Org-mode: clarify the concept and practice of archiving

Question

My current org file (e.g. work.org) has 20+ DONE tasks and Org-mode becomes extremely slow: even moving the cursor takes a 2-3 seconds sometimes. I decide I have to archive these DONE tasks, but I found I don't know what Org-mode is actually doing to my text when archiving.

There are a few common options to archive:

1. archive subtree using the default command C-c C-x C-a It moves my subtree (a DONE task) from work.org to work.org_archive
2. move subtree to archive file C-c C-x C-s It also moves my subtree from work.org_archive
3. toggle ARCHIVE tag / to ARCHIVE sibling C-c C-x a/A It greys out my subtree (the DONE task) but the task remains visible on work.org when I expand the top tree. However, details of the subtree is not expandable, unless I do "force cycling of an ARCHIVEd tree" (C-TAB)

My questions are: If I archive using #3, does the content of completed tasks stay in work.org? And does #3 offer already significantly performance improvement over a large Org file?

Also, if I archive using #1 or #2, how can I: Search the archived contents on separate files? Do I just include the :archive: only? Or do I need to list and include all these files in my .emacs under org-agenda-text-search-extra-files?

And how do I refile a subtree by C-c C-w? Is it similar to refiling in other case: i.e. find the subtree in search by other ways, do a C-c C-w to move the subtree to the section I want, and then just save both the target org file and the .org_archive file in question. Is there other things I have to pay attention to?

My Emacs (25.1 64-bit in Windows10) just crashed... Emacs (esp. Org mode) has become so slow and almost inoperable that typing on Firefox is quicker.

Answer 1

It seems Org-mode's archiving function is not popular. Here's what I found:

By using toggle ARCHIVE tag / to ARCHIVE sibling C-c C-x a/A, the content of completed tasks stay in work.org. It seems to me it does not offer significantly performance improvement over a large Org file - if the chunk you have to archive is really large.

One can search archived contents on those separate files (in my case .org_archive files) by including them by the variable "org-agenda-text-search-extra-files" so that they are included in search using "C-c a s"

    (setq org-agenda-text-search-extra-files
          (append
           (sa-find-org-file-recursively "~/Dropbox/Org/" ".org_archive") ;agenda-archives
           (sa-find-org-file-recursively "~/Dropbox/Org/journal/" ".txt") ;journals in .txt
     ))

The function "sa-find-org-file-recursively" that recursively look for files in a folder and its sub-folder can be found here: https://stackoverflow.com/questions/11384516/how-to-make-all-org-files-under-a-folder-added-in-agenda-list-automatically

One caveat is that only the "text search" searches only the Org header text of various levels, but nothing in its body text.

Including the :archive: tag may help when an entry is only tagged :archive: but not really archived. However, when an entry is archived it can only be reached during search when its file is included in the "org-agenda-text-search-extra-files" variable.

To refile an archived entry is quite simple, one can open the corresponding archive file (in Org format) and do a C-c C-w at the entry to be refiled.