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From mike matrigali <mikema...@gmail.com>
Subject Re: Need some help in trying to figure out a corrupt database
Date Fri, 05 Aug 2016 14:34:20 GMT
I agree with bryan's first suggestions, more info from derby.log would help.  If it is possible
just posting
it currently might help (one from debug with line numbers even better). i would suggest filing
and posting info and moving discussion there.

Some other questions/suggestions.
o can you tell us more about the ddl, i have not used describe much.  What i am looking mostly
for is if there are any unique keys.
o what exactly are the indexes that you have on this table?  what i am looking for is what
columns are in the indexes.
o look at the query plans for the queries that you are running, both the ones that are working
and the
    ones that are not.   what i am looking for is if the optmizer has been able to run some
queries as "covering" which means it gets
    all the values from the index and never goes to the base table.
o if indexes are being used you might try using the optimizer hints to force index or force
not index to better understand where
    corruption is.

on the ordering question, it depends on the answers to the above.   If indexes are used the
ordering is going to be different
for each.   A base table scan should theoretically give same order for each scan as long as
there is no updates happening.

does anyone know if describe prints the columns in the order they are actually stored in the

if you have unique keys and the indexes are good, there may be some ways to better get at
the data.


On 7/27/2016 7:16 AM, Bergquist, Brett wrote:
> I wrote a tool to call SYSCS_UTIL.SYSCS_CHECK_TABLE on each table in the database and
not just stop on error.
> I have a database returns the error:
>         Checking CORE_V1.DEVICE_ENTITY failed with exception: Restore of a serializable
or SQLData object of class , attempted to read more data than was originally stored
> The table has 1261157 rows in it.   I can query each of the columns in the table individually
>          ...
> These all return 1261157 rows for each select result.
> If I select multiple columns such as
> Then I get:
> ERROR XSDA7: Restore of a serializable or SQLData object of class , attempted to read
more data than was originally stored
> ERROR XJ001: Java exception: ': java.io.EOFException'.
> ij>
> The table schema looks like:
> ij>  describe core_v1.device_entity;
> ------------------------------------------------------------------------------
> DTYPE               |VARCHAR  |NULL|NULL|64    |NULL      |128       |YES
> OPLOCK              |INTEGER  |0   |10  |10    |0         |NULL      |NO
> RELATIVE_POSITION   |SMALLINT |0   |10  |5     |NULL      |NULL      |YES
> ALIAS_NAME          |VARCHAR  |NULL|NULL|255   |NULL      |510       |YES
> DESCRIPTION         |VARCHAR  |NULL|NULL|255   |NULL      |510       |YES
> DEVICE_NAME         |VARCHAR  |NULL|NULL|255   |NULL      |510       |YES
> PARENTENTITY_ID     |INTEGER  |0   |10  |10    |NULL      |NULL      |YES
> ID                  |INTEGER  |0   |10  |10    |NULL      |NULL      |NO
> 8 rows selected
> I am trying to figure out how to recover and correct this table.   Once thought is to
query each column separately and then join the output externally back together and re-import
the data.   I wonder however if I query each column if the order of the rows returned will
be the same.  This will be necessary because I cannot select the ID with the other column
to identify the rows.
> Any thoughts will be most welcome.
> Canoga Perkins
> 20600 Prairie Street
> Chatsworth, CA 91311
> (818) 718-6300
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email:    Mike Matrigali - mikemapp1@gmail.com
linkedin: https://www.linkedin.com/in/MikeMatrigali

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