--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lucene/src/luan/modules/lucene/Versioning.luan	Mon Jun 15 01:22:58 2015 -0600
@@ -0,0 +1,56 @@
+local Luan = require "luan:Luan"
+local error = Luan.error
+local pairs = Luan.pairs or error()
+local Number = require "luan:Number"
+local integer = Number.integer or error()
+local long = Number.long or error()
+local String = require "luan:String"
+local matches = String.matches or error()
+local sub = String.sub or error()
+local string_to_number = String.string_to_number or error()
+local Table = require "luan:Table"
+local clone = Table.clone or error()
+local Lucene = require "luan:lucene/Lucene"
+require "luan:logging/init"
+local Logging = require "luan:logging/Logging"
+
+local logger = Logging.logger "lucene versioning"
+
+
+local M = {}
+
+function M.update(db,steps,version)
+	local doc = db.get_document"type:version" or { type="version", version=integer(0) }
+	while doc.version < version do
+		doc.version = integer(doc.version + 1)
+		logger.error("step "..doc.version)
+		db.update_in_transaction( function()
+			local step = steps[doc.version]
+			step and step(db)
+			db.save(doc)
+		end )
+	end
+end
+
+
+-- hack to deal with latest changes
+function M.a_big_step(db)
+	db.indexed_fields["id index"] = Lucene.type.string
+	db.advanced_search( Lucene.literal"id index" .. ":*", function(_,doc_fn)
+		local doc = doc_fn()
+		for field, value in pairs(clone(doc)) do
+			if matches(field,".* index") then
+				local new_field = sub(field,1,-7)
+				db.indexed_fields[new_field] or error("field '"..new_field.."' not indexed")
+				doc[new_field] = value
+				doc[field] = nil
+			end
+		end
+		doc.id = long(string_to_number(doc.id))
+		db.save(doc)
+	end )
+	db.indexed_fields["type index"] = Lucene.type.string
+	db.delete( Lucene.literal"type index" .. ":*" )
+end
+
+return M