SQL2008 fulltext index search without word breakers - sql

I are trying to search an FTI using CONTAINS for Twitter-style usernames, e.g. #username, but word breakers will ignore the # symbol. Is there any way to disable word breakers? From research, there is a way to create a custom word breaker DLL and install it and assign it but that all seems a bit intensive and, frankly, over my head. I disabled stop words so that dashes are not ignored but I need that # symbol. Any ideas?

You're not going to like this answer. But full text indexes only consider the characters _ and ` while indexing. All the other characters are ignored and the words get split where these characters occur. This is mainly because full text indexes are designed to index large documents and there only proper words are considered to make it a more refined search.
We faced a similar problem. To solve this we actually had a translation table, where characters like #,-, / were replaced with special sequences like '`at`','`dash`','`slash`' etc. While searching in the full text, u've to again replace ur characters in the search string with these special sequences and search. This should take care of the special characters.

Related

Lucene: problems when keeping punctuation

I need Lucene to keep some punctuation marks when indexing my texts, so I'm now using a WhitespaceAnalyzer which doesn't remove the symbols.
If there is a sentence like oranges, apples and bananas in the text, I want the phrase query "oranges, apples" to be a match (not without the comma), and this is working fine.
However, I'd also want the simple query oranges to produce a hit, but it seems the indexed token contains the comma too (oranges,) so it won't be a match unless I write the comma in the query too, which is undesirable.
Is there any simple way to make this work the way I need?
Thanks in advance.
I know this is a very old question, but I'm bored and I'll reply anyway. I see two ways of doing this:
Creating a TokenFilter that will create a synonym (e.g. insert a token into the stream with a 0 position length) each time a word contains punctuation with the non-puncuation version.
Add another field with the same content but using a standard tokenizer that removes all punctuation. Both fields will be matched.

Mysql query: it's not fetching first result

I have below values in my database.
been Lorem Ipsum and scrambled ever
scrambledtexttextofandtooktooktypetexthastheunknownspecimenstandardsincetypesett
Here is my query:
SELECT
nBusinessAdID,
MATCH (`sHeadline`) AGAINST ("text" IN BOOLEAN MODE) AS score
FROM wiki_businessads
WHERE MATCH (`sHeadline`) AGAINST ("text" IN BOOLEAN MODE)
AND bDeleted ="0" AND nAdStatus ="1"
ORDER BY score DESC, bPrimeListing DESC, dDateCreated DESC
It's not fetching first result, why? It should fetch first result because its contain text word in it. I have disabled the stopword filtering.
This one is also not working
SELECT
nBusinessAdID,
MATCH (`sHeadline`) AGAINST ('"text"' IN BOOLEAN MODE) AS score
FROM wiki_businessads
WHERE MATCH (`sHeadline`) AGAINST ('"text"' IN BOOLEAN MODE)
AND bDeleted ="0" AND nAdStatus ="1"
ORDER BY score DESC, bPrimeListing DESC, dDateCreated DESC
The full text search only matches words and word prefixes. Because your data in the database does not contain word boundaries (spaces) the words are not indexed, so they are not found.
Some possible choices you could make are:
Fix your data so that it contains spaces between words.
Use LIKE '%text%' instead of a full text search.
Use an external full-text search engine.
I will expand on each of these in turn.
Fix your data so that it contains spaces between words.
Your data seems to have been corrupted somehow. It looks like words or sentences but with all the spaces removed. Do you know how that happened? Was it intentional? Perhaps there is a bug elsewhere in the system. Try to fix that. Find out where the data came from and see if it can be reimported correctly.
If the original source doesn't contain spaces, perhaps you could use some natural language toolkit to guess where the spaces should be and insert them. There most likely already exist libraries that can do this, although I don't happen to know any. A Google search might find something.
Use LIKE '%text%' instead of a full text search.
A workaround is to use LIKE '%text%' instead but note that this will be much slower as it will not be able to use the index. However it will give the correct result.
Use an external full-text search engine.
You could also look at Lucene or Sphinx. For example I know that Sphinx supports finding text using *text*. Here is an extract from the documentation which explains how to enable infix searching, which is what you need.
9.2.16. min_infix_len
Minimum infix prefix length to index. Optional, default is 0 (do not index infixes).
Infix indexing allows to implement wildcard searching by 'start*', '*end', and 'middle' wildcards (refer to enable_star option for details on wildcard syntax). When mininum infix length is set to a positive number, indexer will index all the possible keyword infixes (ie. substrings) in addition to the keywords themselves. Too short infixes (below the minimum allowed length) will not be indexed.
For instance, indexing a keyword "test" with min_infix_len=2 will result in indexing "te", "es", "st", "tes", "est" infixes along with the word itself. Searches against such index for "es" will match documents that contain "test" word, even if they do not contain "es" on itself. However, indexing infixes will make the index grow significantly (because of many more indexed keywords), and will degrade both indexing and searching times.

Accented character replacement for search then reinserted afterwards

Basically my issue is that users would like to search for a french word that has accented characters but without typing in the accented characters and then have the actual accented word appeared highlighted if found... So for example they would type in "declare" but in the result sets it would look like "déclare" and if found "déclare" would be highlighted.
My first thought was to just simply replace the characters with a regex but then I remembered that I would need to re-insert the replaced characters after the search... I was thinking of then using some sort of character map that would track position and the character so that when the search was finshed I could put the result set back to the way it was. This seems a little brute force to me and I was wondering if anyone had a better alternative? I'm using Visual Studio 2005 with this app.
Any advice would be much appreciated!
Thanks
A regular expression by default matches text. The "replacement" mode is not the normal mode. So, what you want is in fact the default. The precise syntax will depend on your Regex engine, e.g. in .Net you'd use Regex.IsMatch()

MySQL full text search for words with three or less letters

I'm trying to get my full text search (in boolean mode) to retrieve words with three letters or less.
Currently, if I search for something like "NBA", I don't get any results.
However, if I append the wild card operator "*" to the search term, I get results.
I also read that you could remove the three word limit in my.ini, but I'm wondering if there was a better way to do this on the fly.
This section of the manual might interest you : 11.8.6. Fine-Tuning MySQL Full-Text Search (quoting a portion of it) :
The minimum and maximum lengths of
words to be indexed are defined by the
ft_min_word_len and ft_max_word_len
system variables. The
default minimum value is four
characters; the default maximum is
version dependent. If you change
either value, you must rebuild your
FULLTEXT indexes. For example, if you
want three-character words to be
searchable, you can set the
ft_min_word_len variable by putting
the following lines in an option file:
[mysqld]
ft_min_word_len=3
Then you must restart the server and
rebuild your FULLTEXT indexes.
(You should read that page, for more informations I didn't copy-paste ;-) )

What is causing the LIKE statement to disregard html-tags, words after commas, or end in periods?

I'm working on a search module that searches in text columns that contains html code. The queries are constructed like: WHERE htmlcolumn LIKE '% searchterm %';
Default the modules searches with spaces at both end of the searchterms, with wildcards at the beginning and/or the end of the searchterms these spaces are removed (*searchterm -> LIKE '%searchterm %'; Also i've added the possibility to exclude results with certain words (-searchterm -> NOT LIKE '% searchterm %'). So far so good.
The problem is that words that that are preceded by an html-tag are not found (<br/>searchterm is not found when searching on LIKE '% searchterm.., also words that come after a comma or end with a period etc.).
What i would like to do is search for words that are not preceded or followed by the characters A-Z and a-z. Every other characters are ok.
Any ideas how i should achieve this? Thanks!
Look into MySQLs fulltextsearch, it might be able to use non-letter characters as delimiters. It will alsow be much much faster than a %term% search since that requires a full table-scan.
You could use a regular expression: http://dev.mysql.com/doc/refman/5.0/en/regexp.html
Generally speaking, it is better to use full text search facilities, but if you really want a small SQL, here it is:
SELECT * FROM `t` WHERE `htmlcolumn` REGEXP '[[:<:]]term[[:>:]]'
It returns all records that contain word 'term' whether it is surrounded with spaces, punctuation, special characters etc
I don't think SQL's "LIKE" operator alone is the right tool for the job you are trying to do. Consider using Lucene, or something like it. I was able to integrate Lucene.NET into my application in a couple days. You'll spend more time than that trying to salvage your current approach.
If you have no choice but to make your current approach work, then consider storing the text in two columns in your database. The first column is for the pure text, with punctuation etc. The second column is the text that has been pre-preprocessed, just words, no punctuation, normalized so as to be easier for your "LIKE" approach.