Table: Outlook_Store
Holds Outlook(R) StoreID values to save space and aid in indexing. Each store_id must be unique. This table does not support updates, only inserts and deletes. Once a record exists it is read-only.

"For the Exchange message stores, entry id includes the full distinguished name of the mailbox, which is not limited in length AFAIK. Since MAPI starts barking when a property size goes above about 4k (you need to open the property as IStream, not with IMAPIProp::GetProps(...), etc), it would be relatively safe to alllocate 8192 chars for the entry ids - if your code breaks, so would Outlook itself."
-- Dmitry Streblechenko (MVP)
http://www.dimastr.com/, http://groups.google.com/group/microsoft.public.outlook.program_vba/browse_frm/thread/f768d385c8dd4a27/1df02bd5c153c6bd%231df02bd5c153c6bd
Columns
NameTypeConstraintsDescription
outlook_store_KEYintNOT NULLAssigned by COMMON_dp_Allocate_Unique_Identifiers. A unique value assigned to this StoreID so that linking to this StoreID uses only 4 bytes.
store_idvarbinary (4096)NOT NULLHolds the binary value of the Outlook(R) StoreID. Convert to a hexadecimal string without the 0x prefix (2 characters for each byte) the COM interface representation. Unique (enforced by a trigger.)
store_id_checksumintNOT NULLSince the store_id column is wider than 900 bytes, the SQL Server CHECKSUM function is used to compute an indexable column. This column is not unique.
Primary key
NameColumnsDescription
PK_Outlook_Store$outlook_store_KEYoutlook_store_KEYCLUSTERED
Indexes
NameColumnsDescription
IX_Outlook_Store$store_id_checksumstore_id_checksum
Incoming foreign keys
NameColumnsReferencing tableDescription
FK_Outlook_Index_Folder_Firm__Outlook_Store__outlook_store_KEYoutlook_store_KEYOutlook_Index_Folder_Firm
FK_Outlook_Contact_Synchronization_Folder__Outlook_Store__outlook_store_KEYoutlook_store_KEYOutlook_Contact_Synchronization_Folder
FK_Outlook_Item__Outlook_Store__outlook_store_KEYoutlook_store_KEYOutlook_Item

Schema diagram