Sorry I only use proper DB's like PostgreSQL and MSSQL who optimizer's have no problems with this ;). Also what I like about the count approach is you can do "

Sorry I only use proper DB's like PostgreSQL and MSSQL who optimizer's have no problems with this ;). Also what I like about the count approach is you can do "show me all the posts with at least 2 out of the 3 tags matching" fuzzier search if you desire.