Translations:Administrators/Optimize performance/MySQL/2/en

MySQL uses the index that fits best to perform the query and the decision is made on the cardinality of the index. Indices with a higher cardinality are preferred over indices with lower ones. Problems arise if the cardinality is incorrect and especially the mshop_catalog_index_text MyISAM table containing the fulltext index is known for being vulnerable to this. Therefore, it's a good idea to check the cardinality values in the mshop_catalog_index_* tables once in a while and especially if you think the product search is slower than in the past while the number of products is not much higher than before.