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From Stanley Bradbury <Stan.Bradb...@gmail.com>
Subject Re: updatable ResultSet: inserted row "may" become visible?
Date Wed, 24 Oct 2007 01:41:17 GMT
Michelle Caisse wrote:
> The Derby Developer's Guide states:
>
>    Rows inserted to the table may become visible in the result set. 
> (p. 57)
>
>    If the inserted row satisfies the query predicate, it may become
>    visible in the result set. (p. 58)
>
> What does "may" mean? Are there no circumstances in which the insert 
> is guaranteed to become visible in the result set?
>
> -- Michelle
>
Hi -
I think I found the passage you refer to but it is not on pg 57 in the 
10.3 Developers guide I looked at.  Please indicate the version of the 
manuals or better yet, the section of the document.  I found the text  
you mentioned in the section "Updatable result sets".

I believe whether the row becomes visible depends on how many rows are 
cached at the time the insert is performed.  If the entire ResultSet is 
already cached you will not see the inserted row because Derby will not 
do another read from disk.  If, however, you are stepping down through a 
large ResultSet where all the records have not been read and the 
inserted record sorts below the current position the new record could be 
read from the disk when it is reached. 

I don't believe there is anyway to predict this behavior.


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