X-Git-Url: http://git.vanrenterghem.biz/git.ikiwiki.info.git/blobdiff_plain/15f9bb7ce5034ca9a6c813a0bf7ddb55d73c67fc..7eb512205fba0efad301521bbd641848b4890b1d:/doc/todo/different_search_engine.mdwn?ds=sidebyside

diff --git a/doc/todo/different_search_engine.mdwn b/doc/todo/different_search_engine.mdwn
index 592c159b3..2f309dea5 100644
--- a/doc/todo/different_search_engine.mdwn
+++ b/doc/todo/different_search_engine.mdwn
@@ -1,10 +1,78 @@
-After using it for a while, my feeling is that hyperestradier, as used in
+[[done]], using xapian-omega! --[[Joey]]
+
+After using it for a while, my feeling is that hyperestraier, as used in
 the [[plugins/search]] plugin, is not robust enough for ikiwiki. It doesn't
-upgrade well, and it has a habit of sig-11 on certian input from time to
+upgrade well, and it has a habit of sig-11 on certain input from time to
 time.
 
-So some other engine should be found and used instead. Enrico had one that
-he was using for debtags stuff that looked pretty good.
+So some other engine should be found and used instead. 
+
+Enrico had one that he was using for debtags stuff that looked pretty good.
+That was [Xapian](http://www.xapian.org/), which has perl bindings in
+libsearch-xapian-perl. The nice thing about xapian is that it does a ranked
+search so it understands what words are most important in a search. (So
+does Lucene..) Another nice thing is it supports "more documents like this
+one" kind of search. --[[Joey]]
+
+## xapian
+
+I've invesitgated xapian briefly. I think a custom xapian indexer and use
+of the omega for cgi searches could work well for ikiwiki. --[[Joey]]
+
+### indexer
+
+A custom indexer is needed because omindex isn't good enough for ikiwiki's
+needs for incremental rendering. (And because, since ikiwiki has page info
+in memory, it's silly to write it to disk and have omindex read it back.)
+
+The indexer would run as a ikiwiki hook. It needs to be passed the page
+name, and the content. Which hook to use is an open question.
+Possibilities:
+
+* `filter` - Since this runs before preprocess, only the actual text
+  written on the page would be indexed. Not text generated by directives,
+  pulled in by inlining, etc. There's something to be said for that. And
+  something to be said against it. It would also get markdown formatted
+  content, mostly, though it would still need to strip html, and also
+  probably strip preprocessor directives too.
+* `sanitize` - Would get the htmlized content, so would need to strip html.
+  Preprocessor directive output would be indexed. Doesn't get a destpage
+  parameter, making optimisation hard.
+* `format` - Would get the entire html page, including the page template.
+  Probably not a good choice as indexing the same template for each page
+  is unnecessary.
+
+The hook would remove any html from the content, and index it.
+It would need to add the same document data that omindex would.
+
+The indexer (and deleter) will need a way to figure out the ids in xapian
+of the documents to delete. One way is storing the id of each page in the
+ikiwiki index.
+
+The other way would be adding a special term to the xapian db that can be
+used with replace_document_by_term/delete_document_by_term. 
+Hmm, let's use a term named "P<pagename>".
+
+The hook should try to avoid re-indexing pages that have not changed since
+they were last indexed. One problem is that, if a page with an inline is
+built, every inlined item will get each hook run. And so a naive hook would
+index each of those items, even though none of them have necessarily
+changed. Date stamps are one possibility. Another would be to avoid having
+the hook not do any indexing when `%preprocessing` is set (Ikiwiki.pm would
+need to expose that variable.) Another approach would be to use a
+needsbuild hook and only index the pages that are being built.
+
+#### cgi
+
+The cgi hook would exec omega to handle the searching, much as is done
+with estseek in the current search plugin.
+
+It would first set `OMEGA_CONFIG_FILE=.ikiwiki/omega.conf` ; that omega.conf
+would set `database_dir=.ikiwiki/xapian` and probably also set a custom
+`template_dir`, which would have modified templates branded for ikiwiki. So
+the actual xapian db would be in `.ikiwiki/xapian/default/`.
+
+## lucene
 
 >> I've done a bit of prototyping on this. The current hip search library is [Lucene](http://lucene.apache.org/java/docs/). There's a Perl port called [Plucene](http://search.cpan.org/~tmtm/Plucene-1.25/). Given that it's already packaged, as `libplucene-perl`, I assumed it would be a good starting point. I've written a **very rough** patch against `IkiWiki/Plugin/search.pm` to handle the indexing side (there's no facility to view the results yet, although I have a command-line interface working). That's below, and should apply to SVN trunk.
 
@@ -17,6 +85,12 @@ he was using for debtags stuff that looked pretty good.
 
 >> If this seems a sensible approach, I'll write the CGI interface, and clean up the plugin. -- Ben
 
+>>> The weird thing about lucene is that these are all reimplmentations of
+>>> it. Thank you java.. The C++ version seems like a better choice to me
+>>> (packages are trivial). --[[Joey]]
+
+> Might I suggest renaming the "search" plugin to "hyperestraier", and then creating new search plugins for different engines?  No reason to pick a single replacement. --[[JoshTriplett]]
+
 <pre>
 Index: IkiWiki/Plugin/search.pm
 ===================================================================
@@ -54,20 +128,20 @@ Index: IkiWiki/Plugin/search.pm
 +
  sub import { #{{{
 -       hook(type => "getopt", id => "hyperestraier",
--               call => \&getopt);
+-               call => \&amp;getopt);
 -       hook(type => "checkconfig", id => "hyperestraier",
 +       hook(type => "checkconfig", id => "plucene",
-                call => \&checkconfig);
+                call => \&amp;checkconfig);
 -       hook(type => "pagetemplate", id => "hyperestraier",
--               call => \&pagetemplate);
+-               call => \&amp;pagetemplate);
 -       hook(type => "delete", id => "hyperestraier",
 +       hook(type => "delete", id => "plucene",
-                call => \&delete);
+                call => \&amp;delete);
 -       hook(type => "change", id => "hyperestraier",
 +       hook(type => "change", id => "plucene",
-                call => \&change);
+                call => \&amp;change);
 -       hook(type => "cgi", id => "hyperestraier",
--               call => \&cgi);
+-               call => \&amp;cgi);
  } # }}}
  
 -sub getopt () { #{{{