Show 49 quoted lines
> On Tue, Jun 25, 2019 at 7:40 PM Derrick Stolee <stolee@gmail.com> wrote:
>>
>> On 6/25/2019 6:29 AM, Duy Nguyen wrote:
>>> On Tue, Jun 25, 2019 at 3:06 AM Jeff Hostetler <git@jeffhostetler.com> wrote:
>>>> I'm curious how big these EWAHs will be in practice and
>>>> how useful an array of integers will be (especially as the
>>>> pretty format will be one integer per line). Perhaps it
>>>> would helpful to have an extended example in one of the
>>>> tests.
>>>
>>> It's one integer per updated entry. So if you have a giant index and
>>> updated every single one of them, the EWAH bitmap contains that many
>>> integers.
>>>
>>> If it was easy to just merge these bitmaps back to the entry (e.g. in
>>> this example, add "replaced": true to entry zero) I would have done
>>> it. But we dump as we stream and it's already too late to do it.
>>>
>>>> Would it be better to have the caller of ewah_each_bit()
>>>> build a hex or bit string in a strbuf and then write it
>>>> as a single string?
>>>
>>> I don't think the current EWAH representation is easy to read in the
>>> first place. You'll probably have to run through some script to update
>>> the main entries part and will have a much better view, but that's
>>> pretty quick. If it's for scripts, then it's probably best to keep as
>>> an array of integers, not a string. Less post processing.
>>
>> I don't think the intent is to dump the EWAH directly, but instead to
>> dump a string of the uncompressed bitmap. Something like:
>>
>> "delete_bitmap" : "01101101101"
>>
>> instead of
>>
>> "delete_bitmap" : [ 0, 1, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1 ]
>
> I get this part. But the numbers in the array were the position of the
> set bits. It's not showing just the actual bit map.
>
> The same bitmap would be currently displayed as
>
> "delete_bitmap": [ 1, 2, 4, 5, 7, 8, 9, 11 ]
>
> And that maps back to the entry[1], entry[2], entry[4]... in the index
> being deleted from the base index. So displaying as a real bit map
> actually adds more work for both the reader and the tool because you
> have to calculate the position either way. And it gets harder if the
> bit you're intereted in is on the far right.