Couchbase API数据访问Guide

jieforest

Set Operations

The set method stores a value to the database with a specified key, overwriting existing content if it exists (see add/replace above).

1. client.set(key, value, options = {})
   
2. client.set[key, options = {}] = value

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options:

1. :ttl         [Fixnum, Integer] Time to Live in seconds [optional]
   
2. :flags       [Fixnum] Flags that you want to store/retrieve [optional]
   
3. :cas         [Fixnum] Optimistic locking for update control, must match the document cas in Couchbase to succeed
   
4. :format      [:document, :plain, :marshal] Explicit format setting, :plain for strings, :document for Hash(JSON), :marshal to use Marshal. load and Marshal.dump; format is :document by default

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jieforest

Simple Get Operations

1. val = client.get(key, options = {})
   
2. val = client[“key”]

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Extended Tuple Get Operations

1. val, flags, cas = client.get(key, :extended => true)
   
2. val, flags, cas = client[“key”, :extended => true]

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jieforest

Multi-Get Operations

1. val_array = client.get(keys)
   
2. val_hash = client.get(keys, :assemble_hash => true)

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options:

1. :extended         [String, Symbol] Key used to reference the value
   
2. :quiet            [true, false] Return nil for missing keys default, or false to Return Couchbase::Error::KeyNotFound for missing key
   
3. :ttl              [Fixnum, Integer] Get and Touch, :ttl will also reset the TTL at the same time as the get (seconds)
   
4. :lock             Lock the document, true to use default lock timeout, or integer for number of seconds to lock
   
5. :format           [:document, :plain, :marshal] Explicit format setting, :plain for strings, :document for Hash(JSON), :marshal to use Marshal.load and Marshal.dump
   
6. :assemble_hash    [true, false] For Multi-Get, will return a Hash keyed on the document keys instead of default of array

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jieforest

GETTING STATS FROM COUCHBASE

Obtain stats from all servers for the connection (bucket)

1. client.stats
   
2. client.stats[“stats”]

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To fetch memory stats

1. client.stats(:memory)

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Parameters:

1. stat Individual stat string (i.e. "curr_items")

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jieforest

DELETING AND UPDATING DATA

To delete keys/values

1. client.delete(key)

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Atomic Counter Operations

Atomic Counters are only atomic per cluster, but are useful for many different patterns and numeric data. They are unsigned positive integers.

You cannot use atomic operations on floats or objects or arrays.

1. client.incr(key, delta, options = {})
   
2. client.decr(key, delta, options = {})

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jieforest

options:

1. delta        [Fixnum] Amount to incr/decr, default is 1, can be up to 64 bits
   
2. :create      [true, false] If set to true, if key doesn’t exist, initializes to zero but doesn’t increment, can be combined with :initial
   
3. :initial     [Fixnum, Unsigned Integer] Sets initial value if key doesn’t exist, doesn’t increment the initial value!
   
4. :extended    [true, false] Returns [value, cas] tuple instead of just value
   
5. :ttl         [Fixnum, Integer] Sets TTL, doesn’t alter existing TTL, will only be applied to a new item created via :create and/or :initial

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Touch Operations

Reset the TTL expiration on one or more keys explicitly with the touch command, can also be done with a get command.

1. client.touch(key, ttl)
   
2. client.touch({“key1”=> ttl1, “key2” => ttl2})

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jieforest

Durability Requirements

Observe the state of the keys on all the nodes or using :replicated and ersisted it allows to set up the waiting rule.

1. client.observe(*keys, options = {})
   
2. client.observe_and_wait(*keys, options = {})
   

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Non-JSON Operations

For non-json values, prepend and append can concatenate to existing values accordingly. Defaults tolain format for encoder/decoder.

1. client.prepend(key, value)
   
2. client.append(key, value)

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jieforest

QUERYING DATA

With Couchbase Server 2.0, you can create Indexes through Map/Reduce functions.

http://www.couchbase.com/docs/co ... ouchbase-views.html

Create Design Doc Object

Refer to the design_doc by name, the Views are an array of view names, as well as functions defined by name.

1. ddoc = client.design_docs[‘design_doc_name’]
   
2. ddoc.views #=> [‘view_name’, ‘view_name_2’, …]

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Use dot notation for accessing the view by your defined view name and pass in options for query parameters:

1. ddoc.view_name(params = {}).each do |doc|
   
2. # do stuff with docs
   
3. end

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jieforest

options:

1. :include_docs        [true, false] Perform get with key on rows returned with key (non-reduce)
   
2. :descending          [true, false], reverse order of returned rows
   
3. :key                 [String, Fixnum, Hash, Array] Return only rows with index key that match :key, simple and compound keys can be used (JSON encoded)
   
4. :keys                [Array] Return only rows that match array of keys (see :key), both simple and compound keys (JSON encoded)
   
5. :startkey            [String, Fixnum, Hash, Array] Range query from :start_key to :end_key (JSON encoded)
   
6. :endkey              [String, Fixnum, Hash, Array] Range query from :start_key to :end_key (JSON encoded)
   
7. :startkey_docid      [String] Document id to start with (to allow pagination for duplicate startkeys
   
8. :endkey_docid        [String] Last document id to include in the output (to allow pagination for duplicate startkeys)
   
9. :inclusive_end       [true, false] If true, specificed end key is included in result
   
10. :limit               [Fixnum] Limit the results returned
    
11. :skip                [Fixnum] Skip a number of results before returning (can be used with :limit to page through results)
    
12. :reduce              [true, false] Perform the reduce function defined in the view. If there is no reduce defined default is false and setting to true will return error.
    
13. :group               [true, false] Groups results using the view defined reduce function
    
14. :group_level         [Fixnum] Sets the grouping level for compound keys
    
15. :stale               [:false, :update_after, :ok] Consistency setting, :false initiates Design Document to update indexes before returning results, :update_after updates indexes after returning results, :ok doesn’t trigger indexers and returns existing indexed results
    
16. :body                [Hash] Takes same parameters as options but does it as a POST if the query has many parameters or is complex
    
17. :on_error            [:continue, :stop] Behavior setting if an error occurs during view query

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jieforest

.NET CONNECTING TO COUCHBASE

1. var config = new CouchbaseClientConfiguration();
   
2. config.Urls.Add(new Uri(“http://<hostname>:8091/pools/”));
   
3. config.Bucket = “<bucketname>”;
   
4. var client = new CouchbaseClient(config);

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WRITING DATA

Based on the storemode, Store and ExecuteStore may be an Add, Replace or Set operation. Execute API’s return the operation result.

Store Operations

1. object.Store(storemode, key, value)
   
2. object.Store(storemode, key, value, validfor)
   
3. object.Store(storemode, key, value, expiresat)

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