Comment 3 for bug 1639044

On Sat, Nov 5, 2016 at 9:17 AM, Paul Everitt <email address hidden> wrote:

> We will need the ability to the following. For an object at:
>
> /communities/some-community/folders/folderA/folder22/folderB
>
> …to get folder listings for folderB, folder 22, and folderA. With
> filtered query support.
>

The query I gave would give you all of the descendents for any given path.
This makes sense for situations where you use a path search to narrow some
other search to a section of a site.

You can also construct queries to narrow things further, but the index only
helps with the common prefix in a query, so...

> We can do this in another way, simply by adding a column “parent”.
>

If you want *just* the immediate children of an object, then an index on
parent would be better, at least in terms of performance.

The efficacy of solution can only be measured relative to a problem.

>
> We don’t necessarily need to do queries for folderA and get everything
> in folder22 and folderB, if that’s what you mean. But we do need to know
> everything in some-community.
>

See above.

The, to me, weird thing about the ``level`` parameter in PathIndex queries
is that it lets you do things like:

- search for paths that have some subpath (foo/bar) at some level
(``level`` > 0) in the tree.

- search for paths that have some subpath (foo/bar) anywhere in a path.

I suppose some use case motivated this (although I can also imagine an
over-eager generalization :). If it's over-eager generalization, it's a
shame because it made the implementation a lot more complicated and
searches slower.

Jim

>
> —Paul
>
> > On Nov 4, 2016, at 4:35 PM, Jim Fulton <email address hidden> wrote:
> >
> > I had to refresh my memory of what path indexes did. So I looked at:
> >
> > https://docs.zope.org/zope2/zope2book/SearchingZCatalog.html#path-index-
> > record-attributes
> >
> > And then at:
> >
> > https://github.com/zopefoundation/Products.ZCatalog/tree/master/src/
> Products/PluginIndexes/PathIndex
> >
> > /me mops up brain matter
> >
> > Wow, this isn't what I thought I'd remembered.
> >
> > Do, implementing a path index that supports just searching with level =
> > 0 is pretty simple and fast. Just store and btree-index the document
> > paths with trailing delimiters. (eg '/foo/bar/') and do prefix
> > searches:
> >
> > path like '/foo/bar/%'
> >
> > Is this sufficient? Or do you want support for level != 0?
> >
> > --
> > You received this bug notification because you are subscribed to the bug
> > report.
> > https://bugs.launchpad.net/bugs/1639044
> >
> > Title:
> > Explore path-index like queries
> >
> > Status in KARL4:
> > New
> >
> > Bug description:
> > We currently hard-code "community" as a column in our (hacked)
> > pgtextindex. However, we are also going to need to query folder/files
> > in a subfolder. Our current plan was to add another column called
> > "parent" and use it for that case.
> >
> > We could consider solving both with the Zope concept of path index. Do
> > a little research on that. Perhaps it can be encoded directly as an
> > array of docids.
> >
> > To manage notifications about this bug go to:
> > https://bugs.launchpad.net/karl4/+bug/1639044/+subscriptions
>
> --
> You received this bug notification because you are a bug assignee.
> https://bugs.launchpad.net/bugs/1639044
>
> Title:
> Explore path-index like queries
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/karl4/+bug/1639044/+subscriptions
>

--
Jim Fulton
http://jimfulton.info