almost have a plan

doc/todo/copy-key___40__--batch__41___to_copy__47__merge_availability_info/comment_3_53a7a0d5ba6be411bdae10a6f8ba16fc._comment

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+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 3"""
+ date="2021-05-13T16:10:39Z"
+ content="""
+Hmm, it seems possible that two repos could use the same uuid for a
+remote, but have different configurations for it. Eg, an internal use repo
+that might even embed creds for the remote, and a public use repo that
+relies on public http urls to download from the remote.
+
+So there would then be 3 things that need to be able to be specified:
+
+* keys to copy
+* uuids whose per-key information should be copied (or ones to skip)
+* uuids whose non-per-key information should be copied (or ones to skip)
+  (remote description, special remote config, trust, group, preferred
+  content, etc)
+
+Might as well add, for completeness:
+
+* whether to copy global config settings, or not (numcopies, mincopies,
+  git-annex-config, group-preferred-content, difference.log)
+
+Could get more granular than this, eg only copying some metadata fields and
+not others, or description but not trust log, but I'd want to see a use
+case. A line has to be drawn somewhere or it just gets ridiculous, and the
+user might as well pull up [[internals]] and git-filter-branch and
+post-process the tree generated by this command.
+
+So a UI for these 3 or 4 things..
+
+	git-annex copy-branch --keys-from=path 
+		--include-key-information-for=repo
+		--exclude-key-information-for=repo
+		--include-config-for=repo
+		--exclude-config-for=repo
+		--include-global-config
+		--exclude-global-config
+
+Eg: 
+
+	git-annex copy-branch --keys-from=.
+		--exclude-key-information-for=privateremote
+		--exclude-config-for=privateremote
+		--include-global-config
+"""]]

doc/todo/copy-key___40__--batch__41___to_copy__47__merge_availability_info/comment_4_d82ee205451cf55eb283952c4774d32a._comment

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+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 4"""
+ date="2021-05-13T16:29:41Z"
+ content="""
+The other axis is, I guess, should it include past commits to the git-annex
+branch, or only the current data? I'm inclined toward only the current
+data. The only thing that uses past data really is `git-annex log` and it's just
+not worth the added time expense. And also `git annex forget` already
+throws away the past data.
+
+There is the added wart of exported treeishes being grafted into the
+git-annex branch (to avoid them being lost in GC in some edge cases).
+It would need to do like `git annex forget` was recently fixed to, and
+include those grafts when throwing away the rest of the history.
+(See [[!commit 8e7dc958d20861a91562918e24e071f70d34cf5b]])
+"""]]

doc/todo/copy-key___40__--batch__41___to_copy__47__merge_availability_info/comment_5_3565680846a8d547d0912d1ef31430b2._comment

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+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 5"""
+ date="2021-05-13T16:55:36Z"
+ content="""
+The filtering of uuids from logs this command needs is very closely
+related to how the git-annex branch is filtered when dropping dead uuids
+and keys.
+
+Annex.Branch.Transitions.dropDead could alsmost be used as-is, just
+providing it a trustmap that has the excluded uuids marked as dead.
+
+But, it does not currently modify the trustLog, which makes sense for
+transitions, but for this the trust log needs to include only the desired
+uuids.
+
+And, providing a trustmap does have the problem that,
+if a uuid is mentioned in the branch without being in uuid.log,
+it would not be in the trustmap, and so it would not be excluded. One way
+for that to happen is well, using this command to copy only per-key info
+for a remote, but not config for a remote. Hmm. Using a filtering
+function, rather than a trustmap, would avoid this problem. But,
+dropDead does some processing to handle sameas-uuid pointing to a dead
+uuid, including a special case involving remoteLog.
+
+Implementation plan:
+
+* Address above problems with dropDead, somehow, so it can be reused.
+* Add a function (in Logs) from a key to all possible git-annex branch log
+  files for that key.
+* For each key seeked, run that function, query the branch to see which 
+  log files exist, and pass through dropDead to filter and populate
+  the temporary index. This way, the command does not need to buffer
+  the whole set of keys in memory.
+* Get a list of all non-key logs
+  `(topLevelNewUUIDBasedLogs++topLevelOldUUIDBasedLogs++otherLogs)`,
+  and pass them all through dropDead as well.
+* Refactor regraftexports from Annex.Branch, and call it after
+  constructing the filtered index.
+"""]]