okay, I have a table with columns A, B, C There is a separate index on all columns If my query looks like this : "WHERE A=? AND (B=? OR C=?) " Then the runtime for 300 queries is about 70 seconds (which is way too long) If my query looks like this: "WHERE A=? AND B=? OR C=? " Then the runtime for 300 queries is about 1 second (which is a lot more sensible). Now, the question is of course, why is mysql so fucking slow, when I just add some brackets? And is the result of the first query equal to this: "WHERE A=? AND B=? OR A=? AND C=? " Or am i missing something? -- ================================================================== Michiel Van Bel PhD student Tel:+32 (0)9 331 36 95 fax:+32 (0)9 3313809 VIB Department of Plant Systems Biology, Ghent University Technologiepark 927, 9052 Gent, BELGIUM mibel@psb.vib-ugent.be http://www.psb.vib-ugent.be http://bioinformatics.psb.ugent.be ==================================================================