[sword-devel] Search up to 5.8 times faster now :)

Joachim Ansorg junkmail at joachim.ansorgs.de
Wed Jun 2 15:25:56 MST 2004

Hash: SHA1

the standard search function is now up to 5 times faster than before.

Let me explain.
A search in a module did the following:
	1. Get the text of a key by calling all the strip filters ()
	2. Search the search words in the stripped down text
	3. If it was found add it to the result
We assume a module with 6 strip filters.
This means the expensive StripText() function got called 30000*6=180000 times.

Now we check for the words in the raw text and only check keys which had a 
valid match in the raw text if they match in the stripped down text.
If we assume a normal query returns 100 results the StripText function gets 
called 100*6=600 times which saves a lot of time.

Old/new comparision:
	time ./old/examples/cmdline/search KJV Revelation
		real    0m18.912s
		user    0m18.090s
		sys     0m0.780s

	time ./new/examples/cmdline/search KJV Revelation
		real    0m3.396s
		user    0m2.540s
		sys     0m0.830s
Which is an improvement factor of 5.6 :)

	./new/examples/cmdline/search WEB God
only takes 2.1 secs now.

Another example:
	time ./old/examples/cmdline/search KJV God
		real    0m20.371s
		user    0m18.130s
		sys     0m0.950s

	time ./new/examples/cmdline/search KJV God
		real    0m5.566s
		user    0m4.730s
		sys     0m0.810s	
This is "only" 3.7 times faster, because searching in the raw text gives more 
hits which means more calls to StripText(). I tested it with a search for " " 
which means all verses and it's as slow as the old one. Which ones usual 
search queries are a lot faster than before.

The fix is in CVS now.

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