[Webkit-unassigned] [Bug 128444] IDB: storage/indexeddb/mozilla/index-prev-no-duplicate.html fails

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=128444





--- Comment #4 from Brady Eidson <beidson at apple.com>  2014-02-08 10:04:41 PST ---
(In reply to comment #0)
> IDB: storage/indexeddb/mozilla/index-prev-no-duplicate.html fails
...
> - Something else I haven't identified yet.

So say you're walking an index cursor and you get to a lump of 4 record in a row that have the same key.

Those four values are sorted by their referenced value.

In the test case, we see these records in the object store:
        { key: "237-23-7736", value: { name: "Joe", height: 65, weight: 150 } },
        { key: "237-23-7737", value: { name: "Pat", height: 65, weight: 100 } },
        { key: "237-23-7738", value: { name: "Leo", height: 65, weight: 180 } },
        { key: "237-23-7739", value: { name: "Jef", height: 65, weight: 120 } },

The 'height' index has the entries:
        { key: 65, value:  "237-23-7736" },
        { key: 65, value:  "237-23-7737" },
        { key: 65, value:  "237-23-7738" },
        { key: 65, value:  "237-23-7739" },

So when walking the index backwards, you're supposed to first see the record or 7739, then 7738, then 7737, then 7736.

But when walking the index backwards *uniquely*, you're only supposed to see one of the 65 entries.  Which one?

Well, since you get to the 7739 record first (when walking backwards...) I thought it was the 7739 record.
But it turns out when picking which record to return for a unique cursor, you walk to the last record that matches - in this case, the 7736 record.

Yikes.

A new flavor of index cursor statement will fix this.

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