I'm kicking myself for not taking a screen-capture of my long tag lists! I have some items with a large number of tags. When I try to add yet another one via the "browse item" screen rather than the "edit" screen (i.e. in the right column), it deletes a whole heap cropping it down to about 10 tags. If I go the extra click and add the tag using the "edit" screen, this doesn't happen.
So I've just accidentally deleted a whole bunch of tags for an item and I can't possibly remember all of them. Where are tags for items stored? I regularly backup my database and I'd love to be able to find the tags I used to have on the item!
Tags are managed in two tables: tags and taggings
A tag is the word itself. A tagging is an instance of a user associating a tag with a record (like an item).
What version of Omeka are you using? Are you saying that when you are viewing a particular item in the admin, and you add a tag to the "My Tags" input box which currently contains many tags, and you click "Save Tags", it removes many of the tags?
Can you provide a list of the tags you tried to add?
I'm using version 1.1
And yup - exactly as you said - when I'm viewing an item in the admin and add a tag to "My Tags," hit save, it then truncates the list to around 10 tags.
It's happened to me a few times (I kept forgetting!) when I've tried to add one more tag. If I do it through the "Edit this Item" screen it doesn't happen. It only occurs when there's originally a loooooong list of tags.
Although on a related note, it is annoying that in the "Edit" screen you have to hit "add tags" rather than just saving. A few times I've gone through the "flow" of adding a new item and jumped the gun to hit "save" rather than hitting "add tags" and then "save." And then of course I've forgotten which tags I intended to add!
I successfully added and edited 2000 tags ("1", "2", ... "2000") from the item show page. I was not able to get it to truncate the tags. I'm wondering whether the request is timing out, since it has to process all of that data in the form each time you save it. Also, I wonder if your server has any restrictions on the size of the post data. Perhaps your server is using suhosin or something.
Thanks for looking into it! I'm using Dreamhost. It's not really a big problem, I just have to remember to go to the edit screen instead :)