I want to get only the nodes if one certain predicate is undefined.
Golang default values don't get stored as of now, and changing the current DGraph configuration would be pretty difficult.
I could filter them in the code afterwards, but I would appreciate a better solution.
Related
VS Codium allows users to configure options by using their name in a config file. However, it's not always obvious what the supported values are for a given name, and it's not always spelled out in the documentation either.
For example, the option security.workspace.trust.banner. I imagine this can be set to always or never, but I have no way of knowing for sure (without tedious trial and error). Note that the question is not about security.workspace.trust.banner but about finding out the legal values of any option.
Is there a reliable way to find out what exact values are acceptable for an option, given its name, for every option? Or do you ultimately have to guess?
I successfully managed to use field_weights in Sphinx to get the relevance I needed. However my fields are actually inclusive of several html tags (e.g. <Author> and <Description>). I need those in one field because of some other config work I am doing. So the field_weights won't in fact work for me. What I need is a way to weight the ZONES I set up in sphinx. However zone_weights is not working for me.
Well no, there are no explicit zone weights.
Can perhaps use the individual boost modifier to boost words, that are also within the zone...
ZONE:(h3) banada^1.234
While playing with mognodb console help, I found a db.getSisterDB() method.
And I am curious what is the purpose of this method. Looking through mongodb documentation and a quick google search did not yield satisfactory results.
By typing db.getSisterDb.help generates an error and typing db.getSisterDB gives the following definition of this method:
function ( name ){
return this.getMongo().getDB( name );
}
which suggests that this is just a wrapper around getDB. My suggestion that it is used in to access databases in a replica set, but I would like to listen to a person who can give me a more thorough explanation.
In the shell, db is a reference to the current database. If you want to query against a different DB in the same mongod instance, the way to get a proper reference to it would be to use this method (which has an alias, more gender neutral getSiblingDB).
If you wanted to use the longer syntax, you could: db.getMongo().getDB(name) gets you the same thing as db.getSiblingDB(name) or db.getSisterDB(name) but the former is longer to type.
All of the above work the same way in standalone mongod as well as replica sets (and sharded clusters).
Im going to add to the accepted answer because I did not find what I wanted as a first result.
getSiblingDB exists for scripting, where the use helper is not available
getSiblingDB is the newer between the identical getSisterDB, so use sibling as getSisterDB is no longer in documentation
when used in the shell, getSiblingDB serves the purpose of getting a database without changing the db variable
I'm attempting to write up a Yesod app as a replacement for a Ruby JSON service that uses MongoDB on the backend and I'm running into some snags.
the sql=foobar syntax in the models file does not seem too affect which collection Persistent.MongoDB uses. How can I change that?
is there a way to easily configure mongodb (preferably through the yaml file) to be explicitly read only? I'd take more comfort deploying this knowing that there was no possible way the app could overwrite or damage production data.
Is there any way I can get Persistent.MongoDB to ignore fields it doesn't know about? This service only needs a fraction of the fields in the collection in question. In order to keep the code as simple as possible, I'd really like to just map to the fields I care about and have Yesod ignore everything else. Instead it complains that the fields don't match.
How does one go about defining instances for models, such as ToJSON. I'd like to customize how that JSON gets rendered but I get the following error:
Handler/ProductStat.hs:8:10:
Illegal instance declaration for ToJSON Product'
(All instance types must be of the form (T t1 ... tn)
where T is not a synonym.
Use -XTypeSynonymInstances if you want to disable this.)
In the instance declaration forToJSON Product'
1) seems that sql= is not hooked up to mongo. Since sql is already doing this it shouldn't be difficult for Mongo.
2) you can change the function that runs the queries
in persistent/persistent-mongoDB/Database/Persist there is a runPool function of PersistConfig. That gets used in yesod-defaults. We should probably change the loadConfig function to check a readOnly setting
3) I am ok with changing the reorder function to allow for ignoring, although in the future (if MongoDB returns everything in ordeR) that may have performance implications, so ideally you would list the ignored columns.
4) This shouldn't require changes to Persistent. Did you try turning on TypeSynonymInstances ?
I have several other Yesod/Persistent priorities to attend to before these changes- please roll up your sleeves and let me know what help you need making them. I can change 2 & 3 myself fairly soon if you are committed to testing them.
What's the best way to keep track of unique tags for a collection of documents millions of items large? The normal way of doing tagging seems to be indexing multikeys. I will frequently need to get all the unique keys, though. I don't have access to mongodb's new "distinct" command, either, since my driver, erlmongo, doesn't seem to implement it, yet.
Even if your driver doesn't implement distinct, you can implement it yourself. In JavaScript (sorry, I don't know Erlang, but it should translate pretty directly) can say:
result = db.$cmd.findOne({"distinct" : "collection_name", "key" : "tags"})
So, that is: you do a findOne on the "$cmd" collection of whatever database you're using. Pass it the collection name and the key you want to run distinct on.
If you ever need a command your driver doesn't provide a helper for, you can look at http://www.mongodb.org/display/DOCS/List+of+Database+Commands for a somewhat complete list of database commands.
I know this is an old question, but I had the same issue and could not find a real solution in PHP for it.
So I came up with this:
http://snipplr.com/view/59334/list-of-keys-used-in-mongodb-collection/
John, you may find it useful to use Variety, an open source tool for analyzing a collection's schema: https://github.com/jamescropcho/variety
Perhaps you could run Variety every N hours in the background, and query the newly-created varietyResults database to retrieve a listing of unique keys which begin with a given string (i.e. are descendants of a specific parent).
Let me know if you have any questions, or need additional advice.
Good luck!