Peer (Datomic Java API Documentation)

java.lang.Object
- datomic.Peer

```
public class Peer
extends java.lang.Object
```
Main entry point, used to manage connections, submit transactions, and query.

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static java.lang.Object`	`administerSystem(java.util.Map options)` Administer a Datomic system.
`static void`	`cancel(java.lang.Object anomaly)` Cancels the current Datomic operation (query or transaction).
`static Connection`	`connect(java.lang.Object uriOrMap)` Connects to the specified database.
`static boolean`	`createDatabase(java.lang.Object uriOrMap)` Creates a database with the given name.
`static boolean`	`deleteDatabase(java.lang.Object uriOrMap)` Deletes a database.
`static datomic.functions.Fn`	`function(java.util.Map m)` Generates a function object given a map of :lang - clojure or java :params - a list of parameter names used in the code :code - a string containing the code of the function body.
`static java.util.List<java.lang.String>`	`getDatabaseNames(java.lang.Object uriOrMap)` Returns a list of database names.
`static java.lang.Object`	`part(java.lang.Object entityId)` Returns the partition of this entity id.
`static java.util.Collection<java.util.List<java.lang.Object>>`	`q(java.lang.Object query, java.lang.Object... inputs)` Like `query(Object, Object...)`, but with a more specific return signature.
`static java.util.stream.Stream<java.lang.Object>`	`qseq(java.lang.Object query, java.lang.Object... inputs)` Performs the query described by `query` and `inputs` (as per `query(Object, Object...)`), Item transformations such as pull are deferred until the Stream is consumed.
`static <T> T`	`query(java.lang.Object query, java.lang.Object... inputs)` Executes a datalog query.
`static <T> T`	`query(QueryRequest queryRequest)` Like `query(Object, Object...)`, but accepts a `QueryRequest` object.
`static boolean`	`renameDatabase(java.lang.Object uriOrMap, java.lang.String newName)` Renames a database.
`static java.lang.Object`	`resolveTempid(Database db, java.lang.Object tempids, java.lang.Object tempid)` Resolve a tempid to the actual id assigned in a database.
`static void`	`shutdown(boolean shutdownClojure)` Shutdown all peer resources.
`static java.util.UUID`	`squuid()` Constructs a semi-sequential UUID.
`static long`	`squuidTimeMillis(java.util.UUID squuid)` Get the time component of a squuid.
`static java.lang.Object`	`tempid(java.lang.Object partition)` Generates a temp id in the designated partition.
`static java.lang.Object`	`tempid(java.lang.Object partition, long idNumber)` Generates a temp id in the designated partition.
`static long`	`toT(java.lang.Object tx)` Returns the t value associated with this tx.
`static java.lang.Object`	`toTx(long t)` Returns the tx associated with this t value.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - connect
```
public static Connection connect(java.lang.Object uriOrMap)
```
    Connects to the specified database. The systemId and credentials are defined when a new Datomic instance is provisioned.
    URI syntax:
```
 ;;dynamo using roles
 datomic:ddb://{aws-region}/{dynamodb-table}/{db-name}

 ;;dynamo using keys, use roles if possible
 datomic:ddb://{aws-region}/{dynamodb-table}/{db-name}?aws_access_key_id={XXX}&aws_secret_key={YYY}

 ;; dynamo local
 datomic:ddb-local://{endpoint}:{port}/{dynamodb-table}/{db-name}?aws_access_key_id={XXX}&aws_secret_key={YYY}

 ;;riak, defaults to protobuf
 datomic:riak://{host}[:{port}]/{bucket}/{dbname}[?interface=http|https|protobuf]

 ;; couchbase
 datomic:couchbase://{host}/{bucket}/{dbname}[?password={xxx}]

 ;; sql
 datomic:sql://{db-name}?{jdbc-url}

 ;; infinispan
 datomic:inf://{cluster-member-host}:{port}/{db-name}

 ;; cassandra
 datomic:cass://{cluster-member-host}[:{port}]/{keyspace}.{table}/{db-name}[?user={user}&password={pwd}][&ssl=true]

 ;; dev appliance
 datomic:dev://{transactor-host}:{port}/{db-name}[?password={password}]

 ;; limited-edition transactor integrated storage
 datomic:limited-edition://{transactor-host}:{port}/{db-name}[?password={password}]

 ;; in-process memory
 datomic:mem://{db-name}
 
```
    Note that URIs must be percent encoded and db-name cannot contain the following characters: / " * : = ?
    The dev, free, and limited-edition protocols use an additional ports to communicate with storage. By default this port is one higher than the specified transactor port. You can override the default by specifying h2-port in the query string, e.g.
```
 datomic:limited-edition://localhost:4334/mydb?h2-port=6000&
 
