我正在从 Kunena 进行迁移，目前已完成一半。我（几乎）成功运行了一次测试迁移，但考虑到永久链接问题和内部链接问题，我不禁想到……
让 Discourse 在创建新帖子时保留 Kunena 最初分配的旧帖子 ID，这会很困难吗？这种方法有明显的优势。
我猜这将涉及：
对导入脚本进行一些调整。有人能估计一下这种更改的“深度”吗？帖子 ID 是在 Discourse 代码的非常深层被分配的，还是在基础导入脚本中的某个位置？
某种防止 Discourse 将已使用的帖子 ID 分配给未来新帖子的方法。我们是否有地方可以配置 Discourse，使其从例如 100,000 开始分配帖子 ID？
帖子 ID 可以是非数字的吗？如果可以，我在想像“k12345”（用于来自 Kunena 的内容）这样的格式可能是一个不错的折中方案。我可以保留一种引用旧帖子 ID 的方式，但它们不会与 Discourse 分配的新 ID 冲突。
提前感谢任何提示！
The import script saves the import id in a post custom field. You can use it to create permalinks. Several importers do that. You can look at others for examples.
Thanks Jay, I know that, and I use that to go from old ids to new ids.
But it would be more practical to simply use the same number and avoid that de-referencing. I am doing parts of my import with SQL and it complicates queries.
Also, the permalinks table can get quite huge. A regexp redirect is better, and easy if the id is constant.
The permalinks table is only as big as the post table. You know about permalink normalizations?
But to answer your question, yes, having discourse use different topic id would be very hard.
It seems Discourse relies on PostgreSQL to assign the id, which is numeric:
And it seems PostgreSQL allows manipulation of that “sequence object”:
https://www.postgresql.org/docs/8.3/static/functions-sequence.html
So I guess my number 2 is answered “yes” and my number 3 is answered “no”. My question number 1 is probably what you mean by “very hard”, right? 
EDIT: let me just add that posts uses the same mechanism as topics
I had heard about these regexp operations but I was thinking they required post ids to match so a simple find-and-replace could take me from the old post id to the new one.
Or is the mechanism more intelligent and it does a lookup on the post custom field to translate ids?
Yes. You still need to have the post (or topic or category) ID in a permalink.
Your solution might work with a plugin that you would have to continually maintain, but it’ll be really hard, and the recommended way works and has been used dozens of times, including several with millions of posts, and that’s just me.
The approach (without keeping a plug in all the time) could be:
But ok, I get the point - it’s easier with the permalinks feature. I have found many posts with specific questions about this, mostly people trying to get their regexps right, but I haven’t found any page documenting the actual mechanism in general… is there such a page?
As always, thanks a lot for your help.
Can anybody point to any Documentation on how to use the permalinks feature? Even if it’s minimal docs. I don’t mind helping to write a more extended documentation once I understand how this works. Thanks.
The best thing to do is to grep Permalink script/import-scripts/*rb and look at how people have used it.