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From "Knut Anders Hatlen (JIRA)" <derby-...@db.apache.org>
Subject [jira] Commented: (DERBY-1473) Add cut-off and truncation logic to streaming classes in the embedded driver
Date Tue, 15 Aug 2006 07:33:16 GMT
    [ http://issues.apache.org/jira/browse/DERBY-1473?page=comments#action_12428053 ] 
            
Knut Anders Hatlen commented on DERBY-1473:
-------------------------------------------

I have started reviewing the patch. I haven't finished the review yet,
but I'll post the comments I have so far.

- CharAlphabet.java contains some UTF-8 encoded characters, and I had
  to change my locale to be able to compile it. These characters
  should probably be escaped.

- RawToBinaryFormatStream(InputStream, int) first checks whether
  length is less than zero, and throws an exception if it is. After
  that check, there's a new one "if (length >= 0) {...} else {...}",
  but at that time length is guaranteed to be greater than or equal to
  zero.

- RawToBinaryFormatStream and ReaderToUTF8Stream sometimes throw
  IllegalArgumentException. I not sure whether I think this is a good
  or a bad approach. I think it is good because internal errors in
  Derby will be exposed and can be fixed. I also think it not so good
  because the conditions that are checked are not critical, and it
  would make sense to carry on in insane mode (for instance, typeName
  == null won't be a problem until an error message using the type
  name is constructed, and maximumLength < 0 will be treated more or
  less as 0). I think either it should be rewritten using
  SanityManager.ASSERT, or it should have a comment saying why
  IllegalArgumentException is used and that it won't be exposed to the
  users unless there's a programming error in Derby.

- In RawToBinaryFormatStream.checkSufficientData(), the body of the
  "if (c != -1)" clause has become very large. I think it would be
  clearer if it had braces around it (although the diff would be three
  lines longer).

Thanks.

> Add cut-off and truncation logic to streaming classes in the embedded driver
> ----------------------------------------------------------------------------
>
>                 Key: DERBY-1473
>                 URL: http://issues.apache.org/jira/browse/DERBY-1473
>             Project: Derby
>          Issue Type: Improvement
>          Components: JDBC
>    Affects Versions: 10.2.0.0
>            Reporter: Kristian Waagan
>         Assigned To: Kristian Waagan
>             Fix For: 10.2.0.0
>
>         Attachments: derby-1473-1a-streaming.diff, derby-1473-1a-streaming.stat, derby-1473-2a-streamingtests.diff,
derby-1473-2a-streamingtests.stat
>
>
> When streaming data to Derby, the application stream will be wrapped in a Derby-specific
stream to convert the data to the correct representation. At a minimum, this consists of getting
the data to the on-disk format used by Derby.
> The wrapping stream can be extended to provide the following features at an earlier stage:
>  a) Data cut-off when the maximum allowed size is exceeded
>  b) Truncation of trailing blanks where allowed
> Both features can reduce the amount of data needed to be kept in memory on insertion.
> Implementing this will require additional column/data type information in the streaming
class(es). The implementation must be able to handle streams for which the length is specified
and also streams with unknown/unspecified length.

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