[
https://issues.apache.org/jira/browse/DERBY-4544?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12833823#action_12833823
]
Kristian Waagan commented on DERBY-4544:
----------------------------------------
One of the messages one might see due to this error:
Caused by: java.sql.SQLException: Java exception: 'ASSERT FAILED Less than one
byte per char, characterstreambui...@31380681:bufferable=false,
isPositionAware=false, curBytePos=0, curCharPos=0, dataOffset=2,
byteLength=24932, charLength=65534, maxCharLength=9223372036854775807,
stream=class org.apache.derby.iapi.services.io.FormatIdInputStream:
org.apache.derby.shared.common.sanity.AssertFailure'.
In insane builds YMMV, depending on the contents of the value you insert. You
may get an IOException when you read back the value, or you can get wrong
results.
Here's an example where 65536 chars have been inserted as a stream:
id=4, clen=65536, length(myclob)=65534, String(myclob).length()=24930
clen is the generated column, length(myclob) is obtained after the insert as
select length(myclob), and the last number is obtained as
rs.getString(1).length().
> Referencing streaming CLOBs in (some) generated column clauses fails
> --------------------------------------------------------------------
>
> Key: DERBY-4544
> URL: https://issues.apache.org/jira/browse/DERBY-4544
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.5.3.0, 10.6.0.0
> Reporter: Kristian Waagan
>
> Referencing a CLOB represented as a stream in generated columns can lead to
> data corruption or that the query fails.
> For instance, with 10.5:
> create table t (id int, myclob clob, clen generated always as
> (length(myclob)));
> # Insert CLOB using the streaming APIs (setCharacterStream).
> The exception 'java.lang.ClassCastException:
> org.apache.derby.iapi.types.ReaderToUTF8Stream cannot be cast to
> org.apache.derby.iapi.types.Resetable'
> On trunk the same query results in data corruption, and this isn't detected
> before the value is read back from store.
> Workaround:
> Don't use the streaming APIs when using CLOBs in generated columns. This
> increases the memory footprint, and may not feasible for large CLOBs.
> FYI, BLOB deals with this by materializing the value, which effectively
> equals to using the workaround mentioned above.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
