Is it possible to insert a new document into a Couchbase bucket without specifying the document's ID? I would like use Couchbase's Java SDK create a document and have Couchbase determine the document's UUID with Groovy code similar to the following:
import com.couchbase.client.java.CouchbaseCluster
import com.couchbase.client.java.Cluster
import com.couchbase.client.java.Bucket
import com.couchbase.client.java.document.JsonDocument
// Connect to localhost
CouchbaseCluster myCluster = CouchbaseCluster.create()
// Connect to a specific bucket
Bucket myBucket = myCluster.openBucket("default")
// Build the document
JsonObject person = JsonObject.empty()
.put("firstname", "Stephen")
.put("lastname", "Curry")
.put("twitterHandle", "#StephenCurry30")
.put("title", "First Unanimous NBA MVP)
// Create the document
JsonDocument stored = myBucket.upsert(JsonDocument.create(person));
No, Couchbase documents have to have a key, that's the whole point of a key-value store, after all. However, if you don't care what the key is, for example, because you retrieve documents through queries rather than by key, you can just use a uuid or any other unique value when creating the document.
It seems there is no way to have Couchbase generate the document IDs for me. At the suggestion of another developer, I am using UUID.randomUUID() to generate the document IDs in my application. The approach is working well for me so far.
Reference: https://forums.couchbase.com/t/create-a-couchbase-document-without-specifying-an-id/8243/4
As you already found out, generating a UUID is one approach.
If you want to generate a more meaningful ID, for instance a "foo" prefix followed by a sequence number, you can make use of atomic counters in Couchbase.
The atomic counter is a document that contains a long, on which the SDK relies to guarantee a unique, incremented value each time you call bucket.counter("counterKey", 1, 2). This code would take the value of the counter document "counterKey", increment it by 1 atomically and return the incremented value. If the counter doesn't exist, it is created with the initial value 2, which is the value returned.
This is not automatic, but a Couchbase way of creating sequences / IDs.
Related
I have a chat module coded in Nodejs and Redis, which loads all the DB users into Redis and later retrieve them with the Key and Value, As what redis server is expected to do,
To store them I used "Key" as the User_ID with prefix and values in json as below,
entry.user_id = rows[i].user_id;
entry.uname = rows[i].uname.toString();
client.set('chat_userid_' + entry.user_id, JSON.stringify(entry));
This works fine, as long as we do searches for the user's data using only the User_ID. Sometimes I have to find user with the "name" as well, In this case, when we want to search via name, I had to do another key to the value list just for that search.
entry.user_id = rows[i].user_id;
entry.uname = rows[i].uname.toString();
client.set('chat_uname_' + entry.uname, JSON.stringify(entry));
As you can see above Data structure is very low performance and redundant, Is there a better data structure to store the user data in the Redis server, that we can get the same result as per the above use-case?
We have a lot of docs in Couchbase with expiration = 0, which means that documents stay in Couchbase forever. I am aware that INSERT/UPDATE/DELETE isn't supported by N1QL.
We have 500,000,000 such docs and I would like to do this in parallel using chunks/bulks. How can I update the expiration field using Python 3?
I am trying this:
bucket.touch_multi(('000c4894abc23031eed1e8dda9e3b120', '000f311ea801638b5aba8c8405faea47'), ttl=10)
However I am getting an error like:
_NotFoundError_0xD (generated, catch NotFoundError): <Key=u'000c4894abc23031eed1e8dda9e3b120'
I just tried this:
from couchbase.cluster import Cluster
from couchbase.cluster import PasswordAuthenticator
cluster = Cluster('couchbase://localhost')
authenticator = PasswordAuthenticator('Administrator', 'password')
cluster.authenticate(authenticator)
cb = cluster.open_bucket('default')
keys = []
for i in range(10):
keys.append("key_{}".format(i))
for key in keys:
cb.upsert(key, {"some":"thing"})
print(cb.touch_multi(keys, ttl=5))
and I get no errors, just a dictionary of keys and OperationResults. And they do in fact expire soon thereafter. I'd guess some of your keys are not there.
However maybe you'd really rather set a bucket expiry? That will make all the documents expire in that time, regardless of what the expiry on the individual documents are. In addition to the above answer that mentions that, check out this for more details.
You can use Couchbase Python (Any) SDK Bucket.touch() method Described here https://docs.couchbase.com/python-sdk/current/document-operations.html#modifying-expiraton
If you don't know the document keys you can use N1QL Covered index get the document keys asynchronously inside your python SDK and use the above bucket touch API set expiration from your python SDK.
CREATE INDEX ix1 ON bucket(META().id) WHERE META().expiration = 0;
SELECT RAW META().id
FROM bucket WHERE META().expiration = 0 AND META().id LIKE "a%";
You can issue different SELECT's for different ranges and do in parallel.
