BRANCHABLE GRAPH DATABASES
The disclosed embodiments provide a system for providing a graph database storing a graph. During operation, the system executes one or more processes for providing the graph database. Next, the system stores a sequence of changes to the graph in a base version of the graph database. The system then branches a version of the graph database from a virtual time in the base version. Finally, the system uses the branched version to process one or more queries of the graph database.
1 . A method, comprising:
executing, on a computer system, one or more processes for providing a graph database storing a graph, wherein the graph comprises a set of nodes, a set of edges between pairs of nodes in the set of nodes, and a set of predicates; and
maintaining, by the one or more processes, the graph database by:
storing a sequence of changes to the graph in a base version of the graph database;
branching a version of the graph database from a virtual time in the base version; and
using the branched version to process one or more queries of the graph database.
2 . The method of claim 1 , wherein using the branched version to process the one or more queries of the graph database comprises:
receiving a first query as a write request that comprises one or more additional changes to the graph; and
writing the one or more additional changes to the branched version.
3 . The method of claim 2 , wherein using the branched version to process the one or more queries of the graph database further comprises:
verifying a successful write of the one or more additional changes to the branched version; and
merging the one or more additional changes from the branched version into the base version.
4 . The method of claim 3 , wherein merging the one or more changes into the base version comprises:
appending the one or more additional changes to the sequence of changes in the base version.
5 . The method of claim 3 ,
wherein the one or more additional changes are written to the branched version during a user session; and
wherein the one or more additional changes are merged from the branched version into the base version at an end of the user session.
6 . The method of claim 2 , wherein using the branched version to process the one or more queries of the graph database further comprises:
receiving a second query as a read request; and
providing, in response to the second query, a result that comprises the one or more additional changes from the branched version and one or more changes from the base version that predate a creation of the branched version.
7 . The method of claim 2 , wherein the one or more additional changes comprise one or more temporary changes to the graph database.
8 . The method of claim 1 , wherein branching the version of the graph database from the virtual time in the base version comprises:
referencing, from the branched version, an offset in the base version that represents the virtual time; and
using the branched version to track an additional sequence of changes to the graph after the virtual time.
9 . The method of claim 1 , wherein using the branched version to process the one or more queries of the graph database comprises:
using the branched version to process read requests independently of updates to the sequence of changes in the base version.
10 . The method of claim 1 , wherein using the branched version to process one or more queries of the graph database comprises:
creating an index from the branched version; and
using the index to process the one or more queries.
11 . An apparatus, comprising:
one or more processors; and
memory storing instructions that, when executed by the one or more processors, cause the apparatus to:
execute one or more processes for providing a graph database storing a graph, wherein the graph comprises a set of nodes, a set of edges between pairs of nodes in the set of nodes, and a set of predicates;
store a sequence of changes to the graph in a base version of the graph database;
branch a version of the graph database from a virtual time in the base version; and
use the branched version to process one or more queries of the graph database.
12 . The apparatus of claim 11 , wherein using the branched version to process the one or more queries of the graph database comprises:
receiving a first query as a write request that comprises one or more additional changes to the graph; and
writing the one or more additional changes to the branched version.
13 . The apparatus of claim 12 , wherein using the branched version to process the one or more queries of the graph database further comprises:
verifying a successful write of the one or more additional changes to the branched version; and
merging the one or more additional changes from the branched version into the base version.
14 . The apparatus of claim 13 ,
wherein the one or more additional changes are written to the branched version during a user session, and
wherein the one or more additional changes are merged from the branched version into the base version at an end of the user session.
15 . The apparatus of claim 12 , wherein using the branched version to process the one or more queries of the graph database further comprises:
receiving a second query as a read request; and
providing, in response to the second query, a result that comprises the one or more additional changes from the branched version and one or more changes from the base version that predate a creation of the branched version.
16 . The apparatus of claim 12 , wherein the one or more additional changes comprise one or more temporary changes to the graph database.
17 . The apparatus of claim 11 , wherein branching the version of the graph database from the virtual time in the base version comprises:
referencing, from the branched version, an offset in the base version that represents the virtual time; and
using the branched version to track an additional sequence of changes to the graph after the virtual time.
18 . The apparatus of claim 11 , wherein using the branched version to process the one or more queries of the graph database comprises:
using the branched version to process read requests independently of updates to the sequence of changes in the base version.
19 . A system, comprising:
a management module comprising a non-transitory computer-readable medium comprising instructions that, when executed by one or more processors, cause the system to execute one or more processes for providing a graph database storing a graph, wherein the graph comprises a set of nodes, a set of edges between pairs of nodes in the set of nodes, and a set of predicates; and
a processing module comprising a non-transitory computer-readable medium comprising instructions that, when executed by the one or more processors, cause the system to maintain, by the one or more processes, the graph database by:
store a sequence of changes to the graph in a base version of the graph database;
branch a version of the graph database from a virtual time in the base version; and
use the branched version to process one or more queries of the graph database.
20 . The system of claim 19 , wherein branching the version of the graph database from the virtual time in the base version comprises:
referencing, from the branched version, an offset in the base version that represents the virtual time; and
using the branched version to track an additional sequence of changes to the graph after the virtual time.