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Could you list the limitations of the SimpleDB support. I am currently evaluating your product and it is difficult to know if I am seeing a limitation or a bug when comparing behaviour between SQL and SDB. Limitations if known can likely be worked around but discovering them ourselves can be a bit frustrating. I am assuming so far (correct me if I am wrong) 1) No eager loading Anything else? Thanks PS. Are you likely to be supporting Azure Storage and/or SQL Data Services when they out of beta? |
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Hello Daren, We have attempted to list limitations in the help file under Help Topics > Databases > Amazon SimpleDB, but this is not comprehensive. We will add the features you've identified to this topic. Some others: - No batching of inserts, updates or deletes - No calculations or functions, no stored procedures or views - The Count method currently works by querying -- we know Amazon have recently added a COUNT(*) keyword but we haven't updated our code to use that yet - Some limitations on the kind of queries that can be used e.g. no In or Between queries. - Paging is done client-side. - No Distinct support. - No ValidatePresence support. - No cascade deletes. - Only certain IdentityMethods are supported (Guid, GuidComb or homebrewed identities via overriding Entity.GeneratedId()). Obviously, the limitations on the kinds of queries also apply to queries formed through LINQ -- e.g. you cannot use CLR properties or methods such as "where o.Name.StartsWith(...)" because these translate into SQL functions. Also there are some things that SimpleDB supports but LightSpeed doesn't provide access to, specifically multi-value attributes; also, as the StartsWith example shows, we also do not yet support the Amazon query language's special operators. I think that's the lot. However it's possible I've missed something -- if you're in doubt about whether something you're seeing is a bug or a limitation then please do post and we will aim to get you an answer quickly. Also we would welcome feedback on this list -- some of these limitations are inherent in SimpleDB but others are just because we have not yet had time to add the feature. Re Azure and SQL Data Services: it is extremely likely that we will support these once they have stabilised a bit. However, we know that Microsoft's cloud database plans are evolving rapidly as they get customer feedback, so we are not currently actively working on support for these platforms. |
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Optimistic Concurrency seems to be absent too. I guess because of the eventual concurrency system at SDB. Thanks this list will help. Also some feedback on the help file, In areas it seems to be refering to a version with no designer (was that version 1?) it can be a little confusing. |
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correction: eventual concurrency = eventual consistency |
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Hmm, you're right, optimistic concurrency checking will be unreliable because of eventual consistency. The same problem will affect soft delete. Thanks for pointing this out. Thanks for the feedback on the help file. There is a conscious intent to document the real objects and classes, rather than hide it all behind the designer magic, but I take your point that there are several areas (such as the "magic fields" of optimistic concurrency checking and soft deletion) where we should give more priority to how things are surfaced in the designer, or start from the designer and then lead into the underlying stuff. |
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