Wildcard searching between words with CRC mode in Sphinx

Question

I use sphinx with CRC mode and min_infix_length = 1 and I want to use wildcard searching between character of a keyword. Assume I have some data like these in my index files:

name
-------
mickel
mick
mickol
mickil
micknil
nickol
nickal

and when I search for all record that their's name start with 'mick' and end with 'l':

select * from all where match ('mick*l')

I expect the results should be like this:

name
-------
mickel
mickol
mickil
micknil

but nothing returned. How can I do that?

• I know that I can do this in dict=keywords mode but I should use crc mode for some reasons.

• I also used '^' and '$' operators and didn't work.

Answer 1

You can't use 'middle' wildcards with CRC. One of the reaons for dict=keywords, the wildcards it can support are much more flexible.

With CRC, it 'precomputes' all the wildcard combinations, and injects them as seperate keywords in index, eg for

eg mickel as a document word, and with min_prefix_len=1, indexer willl create the words:

mickel
mickel*
micke*
mick*
mic*
mi*
m*

... as words in index, so all the combinations can match. If using min_infix_len, it also has to do all the combinations at the start as well (so (word_length)^2 + 1 combinations)

... if it had to precompute all the combinations for wildcards in the middle, would be a lot more again. Particularly if then allows all for middle AND start/end combinations as well)

---

Although having said that, you can rewrite

select * from all where match ('mick*l')

as

select * from all where match ('mick* *l')

because with min_infix_len, the start and end will be indexed as sperate words. Jus need to insist that both match. (although can't think how to make them bot match the same word!)