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Posts Tagged / ANSI_Padding

  • Aug 29 / 2017
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Data Modeling and Database Design, Table Partitioning

ALTER TABLE SWITCH statement failed because column ‘%’ does not have the same ANSI trimming semantics in tables ‘%’ and ‘%’.

While trying to switch a partition from one table to another i got following error message

ALTER TABLE SWITCH statement failed because column ‘%’ does not have the same ANSI trimming semantics in tables ‘%’ and ‘%’.

It is related to difference of ANSI Padding setting between any column of both the tables involved in partition switch. Surprisingly i did not find the match of this setting as a partition switch prerequisite in BOL.

ANSI_Padding

ANSI Padding relates to storage of char, varchar, binary, and varbinary data types. It is by default ON in SQL Server unless explicitly set OFF for a connection. Best practice is to always set it ON. Data types like nchar, nvarchar, ntext, text, image, varbinary(max), varchar(max), and nvarchar(max) have always ANSI_Padding ON and cannot be changed. So we will be dealing with char, varchar, binary, and varbinary data typesto manage this setting.

Problem while switching partition

Coming back to our partition switch issue, we are required to eliminate the ANSI_Padding difference between both tables to perform the partition switch. Let us create two tables, one with ANSI_Padding ON and other with OFF.

Above script will create tbl_APOff with ANSI_Padding OFF and tbl_APOn with ANSI_Padding ON. Both tables are exact copies of each other except the difference of ANSI_Padding setting that can be verified with following script

Columns does not have the same ANSI trimming semantics

At this stage we have idea of issue and a script to detect and analyze the issue.

Fix

To fix the ANSI_Padding difference issue we have two primary  options.

  • ALTER the ANSI_Padding  setting of columns in one table to match other
  • Recreate one of these tables with ANSI_Padding setting matching to other one

While applying any of above approach we should prefer to make ANSI_Padding ON so that best practice can be implemented.

ALTER the ANSI_Padding  setting

Let us change the ANSI_Padding setting for both columns in tbl_APOff. This can be done with following ALTER COLUMN commands.

Now we can match and verify the ANSI_Padding setting in both tables by re-executing the previous script. And result confirms the fix.

Match the ANSI_Padding setting of columns in two tables

Issue is fixed and we can switch the partitions

Recreate table with modified ANSI_Padding

As a second option you can drop and re-create the table and do not forget to mention

at start of script.

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