|mnoGoSearch 3.4.1 reference manual: Full-featured search engine software|
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MySQL users may declare mnoGoSearch tables with the
DELAY_KEY_WRITE=1 option. This will make the updating
of indexes faster, as these are not logged to disk until the file is
DELAY_KEY_WRITE excludes updating indexes on
With it, indexes are processed only in memory and written onto disk as a last resort, by the FLUSH TABLES command or at mysqld shutdown. This can take even minutes and impatient user can kill -9 mysql server and break index files with this. Another downside is that you should run myisamchk on these tables before you start mysqld to ensure that they are okay if something killed mysqld in the middle.
Because of it, we didn't include this table
option into the default tables structure. However, as the key information
can always be generated from the data, you should not lose anything by
DELAY_KEY_WRITE. So, use this option at your
This article was supplied by Randy Winch
I have some performance numbers that some of you might find interesting. I'm using RH 6.2 with the 2.2.14-6.1.1 kernel update (allows files larger than 2 gig) and mysql 2.23.18-alpha. I have just indexed most of our site using mnoGoSearch 3.0.18:
mnoGoSearch statistics Status Expired Total ----------------------------- 200 821178 2052579 OK 301 797 29891 Moved Permanently 302 3 3 Moved Temporarily 304 0 7 Not Modified 400 0 99 Bad Request 403 0 7 Forbidden 404 30690 100115 Not found 500 0 1 Internal Server Error 503 0 1 Service Unavailable ----------------------------- Total 852668 2182703
I optimize the data by dumping it into a file
SELECT * INTO OUTFILE, sort it using the system
sort routine into word (CRC) order and then reloading it into the
database using the procedure described in the
mysql online manual.
The performance is wonderful. My favorite test is searching for "John Smith". The optimized database version takes about 13 seconds. The raw version takes about 73 seconds.
Search results: john : 620241 smith : 177096 Displaying documents 1-20 of total 128656 found