Update Operation, You need to write one. As you get each key do (instead of update) bucket.touch(), which only updates document expiration without modifying the actual document. That saves get/put of whole document (https://docs.couchbase.com/python-sdk/current/core-operations.html#setting-document-expiration).
Whenever we save data to the database, there is always a corresponding ID which we use to fetch the data from that specific column.
sql_con.execute("SELECT FROM DBNAME WHERE ID = ?", id)
The above code only allows us to fetch data based from the ID. The problem is that the above code only accepts 1 supplied binding. In my database, I used sets of strings as the ID for each column, which means that the binding of my IDs are more than 1. And, those sets of strings have different bindings (or character count).
How do I modify the code in above, so I could input strings as my ID, preventing it from receiving the specific error:
sqlite3.ProgrammingError: Incorrect number of bindings supplied. The current statement uses 1, and there are 8 supplied.
Thank you in advance. I use Python 3.xx and in-built module sqlite3. Database is in .db file format and is a disk-based database.
I found the answer for my own question, by asking someone else.
For you to resolve this problem with the bindings of the input, just simply convert the parameter into a tuple.
OLD CODE:
sql_con.execute("SELECT FROM DBNAME WHERE ID = ?", id)
INTO THIS...
NEW CODE:
sql_con.execute("SELECT * FROM DBNAME WHERE ID = ?", (id,))
Hope it helps.
I have a use case where I have to remove a subset of entities stored in couchbase, e.g. removing all entities with keys starting with "pii_".
I am using NodeJS SDK but there is only one remove method which takes one key at a time: http://docs.couchbase.com/sdk-api/couchbase-node-client-2.0.0/Bucket.html#remove
In some cases thousands of entities need to be deleted and it takes very long time if I delete them one by one especially because I don't keep list of keys in my application.
I agree with the #ThinkFloyd when he saying: Delete on server should be delete on server, rather than requiring three steps like get data from server, iterate over it on client side and finally for each record fire delete on the server again.
In this regards, I think old fashioned RDBMS were better all you need to do is 'DELETE * from database where something=something'.
Fortunately, there is something similar to SQL is available in CouchBase called N1QL (pronounced nickle). I am not aware about JavaScript (and other language syntax) but this is how I did it in python.
Query to be used: DELETE from <bucketname> b where META(b).id LIKE "%"
layer_name_prefix = cb_layer_key + "|" + "%"
query = ""
try:
query = N1QLQuery('DELETE from `test-feature` b where META(b).id LIKE $1', layer_name_prefix)
cb.n1ql_query(query).execute()
except CouchbaseError, e:
logger.exception(e)
To achieve the same thing: alternate query could be as below if you are storing 'type' and/or other meta data like 'parent_id'.
DELETE from <bucket_name> where type='Feature' and parent_id=8;
But I prefer to use first version of the query as it operates on key, and I believe Couchbase must have some internal indexes to operate/query faster on key (and other metadata).
The best way to accomplish this is to create a Couchbase view by key and then range query over that view via your NodeJS code, making deletes on the results.
http://docs.couchbase.com/admin/admin/Views/views-querySample.html
http://docs.couchbase.com/couchbase-manual-2.0/#couchbase-views-writing-querying-selection-partial
http://docs.couchbase.com/sdk-api/couchbase-node-client-2.0.8/ViewQuery.html
For example, your Couchbase view could look like the following:
function(doc, meta) {
emit(meta.id, null);
}
Then in your NodeJS code, you could have something that looks like this:
var couchbase = require('couchbase');
var ViewQuery = couchbase.ViewQuery;
var query = ViewQuery.from('designdoc', 'by_id');
query.range("pii_", "pii_" + "\u0000", false);
var myBucket = myCluster.openBucket();
myBucket.query(query, function(err, results) {
for(i in results) {
// Delete code in here
}
});
Of course your Couchbase design document and view will be named differently than the example that I gave, but the important part is the ViewQuery.range function that was used.
All document ids prefixed with pii_ would be returned, in which case you can loop over them and start deleting.
Best,
I have been exclusively using cypher queries of this client for Neo4j because there is no out of the box way of doing many things. One of those id to get nodes. There is no way to retrieve them without knowing their id, which is very low level. Any idea on how to run a
$client->findOne('property','value');
?
It should be straightforward but it isn't from the documentation.
Make Indexes on the properties you want to search, from a newly created $personNode
$personIndex = new \Everyman\Neo4j\NodeIndex($client, 'person');
$personIndex->add($personNode, 'name', $personNode->name);
Then later to search, the new PHP object $personIndex will reference the same, populated index as above.
$personIndex = new \Everyman\Neo4j\NodeIndex($client, 'person');
$match = $personIndex->findOne('name', 'edoceo');