[jira] Commented: (JCR-1166) JCR2SPI does not provide actual size on RangeIterator.getSize()

["angela (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/JCR-1166?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12544864 ] 

angela commented on JCR-1166:
-----------------------------

i would suggest modify the LazyItemIterator to apply the same logic as present currently in the query.NodeIteratorImpl:

- take the size of original collection as estimation for the number of Items available during iteration.
- recalculated the size if entries that cannot be resolved to Items are found during the iteration.

this would have the following benefits:
- if nothing changes in the meantime the size estimate is accurate
- no extra effort to calculate the size upon/before creating the iterator
- don't modify lazy behaviour of the iterator

drawback:
- size may shrink during iteration.


> JCR2SPI does not provide actual size on RangeIterator.getSize()
> ---------------------------------------------------------------
>
>                 Key: JCR-1166
>                 URL: https://issues.apache.org/jira/browse/JCR-1166
>             Project: Jackrabbit
>          Issue Type: Improvement
>          Components: jackrabbit-jcr2spi
>            Reporter: Julian Reschke
>            Priority: Minor
>
> Currently, JCR2SPI always returns -1 on RangeIterator.getSize().
> This return value is legal (meaning "unknown"), but may cause clients to simply iterate through the whole list when what they really want is simply the count.
> Use case:
> "The use case is to count the number of members of a NT_FOLDER without having to open up the NT_FOLDER and count all the members (and I assume load them into memory) "
> To make this happen we probably need to move away from simple Iterators on the SPI level, and put quite some additional work into JCR2SPI.
> Feedback appreciated.

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