```
    The sql protocol also supports a map format for the connection params. This is to enable communicating objects that can't be embedded in URI strings, like DataSources. The format for the map is:
```
     {
     :protocol :sql
     :db-name "myDb"

     :data-source aDataSourceObject
     ;; OR
     :factory aCallableReturningConnection
     }
 
```
    Note only one of data-source or factory should be supplied. The keys and protocol name can be keywords or strings. The cass protocol also supports a map format for the connection params. The format for the map is:
```
     {
     :protocol :cass
     :db-name "myDb"
     :table "myKeyspace.myTable"

     :cluster aClusterObject
     }
 
```
    Note aClusterObject must be an instance of type com.datastax.driver.core.Cluster. The keys and protocol name can be keywords or strings. Datomic connections do not adhere to an acquire/use/release pattern. They are thread-safe and long lived. Connections are cached such that calling Peer.connect(uri) multiple times with the same URI value will return the same connection object.
    Parameters:
    
    uriOrMap - a Datomic connection URI string, or parameters map if supported by the protocol.
    
    Returns:
    
    a connection to the database.
  - createDatabase
```
public static boolean createDatabase(java.lang.Object uriOrMap)
```
    Creates a database with the given name. The systemId and credentials are defined when a new Datomic instance is provisioned. Idempotent.
    Parameters:
    
    uriOrMap - the uri of the database to create.
    
    Returns:
    true
    if the database was created,
    false
    if the database already exists.
  - renameDatabase
```
public static boolean renameDatabase(java.lang.Object uriOrMap,
                                     java.lang.String newName)
```
    Renames a database.
    Parameters:
    
    uriOrMap - same as in #connect(Object)
    
    newName - the new name of the database. This is the database name only and should not be a URI.
    
    Returns:
    true
    if rename succeeded
  - deleteDatabase
```
public static boolean deleteDatabase(java.lang.Object uriOrMap)
```
    Deletes a database.
    Parameters:
    
    uriOrMap - same as in #connect(Object)
    
    Returns:
    true
    if delete occurred.
  - getDatabaseNames
```
public static java.util.List<java.lang.String> getDatabaseNames(java.lang.Object uriOrMap)
```
    Returns a list of database names. URI is a database URI as described in the connect(java.lang.Object) documentation, but with a '*' where the database name would be. For instance:
```
   datomic:dev://{transactor-host}:{port}/*
 
```
    When using the map form, :db-name should be omitted.
    Parameters:
    
    uriOrMap - same as in #connect(Object), with a '*' where the database name would be, or omitted in the map form.
    
    Returns:
    
    List of database names.
    
    Since:
    
    0.9.5040
  - administerSystem
```
public static java.lang.Object administerSystem(java.util.Map options)
```
    Administer a Datomic system. Throws if operation fails.
    
    Parameters:
    
    options - Map
    
    Returns:
    
    data describing the operation result
    
    Since:
    
    0.9.5893
  - squuid
```
public static java.util.UUID squuid()
```
    Constructs a semi-sequential UUID. Useful for creating UUIDs that don't fragment indexes.
    
    Returns:
    
    a UUID whose most significant 32 bits are currentTimeMillis rounded to seconds
    
    Since:
    
    0.8.3343
  - squuidTimeMillis
```
public static long squuidTimeMillis(java.util.UUID squuid)
```
    Get the time component of a squuid.
    
    Parameters:
    
    squuid - a UUID created by squuid()
    
    Returns:
    
    the time in the format of System.currentTimeMillis
    
    Since:
    
    0.8.3343
  - tempid
```
public static java.lang.Object tempid(java.lang.Object partition)
```
    Generates a temp id in the designated partition.
    
    Parameters:
    
    partition - a keyword identifying the partition.
    
    Returns:
    
    a temp id
  - tempid
```
public static java.lang.Object tempid(java.lang.Object partition,
                                      long idNumber)
```
    Generates a temp id in the designated partition. Values of idNumber from -1 (inclusive) to -1000000 (exclusive) are reserved for user-created temp ids.
    
    Parameters:
    
    partition - - a keyword identifying the partition.
    
    idNumber - - a long in the range (-1000000,-1]
    
    Returns:
    
    a temp id
  - toT
```
public static long toT(java.lang.Object tx)
```
    Returns the t value associated with this tx.
    
    Parameters:
    
    tx - a tx
    
    Returns:
    
    a t value
    
    Since:
    
    0.8.3372
  - toTx
```
public static java.lang.Object toTx(long t)
```
    Returns the tx associated with this t value.
    
    Parameters:
    
    t - a t value
    
    Returns:
    
    a tx
    
    Since:
    
    0.8.3372
  - part
```
public static java.lang.Object part(java.lang.Object entityId)
```
    Returns the partition of this entity id.
    
