# BUG: Complex Query May Cause 1521 Error

Last reviewed: April 30, 1997
Article ID: Q124978

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The information in this article applies to:

- Microsoft SQL Server version 4.2 for OS/2

BUG# OS/2: 1871 (4.2)

## SYMPTOMS

Under certain conditions SQL Server may return error 1521:

       Sort failed because a table in tempdb used for the processing
       of the query had a bad data page count.

This generally occurs when processing very complex queries that may involve any of the following: multiple tables, the use of dynamic indexes, internal sorting, or heavy use of tempdb.

## WORKAROUND

In some cases this problem can be resolved by executing one or more of the following:

1. Run UPDATE STATISTICS on all the tables involved.

2. Modify the query so the optimizer can produce a different query plan. - Make sure your indexes have been designed correctly and efficiently. - Purge or archive any unnecessary data from any tables involved. - Change BETWEEN clauses to the corresponding <= and >= expressions.

NOTE: You may review your query plan by running SET SHOWPLAN ON before executing the query.

## STATUS

Microsoft has confirmed this to be a problem in SQL Server version 4.2 for OS/2. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

> Additional query words:
> Keywords : kbbug4.20 kbother SSrvServer
> Version : 4.2
> Platform : OS/2
> Issue type : kberrmsg
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Last reviewed: April 30, 1997
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