Re: isolation level RR

Katarina Hamzova wrote: > PLEASE HELP ME > > My question : > 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 ? Yes. For the select statement to be repeatable, none of the rows that were read the first time can be changed or deleted. But that's just half the problem. No _other_ row in the table can be changed so that it now meets the 'where' condition when it did not before. Nor can any new row be inserted that would meet the 'where' conditions. The only way to meet these conditions is to lock the entire table. > > > Informix On line 7.20 DSA - SNI > Informix On line 7.22 WGS - Win NT > databases created in non Ansi mode > unbuffered logging > > thanks > katarina > -- > Katarina Hamzova Voice : +42 7 5384324 > SWH s.r.o Bratislava > Slovakia > Internet : Katarina.Hamzova@swh.sk -- Bill Backs Senior Partner Sobek Consulting A small consulting firm specializing in database design and tuning, and data modeling. Visit our web site at www.sobek.com