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Tangled issues with permanent HTTP redirects

by pcr910303 on 9/20/22, 8:15 AM with 14 comments

• by ademarre on 9/23/22, 7:36 AM

  There seems to be some FUD going on here. The solution to the OP problem is simply to use 301 redirects with Cache-Control headers to limit caching to some reasonably short duration.

  It is true that browsers will cache 301 redirects eternally, but only if the server does not supply cache directives to indicate otherwise. For this reason, it is always advisable to include some cache directives in 301 redirect responses, like `Cache-Control: max-age=86400`. I'm surprised that this isn't more universally acknowledged as an important practice.

  As far as search engines, there will not be a problem if a URL that used to return a 301 now returns a 200. The web changes, and search engines know that very well.

  Add: There also seems to be a lot of confusion about the meaning of permanent. Permanent should not be taken to mean eternal. If I move to a new house, I consider that a permanent move, because I no longer live at the old address. But it would be unreasonable to assume that I will never move again. I might even move back to the original house! Such moves are like permanent redirects; I might have my mail forwarded, but it is not an indelible, eternal change. Temporary redirects (302, 303, 307) are more like leaving a sticky note on the door while you're out running an errand; you have not permanently relocated.

• by silverwind on 9/23/22, 6:03 AM

  Permanent redirects are often times just premature optimization. Keep them temporary, preferably 307 to avoid odd browser behaviour with method change.

• by alserio on 9/23/22, 7:19 AM

  Maybe not a good practice but I've recently discovered that caches respect the Cache-Control header even for 301s. This can make 301s not really permanent and give more control on the caching behavior

• by wumpus on 9/23/22, 6:48 AM

  This short essay is good philosophy, but doesn't seem very connected with reality. No, search engines and browsers don't permanently cache permanent redirects. Yes, you should probably use unique usernames instead of reusing them. The second fully mitigates the first, for this particular situation.

• by weird-eye-issue on 9/23/22, 5:32 AM

  If it's not permanent then just keep it temporary... I don't see the problem here