queries | PostgreSQL database access | Database library

TL;DR You are missing some resolvers. Your query resolvers are trying to do the job of the missing resolvers. Your resolvers must return data in the right shape.

In other words, your problems are with configuring Apollo Server's resolvers. Nothing Lambda-specific, as far as I can tell.

GraphQL doesn't know how to "resolve" an author's books, for instance. Add a Author {books(parent)} entry to Apollo Server's resolver map. The corresponding resolver function should return a list of book objects (i.e. [Books]), as your schema requires. Apollo's docs have a similar example you can adapt.

Here's a refactored author query, commented with the resolvers that will be called:

If the members of a container are not destructible, then the container could never do anything except add new elements (or replace existing elements). erase, resize and destruction all involve destroying elements. If you had a type T that was not destructible, and attempted to instantiate a vector (say), I would expect that it would fail to compile.

As for the duplicate requirements, I suspect that's just something that snuck in when the CppReference folks wrote that page. The container requirements in the standard mention (in the entry for a == b) that the elements must be equality comparable.

I'm not terribly familiar with your stack, so this is a high-level answer to hit on your "Why". There WILL be a more specific answer for you, somewhere down the pipe (e.g. someone that can confirm whether this thread is relevant).

While I'm no Spring Daisy (or Spring dev), you bind an expression to filmMono that resolves as the query select film.* from film..... You reference that expression four times, and it's resolved four times, in separate contexts. The ordering of the statements is likely a partially-successful attempt by the lib author to lazily evaluate the expression that you bound locally, such that it's able to batch the four accidentally identical queries. You most likely resolved this by collecting into an actual container, and then mapping on that container instead of the expression bound to filmMono.

In general, this situation is because the options available to library authors aren't good when the language doesn't natively support lazy evaluation. Because any operation might alter the dataset, the library author has to choose between:

• A, construct just enough scaffolding to fully record all resources needed, copy the dataset for any operations that need to mutate records in some way, and hope that they can detect any edge-cases that might leak the scaffolding when the resolved dataset was expected (getting this right is...hard).
• B, resolve each level of mapping as a query, for each context it appears in, lest any operations mutate the dataset in ways that might surprise the integrator (e.g. you).
• C, as above, except instead of duplicating the original request, just duplicate the data...at every step. Pass-by-copy gets real painful real fast on the JVM, and languages like Clojure and Scala handle this by just making the dev be very specific about whether they want to mutate in-place, or copy then mutate.

In your case, B made the most sense to the folks that wrote that lib. In fact, they apparently got close enough to A that they were able to batch all the queries that were produced by resolving the expression bound to filmMono (which are only accidentally identical), so color me a bit impressed.

Many access patterns can be rewritten to optimize for the resulting queries instead. Your milage may vary...wildly. Getting familiar with raw SQL, or else a special-purpose language like GraphQL, can give much more consistent results than relational mappers, but I'm ever more appreciative of good IDE support, and mixing domains like that often means giving up auto-complete, context highlighting, lang-server solution-proofs and linting.

Given that the scope of the question was "why did this happen?", even noting my lack of familiarity with your stack, the answer is "lazy evaluation in a language that doesn't natively support it is really hard."

The problem here is related to inlining. I do not understand it completly, but here is what I understand.

First we find that copy&pasting the definition of replicateM into the Submission 1 yields the same bad performance as Submission 2 (submission). However if we replace the INLINABLE pragma of replicateM with a NOINLINE pragma things work again (submission).

The INLINABLE pragma on replicateM is different from an INLINE pragma, the latter leading to more inlining than the former. Specifically here if we define replicateM in the same file Haskells heuristic for inlining decides to inline, but with replicateM from base it decides against inlining in this case even in the presence of the INLINABLE pragma.

sequenceA and traverse on the other hand both have INLINE pragmas leading to inlining. Taking a hint from the above experiment we can define a non-inlinable sequenceA and indead this makes Solution 2 work (submission).

To get the expiration time of a single domain, you can use the RSKOwner contract with the expirationTime method. You can query this contract to with the domain you are interested in.

On Mainnet, the contract’s address is 0x45d3E4fB311982a06ba52359d44cB4f5980e0ef1, which can be verified on the RSK explorer. The ABI for this contract can be found here.

Using Web3 library, you can query a single domain (such as testing.rsk) like this:

As mentioned in the comments above, it was resolved after moved the service to run on a separate process (by specifying service with android:process in manifest)

I think this is a bit more efficient:

It completely depends on your application structure and also on how often you are going to query in subcollections or querying the whole collection or structuring your data with private/public fields to grant access to specific users. However both approaches have their own tradeoffs like 1 write per second per document or 1mb size of the document etc. What I would suggest is to think of your queries first and to design your database to best handle the queries you need to perform. I would suggest to review the following documents on Data structure and Data model. If you wanna more about security I would suggest to have a look at the documentation on security.

You can write your own version of takewhile where the predicate takes both the current and previous values: