min_infix_len

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. When minimum 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.

Perfect word matches can be differentiated from infix matches, and ranked higher, by utilizing all of the following options: a) dict=keywords (on by default), b) index_exact_words=1 (off by default), and c) expand_keywords=1 (also off by default). Note that either with the legacy dict=crc mode (which you should ditch anyway!), or with any of the above options disable, there is no data to differentiate between the infixes and full words, and thus perfect word matches can't be ranked higher.

Example:

min_infix_len = 3
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