… columns: – Query can be index covered if you select limited number of columns. – Selecting all columns may require more network traffic and… having 100 float columns, vs selecting only couple of them So instead of thinking if it would slow things down in your case… other reasons SELECT * is bad practice besides performance – for example reffering to columns by offsets may break if column inserted between other…

… of 32 bytes vs 4 bytes for key value – if you would use integer key and insert data in random … Innodb tables aspect of primary key selection – you often can gain a lot by selecting primary key which provides data … about 200 rows/sec and the it is still slowing down a bit as key file growths. So in …

… this ? Say you have query like “SELECT page,count(*) cnt FROM logs GROUP… scan the table, when for each row insert (or update) row in the temporary … of index accesses, joins etc may be slowed down 100-1000 then going from…. Finally let me talk about modeling vs benchmarking for capacity planning. I’m…