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https://issues.apache.org/jira/browse/OODT-551?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13558185#comment-13558185
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Brian Foster edited comment on OODT-551 at 1/20/13 7:18 AM:
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i'm still against assuming that Metadata maintains add order... it currently
does only because that is a side effect of the currently underlying
implementation... the previous implementation was a hashtable which didn't
preserve order... the Metadata class is not an ordered collection of metadata
fields, but more of a Collection of metadata fields... also adding this to
DataSourceCatalog may work, however how does the LunceneCatalog work for this
type of functionality?... i think if your particular case requires ordering
then make a wrapper layer around Metadata in your code which maintains a
metadata field that is an ordered list of keys... then when you get the
Metadata back you can read that metadata field to get the ordering and just
read the keys in that order.
was (Author: bfoster):
i'm still against assuming that Metadata maintains add order... it
currently does only because that is a side effect of the currently underlying
implementation... the previous implementation was a hashtable which didn't
preserve order... the Metadata class is not an ordered collection of metadata
fields, but more of a Collection of metadata fields... also adding this to
DataSourceCatalog may work, however how does the LunceneCatalog work for this
type of functionality?... i think if your particular case requires ordering
then make a wrapper layer around Metadata in your code which maintains a
metadata field that is an ordered list of keys... they when you get the
Metadata back you can read that metadata field to get the ordering and just
read the keys in that order.
> DataSourceCatalog implementation does not preserve order of metadata values
> ---------------------------------------------------------------------------
>
> Key: OODT-551
> URL: https://issues.apache.org/jira/browse/OODT-551
> Project: OODT
> Issue Type: Bug
> Components: file manager
> Affects Versions: 0.5
> Reporter: Luca Cinquini
> Assignee: Luca Cinquini
> Fix For: 0.6
>
> Attachments: OODT-551.luca.patch.txt
>
>
> The table that stores the metadata (key, value) pairs for the File Manager
> database-based implementation has no primary key - as a consequence, values
> are not guaranteed to be returned in any order, which is a problem for
> applications that rely on the order of the values (for example, among
> different metadata keys).
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