Hello, I'm experiencing a strange problem with query performance runing on SQL2005. The database has 10+ tables, but we need to run really specific queries in only 1 table with these caracteristics : - 1 million rows - we run everyday a few thousands queries on that table, each query is unique (adhoc plan), and not parameterizable. (we cannot optimize this) - rows have a lot of nvarchar data - all queries use a lot of LIKE / NOT LIKE statement (we cannot find any work-around to that point, Fulltext is not adequate in that case) - when LIKE operations are performed on columns, we always create a duplicate column to optimize some search stuff, like putting everything in Low Case, using Latin1_General_BIN collation, ... - we have some indexes on short nvarchar columns, only those where we use an exact '=' statemen - we have another index on a float column - all usefull indexes and statistics are manually created on that table - the nvarchar content of the table changes only once a day. It means we do all optimization (indexes / stats) just after the update, and there is no change on nvarchar data until the next update (24 hours later) I found that when "Auto Create Statistics" is enabled on the database, that queries are really runing slower : - "Auto Create Statistics" enabled : 57 min to run all queries - "Auto Create Statistics" disabled and all auto-created stats deleted : 7 min to run the same queries It means that queries are running 8x slower when "Auto Create Statistics" is enabled! Another interesting point : just after disabling "Auto Create Statistics", the queries continue to perform slowly until I manually delete all statistics created automatically for that table (the one begining with "_WA_Sys_"). It could mean that it's not a stat creation issue, but only the existence of that statistics that could change the query plan. But in both cases, the execution plan for the same query seems to beexactly the same (same aspect, same costs). I also tried to enable the Asyncstats update : no change. The problem is that for all the other tables in the database, the "Auto Create Statistics" is a good thing and useful. But not for that specific table. Two questions : - Is it possible to disable "Auto Create Statistics" on a specific table? (I did not find anything about that in the BOL) - If not, is there another work-around to deal with that kind of performance drop? Thanks.