Thread: Calculate reading time.
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Old 12-11-2018, 09:54 PM   #8
davidfor
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Quote:
Originally Posted by chaley View Post
Using the preferences editor changes the last modified date. Try editing the template from the booklist using F2 of any row of the column. IIRC that doesn't change the last modified date.
That was what I was doing when I noticed modified time changing. I was thinking it didn't change, but it did this time.
Quote:
The rationale for changing the last modified date is to be sure that the backup OPF files are up to date. This is a rather complicated question, so the default is "any change requires a new backup".
The only problem with that is that the only time I needed to restore from the backup OPF files, it didn't restore the custom columns. This was for my wife's library and she only had one or two custom columns that didn't have much in them. I've been meaning to look at what went wrong, but I did follow the instructions in https://manual.calibre-ebook.com/faq...libre-is-blank. (OK, I did what I thought should work and then read the manual.) Or have I misunderstood what should happen?

From my point of view, if I add an extra column, then the backup OPF doesn't need to be updated until I populate it with a value. And the library backup status dialog has a button to "Queue all books for backup". Isn't it a matter of triggering that whenever a change is made? Except that it appears to work by changing the modified date for all books (ouch). But, it also appears to work based on the contents of the table "metadata_dirtied". I'm assuming that an entry is added to that table whenever book is modified. Finding another way to populate that after a custom column change, or pressing that button above should do what is desired. I'm sure it won't be as simple as that, but, it will be interesting to see what is needed.

A lot of the frustration with this is that I have been involved in a lot of database migrations and changes over the years. What happens with the the created dates and last modified dates is always something that gets discussed. And frequently we have to do something to prevent them from being changed.
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