    Parameters:
    
    entityId - an entityId
    
    Returns:
    
    a partition
    
    Since:
    
    0.8.3372
  - q
```
public static java.util.Collection<java.util.List<java.lang.Object>> q(java.lang.Object query,
                                                                       java.lang.Object... inputs)
```
    Like query(Object, Object...), but with a more specific return signature. Supports same grammar as query, except for find-coll, find-scalar, and find-tuple.
  - query
```
public static <T> T query(java.lang.Object query,
                          java.lang.Object... inputs)
```
    Executes a datalog query.
    In addition to basic pattern matching, query supports
    - joins
    - rules
    - arbitrary predicates and functions
    - aggregates
    - binding options for inputs
    - find specification for outputs
    - pull patterns
    Query can be applied to multiple inputs, including both databases and plain old data. See the grammar and documentation for complete details.
    Query runs locally in a Peer process. Query is set-based: intermediate and final result sets must fit in memory. The query data structure passed in can be one of
    - a map that may include :find, :with, :in, and :where keys
    - a list representation of that same map
    - a serialized edn string of the list or map form
    The inputs can be any of
    - database values
    - arbitrary values
    - rules
    - pull patterns
    If a single database value is provided as input, then no :in section is required in the query.
    Type Parameters:
    
    T - a type compatible with the find specification
    
    Parameters:
    
    query - a data structure describing the query
    
    inputs - inputs bound to the names in :in section of query
    
    Returns:
    
    a data structure based on the find specification
    
    Since:
    
    0.9.5040
  - query
```
public static <T> T query(QueryRequest queryRequest)
```
    Like query(Object, Object...), but accepts a QueryRequest object.
    
    Since:
    
    0.9.5153
  - qseq
```
public static java.util.stream.Stream<java.lang.Object> qseq(java.lang.Object query,
                                                             java.lang.Object... inputs)
```
    Performs the query described by query and inputs (as per query(Object, Object...)), Item transformations such as pull are deferred until the Stream is consumed. For queries with pull(s), this results in:
    - reduced memory use and the ability to execute larger queries
    - lower latency before the first results are returned
    Parameters:
    
    query - a data structure describing the query
    
    inputs - inputs bound to the names in :in section of query
    
    Returns:
    
    a Stream of the data structure based on the find specification
    
    Since:
    
    0.9.6110
  - function
```
public static datomic.functions.Fn function(java.util.Map m)
```
    Generates a function object given a map of :lang - clojure or java :params - a list of parameter names used in the code :code - a string containing the code of the function body. :code should be the body of a method corresponding to the params, which will be Objects, but can begin with one or more import statements.
    
    Parameters:
    
    m - a map defining the function
    
    Returns:
    
    a function object implementing Fn plus one of FnN corresponding to its arity.
  - resolveTempid
```
public static java.lang.Object resolveTempid(Database db,
                                             java.lang.Object tempids,
                                             java.lang.Object tempid)
```
    Resolve a tempid to the actual id assigned in a database.
    
    Parameters:
    
    db - a database
    
    tempids - Connection.TEMPIDS member of a map returned from Connection.transact(java.util.List) or Connection.transactAsync.
    
    tempid - a tempid
    
    Returns:
    
    the actual id corresponding to tempid
  - shutdown
```
public static void shutdown(boolean shutdownClojure)
```
    Shutdown all peer resources. This method should be called as part of clean shutdown of a JVM process. Will release all Connections, and, if shutdownClojure is true, will release Clojure resources. Programs written in Clojure can set shutdownClojure to false if they manage Clojure resources (e.g. agents) outside of Datomic; programs written in other JVM languages should typically set shutdownClojure to true.
    
    Parameters:
    
    shutdownClojure - set true to shutdown Clojure resources
    
    Since:
    
    0.8.3861
  - cancel
```
public static void cancel(java.lang.Object anomaly)
```
    Cancels the current Datomic operation (query or transaction). Throws an ex-info with an anomaly to the original caller. anomaly is as described by https://github.com/cognitect-labs/anomalies. :cognitect.anomalies/category is a required key, valid values are: :cognitect.anomalies/incorrect :cognitect.anomalies/conflict When :cognitect.anomalies/message is provided, the message will be used as the Exception's detail message Other keys should be namespace-qualified. All data passed to cancel must be fressian-serializable.
    
    Parameters:
    
    anomaly - Map

Class Peer

Method Summary

Methods inherited from class java.lang.Object

Method Detail

connect

createDatabase

renameDatabase

deleteDatabase

getDatabaseNames

administerSystem

squuid

squuidTimeMillis

tempid

tempid

toT

toTx

part

q

query

query

qseq

function

resolveTempid

shutdown

cancel