steve,
yes, after x millions of records, it would be nice to have the checksum
taking minimal space.
I've some code making this happen in jruby (it was not easy to convert into
byte array as I'm using prepared statements for initial insertions).
Comparing now performance and size.
Thanks
Christian
On Friday, April 20, 2012 12:54:39 PM UTC+2, Steve McLeod wrote:
>
> Hi Christian,
>
> Is disk space/database size really a concern for your application? If not,
> just storing in a varchar(64) makes your code simple.
>
>
> On Thursday, 19 April 2012 18:50:29 UTC+2, Christian MICHON wrote:
>>
>> Ah... got it: SHA256 is equivalent to ruby's sha2, and not sha256 from
>> openssl (this was completely wrong).
>>
>> In ruby:
>> >> require 'digest/sha2'
>> => true
>> >> Digest::SHA2.hexdigest 'sha256'
>> => "5d5b09f6dcb2d53a5fffc60c4ac0d55fabdf556069d6631545f42aa6e3500f2e"
>>
>> In H2:
>> CALL HASH('SHA256', STRINGTOUTF8('sha256'), 1);
>> gives:
>> X'5d5b09f6dcb2d53a5fffc60c4ac0d55fabdf556069d6631545f42aa6e3500f2e'
>> 5d5b09f6dcb2d53a5fffc60c4ac0d55fabdf556069d6631545f42aa6e3500f2e
>>
>> So we have a match.
>>
>> My 1st question still interests me: how to efficiently store this sha256
>> in H2? Which would be a good data type?
>>
>> Regards,
>> Christian
>>
>> On Thursday, April 19, 2012 6:37:01 PM UTC+2, Christian MICHON wrote:
>>
>>> Yes, I knew about it.
>>>
>>> Yet, this gives me 2 problems:
>>> - increase of 32 char to 64 char for storing the hash. Maybe I should
>>> store this in a different way, like binary to save half the space?
>>> - I cannot figure out how to have the same results between hash() in H2
>>> and sha256 from OpenSSL/ruby
>>>
>>> As said, I use ruby and in ruby OpenSSL::Digest::Digest.new("sha256") ==
>>> "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
>>>
>>> Could you please show me how to get the same value using hash() in H2?
>>>
>>> I tried call hash('SHA256',stringtoutf8('sha256'),1) without success...
>>>
>>> Regards,
>>> Christian
>>>
>>> On Thursday, April 19, 2012 6:04:36 PM UTC+2, Thomas Mueller wrote:
>>>>
>>>> Hi,
>>>>
>>>> H2 supports SHA256 natively, I would use it instead of MD5:
>>>> http://h2database.com/html/functions.html#hash
>>>>
>>>> Regards,
>>>> Thomas
>>>>
>>>>
>>>>
>>>>
>>>> On Saturday, April 14, 2012, Christian MICHON wrote:
>>>>
>>>>> On Friday, April 13, 2012 9:51:52 PM UTC+2, Christian MICHON wrote:
>>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> I need to detect repetitions and updates in (relatively) small H2
>>>>>> tables.
>>>>>>
>>>>>> As such, I currently implemented using ruby and an external ORM a
>>>>>> md5sum calculation of all the keys concatenated into a string following
>>>>>> their natural order, which is stored back into a specific key.
>>>>>>
>>>>>> This involves a lot of communication with the H2 server, and I wish
>>>>>> to have it done natively (using java itself).
>>>>>> (...)
>>>>>>
>>>>>>
>>>>> After many experiments, I finally cracked it.
>>>>>
>>>>> Sharing it here, in case someone else finds this useful one day...
>>>>>
>>>>> CREATE ALIAS MD5 FOR
>>>>> "org.apache.commons.codec.digest.DigestUtils.md5Hex(java.lang.String)";
>>>>> CREATE TABLE TEST(ID IDENTITY, NAME VARCHAR(255), MD5 VARCHAR(32) AS
>>>>> MD5(NAME));
>>>>> INSERT INTO TEST (NAME) VALUES('The quick brown fox jumps over the
>>>>> lazy dog');
>>>>> SELECT * FROM TEST ORDER BY ID;
>>>>>
>>>>> Really powerful tool this H2 db... Congratulations again...
>>>>>
>>>>> Christian
>>>>>
>>>>> --
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>>>>>
>>>>
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