more authn_dbd woes

["ernst schoen-rene" <ernstsr@xxxxxxxxx>]

I have a server with several hundred directories, each password protected against their own database.  I added a file, httpd-auth.conf in conf/extra that I include from httpd.conf.  This file has many entries that look like this:

<Directory /var/www/securedocs/1pbpdemo>
        AuthType Basic
        AuthName "Z-TEC International, Inc.: Onepage Plans"
        AuthBasicProvider dbd
        Require valid-user
        AuthDBDUserPWQuery "select password from onepage_1pbpdemo.structure where userid = %s
</Directory>

<Directory /var/www/securedocs/1pbpdemo/admin>
        AuthType Basic
        AuthName "Z-TEC International, Inc. Admin Area"
        AuthBasicProvider dbd
        Require valid-user
        AuthDBDUserPWQuery "select adminPasswd from onepage_1pbpdemo.master where adminUser = %s
</Directory>

when there are only a few of these entries, the system works.  However, when the file is complete with all 17,000 lines, the server produces errors and no longer does authentication correctly.  I get this error:

Internal error: DBD: failed to prepare SQL statements: 

I grep 'failed to prepare' in modules/aaa and srclib/apr and srclib/apr-util, but it isn't found.  As usual, this isn't a terribly informative error.  It would be great if it said WHAT SQL statement it failed to prepare, or if it was out of memory or whatever.
  Any help?