Home/ Questions/Q 180471
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-11T14:35:33+00:00

I have a very high-traffic table with a char(50) field which takes part in

  • 0

I have a very high-traffic table with a char(50) field which takes part in several indexes. This char(50) field allows NULLS, and in that case a NULL value is considered to be the same as a non-NULL, zero-length string for my purposes.

I also disregard leading & trailing whitespace and, while I scrub the data before I insert it, it may also be inserted by means beyond my control.

I have a sproc that is used to copy data from one table to the main table, and it needs to be high-performance. I need to delete duplicate records before inserting the new data and I am using the method discussed in this thread to perform the deletes.

My delete statement looks like this (simplified):

delete masterTable from masterTable t     join incomingDataTable inc on     (         LTRIM(RTRIM(COALESCE(inc.TextField,''))) =               LTRIM(RTRIM(COALESCE(t.TextField,'')))     ) where LTRIM(RTRIM(COALESCE(t.TextField,''))) <> ''

I have read that constructs like LTRIM(RTRIM(…)) are bad. Can my delete statement be improved, and if so, how?

EDIT: Just to clarify, TextField does take part in indexes on both tables. EDIT2: TextField is defined as char(50) in both tables. It is not of type TEXT.

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. It is bad because your JOIN will have to scan the whole index, this is because your condition is not SARGable

    Are you also sure is is a TEXT datatype? Last I checked you could not use LTRIM or RTRIM against a Text datatype column?

    in response to the char against varchar comment, run this

    declare @v varchar(50),@v2 char(50) select @v ='a',@v2 = 'a'  select datalength(@v),datalength(@v2)
    • 0