Maybe the DB need run
delete from dns_records_0_1 where savedate not in (select min(savedate) from dns_records_0_1 group by dns,host)
I mean save dissent host&dns (a host changed IP, it should be recorded)
Thanks for reviewing. The addon is supposed to keep all the DNS records, especially the history. I wonder if you want to minimize the sqlite file?
I have checked some websites with F12 key of firefox - Network -> Timings and see that all DNS ms times were gone for some websites, so I see the advantage of this addon.
The DNS prefetching is handled by Firefox (https://developer.mozilla.org/en-US/docs/Web/HTTP/Controlling_DNS_prefetching). This addon saves the DNS records in the local database, but doesn't make usage of it, to perform optimization or else.
I was and am still not so sure about how to make usage of the saved DNS records. Besides I haven't figured out a way to use the saved DNS to 'hijack' Firefox's DNS lookup. For example, in case a 'xxx.com' isn't in the Firefox DNS cache, and there's a record in this addon's database 'xxx.com' - 220.127.116.11, I don't know how to tell Firefox to use 18.104.22.168 for it.
One way to override DNS is through host file, like https://addons.mozilla.org/en-US/firefox/addon/switchhosts/
Anyways, I'll be happy to see other addons (editors, convertors) taking advantage of the saved records, before I know how to.