Re: isolation level RR

Katarina Hamzova wrote: > How does isolation level repeatable read work > I thought it places share locks on every row > selected in queries in transaction - > i did this: > begin work; > set isolation to repeatable read > select * from table where ...> ... > i expected it places locks > on rows according to where clause. > But it placed share lock on table . > Am i missing something ? Up to a point, a query operating under repeatable read places a shared lock on every row in encounters while trying to locate rows that fit the query. As I have understood it, if the optimizer guesses it will looking at some number of rows - i.e. will place more than than some large number of locks (or a percentage?) - it gives up on this scheme and just places a shared lock on the whole table. The reasoning behind this makes sense (albeit arguable) but I can't go into it here. I hope that explains the mystery. -- -- Jake (Never yelled "CROWDED THEATER!" during a fire) +------------------------------------------------------------+ | The expedient performance of a task with excessive concern | | regarding its duration-to-completion engenders a virtual | | certainty of diminished benefit therefrom. | | -- Benjamin Franklin (but he said it in 3 words) | +------------------------------------------------------------+