Why does @@dbts increase after backup/restore?
sql-server
Stijn Stijn
5 The value for `dbi_maxDbTimestamp` is stored on the database boot page. (page 9 in the primary data file).
Martin Smith
SQL Server Assertion <simpletypes.cpp> stack dump when converting float to varchar with 128 style
sql-server-2014 sql-server-2012
Anonymous 2530 Anonymous 2530
14 >1. what’s wrong with convert style 128?
Paul White
7 This must be a bug with earlier versions of SQL Server. You can see it in action [with 2014 on db<>fiddle](https://dbfiddle.uk/um8qeyDl).
Jack Douglas
Retrieving n rows per group
sql-server
Paul White Paul White
3 The typical way to do this in SQL Server 2005 and up is to use a CTE and windowing functions. For top n per group you can simply use `ROW_NUMBER()` with a `PARTITION` clause, and filter against that in the outer query. So, for example, the top 5 most recent orders per customer could be displayed this way:
aaron bertrand
3 Let's start with the basic scenario.
rob farley
1 In DBMS, like MySQL, that do not have window functions or `CROSS APPLY`, the way to do this would be to use standard SQL (89). The slow way would be a triangular cross join with aggregate. The faster way (but still and probably not as efficient as using cross apply or the row_number function) would be what I call the ***"poor man's `CROSS APPLY`"***. It would be interesting to compare this query with the others:
ypercubeᵀᴹ
1 `APPLY TOP` or `ROW_NUMBER()`? What could there possibly be more to say on that matter?
Mikael Eriksson
Incorrect Result with Apply
sql-server
Phist0ne Phist0ne
10 This is a bug in the way SQL Server decides whether a rebind is required with certain plan shapes. It has been in the product since SQL Server 2005.
Paul White
9 > is this a bug in SQL Server?
Martin Smith
Dynamic pivot: sum of sales per month
sql-server
user16947 user16947
4 As others have said this is known as a [`PIVOT`](http://msdn.microsoft.com/en-us/library/ms177410%28v=sql.105%29.aspx). There are several ways in which you can transform your data from rows into columns of data.
taryn
Why does SQL Server require the datatype length to be the same when using UNPIVOT?
sql-server
taryn taryn
2 >*What is the logic behind requiring the same length when using UNPIVOT?*
Paul White
Concatenation Physical Operation: Does it guarantee order of execution?
sql-server
Gordon Linoff Gordon Linoff
6 According to [Craig Freedman](http://blogs.msdn.com/b/craigfr/about.aspx) the order of execution for the concatenation operator is guaranteed.
Mikael Eriksson
5 **No**, there is no documentation from Microsoft guaranteeing the behavior, therefore it is **not guaranteed**.
StrayCatDBA
1 I don't know if you can prove that any observed behavior is always guaranteed, one way or the other, unless you can manufacture a counter-example. In the absence of that, the way to fix the order that results are returned, of course, is to add an `ORDER BY`.
SE Anon or Wiki user
TempDB Version Store cleanup
sql-server-2005
Cougar9000 Cougar9000
8 >*Is the oldest transaction database specific or will SQL Server keep all versions, regardless of the database, if there is an older transaction still active, period?*
Paul White
4 The version store can only clear versions based on the oldest active transaction within the entire *instance*, to support the use of transaction-level snapshot isolation across multiple databases simultaneously. That simply wouldn't work if "old" versions within one database were cleared out in the middle of another database's snapshot transaction.
Jon Seigel
In SQL Server, is parallelism per operator, or something else?
sql-server
worldstar sql worldstar sql
3 >He says that in a parallel plan, every operator gets DOP threads.
Paul White
Why do some rows returned by sys.dm_exec_query_profiles have “???” for the physical operator name?
sql-server-2016
Joe Obbish Joe Obbish
13 [Batch mode adapters](https://dba.stackexchange.com/questions/97650/what-exactly-can-sql-server-2014-execute-in-batch-mode) (places in a query plan in which row processing switches to batch processing or the other way around) show up as `???` in the DMV with a `thread_id` of 0. However, the example query doesn't use batch processing so that isn't the cause here.
Joe Obbish
chat
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