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EWS item identifier and your database

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Several times we’ve heard people ask what the maximum size is for the EWS identifier. This question usually comes up when developers are designing a database schema that will store the EWS identifier in a fixed-width column. Our answer is that the EWS item identifier should be contained in a fixed-width column of 512 characters. So, how confident should you feel about defining your field at 512 characters? Well, of course we reserve the right to change the format, and the resulting maximum length of the EWS identifier. The chances of that occurring, however, are very slim. The EWS identifier format has been changed once between Exchange 2007 and 2007 SP1, early on in the adoption of EWS, but we acknowledge that changing the format at this point would have unwelcome effects on both customer and Microsoft applications that interoperate with Exchange. In short, we do not expect the EWS identifier format to change.

Comments

  • Anonymous
    March 16, 2017
    Is there any documentation on the format of the EWSID? It appears that the EWSID for folders and the messages contained in those folders are very similar.. Our application is storing folder EWSID's and EmailMessage EWSID's and if the fields are related we can compress the data.. Thanks in Advance!!
    • Anonymous
      March 21, 2017
      No, how they're built isn't documented. They are intended to be opaque to EWS apps.
  • Anonymous
    May 22, 2017
    Would a varchar(512) be acceptable or does it need to be nvarchar?
  • Anonymous
    July 21, 2017
    Documentation here (https://msdn.microsoft.com/en-us/library/office/dn605828(v=exchg.150).aspx#bk_WorkingWithIdentifiers) 512 bytes but you say here 512 characters. Do you know if varchar(512) is sufficient? If I use nvarchar(512) sql server tells me the column is too big to index.