Forgotten line

[tdeo]

Hi,

I was writing some migration on a table, and came across a weird issue while testing in development environment. When I have a single line in a table, this line is lost during the migration process. It works well with 2, 5 or more.

I believe this comes from https://github.com/soundcloud/lhm/blob/master/lib/lhm/chunker.rb#L30.
If I understand that line well, the || (@next_to_insert == 1 && @start == 1) part was added in case @next_to_insert == 0 && @start == 1 && @limit == 1 (if @limit != 1, the second part of the or statement implies the first one).

Shouldn't that line be changed from while @next_to_insert < @limit || (@next_to_insert == 1 && @start == 1) to while @next_to_insert <= @limit?

Moreover, I had a feeling that if @limit - @start % stride == 1, the last line would be lost. I tested that it is actually the case.

[tdeo]

@grobie @sunny Does this issue makes sense and have a chance of being addressed?

I have two PR opened for this:

• Add test to check no line is forgotten when copying 5 lines with stride 2 #134 which adds a test that shows one line gets forgtten
• Fix chunker for forgotten lines #127 which fixes this issue

Should I rebase them?

[grobie]

@tdeo Please go ahead! While I'm not actively using or maintaining LHM anymore, I'd be more than happy to merge a well tested bug fix.