Paul White @SQL_Kiwi

I live in Aotearoa New Zealand and write about SQL Server internals at https://t.co/nuZwOWQzHy Microsoft MVP 2011-2022 DBA Stack Exchange Mod 2015-2025 sql.kiwi Paraparaumu, New Zealand Joined April 2010

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Paul White @SQL_Kiwi

3 months ago

I don't really understand why anyone is excited about nested CTEs, but if you want to try it on SQL 2025 CTP2 box, enable TF 15320 (session or global). Currently only documented for 'Fabric' whatever that is docs.microsoft.com/en-us/sql/t-sq…

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Paul White @SQL_Kiwi

4 months ago

Looks like 'expression indexes' are coming to SQL Server 2025. This is valid syntax on CTP 2 when trace flag 17152 is enabled: CREATE INDEX ix ON MyTable (n * 2); It creates a computed column for you, named e.g. $expression_index_B18729F8A924473FA0DF2CB95D9B2E01.

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Paul White @SQL_Kiwi

4 months ago

Interesting undocumented USE HINTs in SQL Server 2025 CTP 2: * DISABLE_PERFORMANCE_SORT_FOR_DML sets DMLRequestSort to false like TF 8795 * DISABLE_OPTIONAL_PARAMETER_OPTIMIZATION * PARALLEL_DML_FOR_VECTOR_INDEX_BUILD * DISABLE_SCALABLE_SUBTREE

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Darling Data @erikdarlingdata

4 months ago

TRUNCATE TABLE WITH PARTITIONS causes data corruption with non-aligned partitions feedback.azure.com/d365community/…

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Paul White @SQL_Kiwi

5 months ago

This is a really funny SQL Server bug dbfiddle.uk/iUmhLPln DECLARE @t table (i smallint NOT NULL PRIMARY KEY); INSERT @t (i) VALUES (256); SELECT TRY_CONVERT(tinyint, T.i) FROM @t AS T; SET STATISTICS XML ON; -- Oops! SELECT T.i FROM @t AS T WHERE TRY_CONVERT(tinyint,…

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Paul White @SQL_Kiwi

5 months ago

New article: Recording Debugging Information Inside a SQL Server Function Call We cannot use PRINT or RAISERROR statements within a T-SQL function body for debugging purposes. This article presents a workaround using session context. sql.kiwi/2025/04/debug-…

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Paul White @SQL_Kiwi

5 months ago

FYI my rates for US residents have increased by 25% from today

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Paul White @SQL_Kiwi

5 months ago

New article: Accessing a SQL Server Table Variable in a Different Scope Two ways to access a SQL Server table variable outside its declaration scope. sql.kiwi/2025/04/access…

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Paul White @SQL_Kiwi

5 months ago

Since 2008, XACT_STATE includes system transactions, so it works correctly in triggers. But: -- XACT_STATE = 0 PRINT 'XACT_STATE = ' + CONVERT(varchar(11), XACT_STATE()); -- XACT_STATE = 1 PRINT CONCAT('XACT_STATE = ', XACT_STATE()); 😲

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Paul White @SQL_Kiwi

5 months ago

You can't use PRINT or RAISERROR in a SQL Server function to emit debugging data. A workaround: Call sp_set_session_context to save info inside the function. Read the data using SESSION_CONTEXT after the function call.

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Paul White @SQL_Kiwi

5 months ago

New article: Avoid optional_spid Plan Cache Issues when Sharing Temp Tables How to avoid unnecessary stored procedure compilation and plan cache pollution when using shared SQL Server temporary tables. sql.kiwi/2025/03/avoid-…

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Paul White @SQL_Kiwi

5 months ago

New article: Sharing Data Between Procedures using a Cursor Contrary to the product documentation, SQL Server cursor variables can be used to share data between stored procedures in the input or output direction (but not both). sql.kiwi/2025/03/sharin…