trait AVET extends GenericNs
AVET Index.
"The AVET index provides efficient access to particular combinations of attribute and value." (from Datomic documentation)
Access the AVET Index in Molecule by instantiating an AVET object with one or more arguments and then add generic attributes:
// Create AVET Index molecule with 1 entity id argument AVET(":Person/age").e.v.t.get === List( (e1, 42, t2), (e2, 37, t5) (e3, 14, t7), ) // Narrow search with multiple arguments AVET(":Person/age", 42).e.t.get === List( (e1, t2) ) AVET(":Person/age", 42, e1).e.v.get === List( (e1, t2) ) AVET(":Person/age", 42, e1, t2).e.v.get === List( (e1, t2) )
The AVET Index can be filtered by a range of values between from
(inclusive) and
until
(exclusive) for an attribute:
AVET.range(":Person/age", Some(14), Some(37)).v.e.t.get === List( (14, e4, t7) // 14 is included in value range // 37 not included in value range // 42 outside value range ) // If `from` is None, the range starts from the beginning AVET.range(":Person/age", None, Some(40)).v.e.t.get === List( (14, e3, t7), (37, e2, t5), ) // If `until` is None, the range goes to the end AVET.range(":Person/age", Some(20), None).v.e.t.get === List( (37, e2, t5), (42, e1, t2) )
Index attributes available:
e
- Entity id (Long)a
- Full attribute name like ":Person/name" (String)v
- Value of Datoms (Any)t
- Transaction pointer (Long/Int)tx
- Transaction entity id (Long)txInstant
- Transaction wall clock time (java.util.Date)op
- Operation status: assertion (true) / retraction (false)
- Source
- AVET.scala
- Note
The Molecule Index API's don't allow returning the whole Index/the whole database. So omitting arguments constructing the Index object (like
AVET.a.v.e.t.get
) will throw an exception.
Please use Datomics API if you need to return the whole database Index:
conn.db.datoms(datomic.Database.AVET)
from
anduntil
cannot both be None since Molecule doesn't allow returning all datoms.- See also
Tests for more Index query examples.
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Type Members
-
final
class
a[Ns, In] extends OneString[Ns, In] with Indexed
(Partition)-Namespace-prefixed attribute name (":part_Ns/attr")
-
final
class
e[Ns, In] extends OneLong[Ns, In] with Indexed
Entity id (Long)
-
final
class
op[Ns, In] extends OneBoolean[Ns, In] with Indexed
Transaction operation: assertion (true) or retraction (false)
-
final
class
t[Ns, In] extends OneLong[Ns, In] with Indexed
Transaction point in time
t
(Long/Int) -
final
class
tx[Ns, In] extends OneLong[Ns, In] with Indexed
Transaction entity id (Long)
-
final
class
txInstant[Ns, In] extends OneDate[Ns, In] with Indexed
Transaction wall-clock time (Date)
-
final
class
v[Ns, In] extends OneAny[Ns, In] with Indexed
Datom value (Any)
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Documentation/API for the Molecule library - a meta DSL for the Datomic database.
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