Hi! 2011/5/12 Albe Laurenz <laurenz.albe@xxxxxxxxxx>: > Durumdara wrote: >>Two table: >>Main >>Lookup >> >>The query is: >>select Main.*, Lookup.Name >>left join Lookup on (Main.Type_ID = Lookup.ID) > > hat's not correct SQL, but I think I understand what you mean. Sorry, the from is missed here... :-( > > >>Lookup: >>ID Name >>1 Value1 >>2 Value 2 >>3 Value 3 >> >>Many records is in Main table (for example 1 million). >> >>What happens in this case (C = connection): >> >>C1.) begin read committed >>C1.) starting this query >>C1.) query running >>C2.) begin read committed >>C2.) update Lookup set Name = "New2" where ID = 2 >>C2.) commit >>C1.) query running >>C1.) query finished >> >>Is it possible to the first joins (before C2 modifications) are >>containing "Value2" on the beginning of the query and "New2" on the >>end of the query? >>So is it possible to the long query is containing not consistent state >>because of C2's changing? For example mixing "Value2" and "New2"? > > No, this is not possible. Thanks! Great! > > See > http://www.postgresql.org/docs/current/static/transaction-iso.html#XACT- > READ-COMMITTED : > > When a transaction uses this [read committed] isolation level, a > SELECT query > (without a FOR UPDATE/SHARE clause) sees only data committed before > the query began; > it never sees either uncommitted data or changes committed during > query execution > by concurrent transactions. Query is meaning statement here? For example if I have more statement in one "Query" are they running separatedly? They can be see the modifications? Query text (or stored procedure body): "insert into ... ;" + "update ...;" + "select ..." Are they handled as one unit, or they are handled one by one? AutoCommit = False! Thanks: dd -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
