Hello,
I had a 135MB, 1256132 lines, '@' separated text file containing
various words and text fields (like a dictionary).
Example record:
[EMAIL PROTECTED]@[EMAIL PROTECTED],[EMAIL PROTECTED] altana : μικρός ανθόκηπος - εξώστης,
ταράτσα@@@@@@@@@@@
I imported the data in sqlite3.3.6 but when querying with the 'like'
operator, the performance way too slow (about 1.5-2 seconds/query):
>time sqlite3 dicts.db "select * from table1 where word like 'asdf%';"
1.156u 0.491s 0:01.64 100.0% 0+0k 0+0io 0pf+0w
Creating an index did not help at all. Using the COLLATE NOCASE is not
of help either since text encoding is not iso-8859-1 (but still is 8-bit).
FYI using egrep takes only 0.14s to get results in the worse case scenario:
>time egrep -i "[EMAIL PROTECTED]@[EMAIL PROTECTED]@[EMAIL PROTECTED]@asdf"
meta.txt
0.077u 0.069s 0:00.14 92.8% 0+0k 0+0io 0pf+0w
1) I know egrep is not a DB but does sqlite use such an inefficient
search algorithm for content that cannot be indexed? Why not reverting
to simple 'grep-like' methods? Or am I missing something trivial here?
2) Why doesn't an index raise performance at all in this case? Is it
because non-latin chars are used?
Please clarify, I'm really confused about this.
Thank you.
Spiros Ioannou
p.s.
if answers to (1) and (2) don't help, I'm going to write a php-egrep
plugin to avoid popen-ing :-)
--
Image Video & Multimedia Systems Lab.
Department of Electrical & Computer Eng.
National Technical University of Athens
http://www.image.ece.ntua.gr
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