[Libreoffice-bugs] [Bug 133835] Calc autofilter freeze after deselecting an item and pressing OK (number 2)

[bugzilla-daemon at bugs.documentfoundation.org]

https://bugs.documentfoundation.org/show_bug.cgi?id=133835

--- Comment #2 from Kevin Suo <suokunlong at 126.com> ---
I reported bug 136838 before I found this one. Seems a duplicate. I am copy the
following from that bug:

Assume a column contains n items. When we open the autofilter and un-selected
one, then we have n-1 items selected. Doing this filter with AutoFilter is slow
because it seems to be using the "x in n-1" logic. However, doing this filter
with Standard Filter is fast if we use "Not Equal" logic.

Steps to Reproduce:

1. Open the attachment 165612.

2. Click the autofilter in column A, and de-select the 1st item (i.e., #N/A),
then click OK.
--> Slow, it takes more than 8s.

3. Use Standard Filter, and set condition "POMatch <> #N/A", then click OK.
--> Fast, it takes 1s.

Apparently, if we deselect only one item, the condition is the same as <> that
item. It should be more expensive to compare the value to see whether it is in
the n-1 list.

Actually, if we de-select several items (e.g., 3 items), it would still be
faster to use "(x <> a) and (x <> b) and (x <> c)". However, if the deselected
items are quite a lot, the "x in n-1" logic should be faster.

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