Maria's journey in the data fields

Today I have played with partition merging. The target of this was to see how long it can take, which locks are being held etc. I see that even if partions are empty, the minimum time that it takes is 30 sec ( 2x2.66 CPU 7Gb RAM ). Most of the merge time the folowing system tables are locked exclusive which means that no new query compilations, no schema changes are not allowed: sysrowsetrefs,sysrowsets,sysallocunits,syssingleobjrefs, sysobjvalues,syshobtcolumns,sysrowsetcolumns,sysserefs,syshobts,sysschobjs,sysclsobjs. If there are any schema modification processes running in the database or any data modification processes merge of course waits till those are finished and it can aquire the required locks. If there are other tables that reside on the same partition function, Sch-M locks are placed on them. Regardless of partition sizes, the merged partition will reside on the filegroup that did not hold the merged boundary. This means that is you need to merge many partitions, start ...

Yes. Even if constraint checks partitioning column and "bad" data can exist in one partition only. See for yourself: I create table natively partitioned on integer field with another char field to fill more pages (full script at the end of message), I fill the table with 1000000 rows. I also have a nonclustered index in partitioned column. For a design of our application i need to add check constraint (i >2) to the table. create partition function f (int) as range for values (5,50,100,500); create partition scheme s as partition f all to ([primary]) create table t ( i int not null,c char(2000)) on s(i) declare @i int set @i = 1 while @i begin insert into t select @i,replicate('a',2000) set @i = @i + 1 end create index ind1 on t(i) Checking the view dm_db_index_operational_stats I see that sql server scanned index on ALL partitions to check if data ok for the constraint : field range_scan_count changed from 0 to 1 in all partitions, page_lock_count also changed for...