Selective use of data structure operations for path query evaluation
The disclosed technologies are capable of selectively using data structure operations for path query evaluation. One technique involves reading a query that traverses at least two nodes and at least one edge of a graph in a graph database; compiling the query into a set of variables and a set of constraints, where the set of variables and the set of constraints correspond to the two nodes and the one edge of the graph; creating an in-memory data structure that comprises a table; using the set of variables and the set of constraints to determine an operation that is performable using the in-memory data structure; checking for an existence of a condition relating to the in-memory data structure or the operation; skipping the operation if the condition exists or executing the operation if the condition does not exist; and storing a set of intermediate query results in the table.
1. A method comprising:
reading a query that traverses at least two nodes and at least one edge of a graph in a graph database;
compiling the query into a set of variables and a set of constraints, the set of variables and the set of constraints corresponding to the at least two nodes and the at least one edge of the graph;
creating an in-memory data structure comprising at least one table;
using the set of variables and the set of constraints, determining an operation that is performable using the in-memory data structure;
checking for an existence of a condition relating to the in-memory data structure or the operation;
if the condition exists, skipping the operation;
if the condition does not exist, executing the operation;
storing a set of intermediate query results in the at least one table;
wherein checking for the existence of the condition comprises determining whether the in-memory data structure comprises a nested disjunction that includes at least one disjunctive child table that has zero rows;
if the in-memory data structure comprises a nested disjunction that includes at least one disjunctive child table that has zero rows, the condition exists and skipping the operation comprises skipping a path consistency checking operation; and
if the in-memory data structure does not comprise a nested disjunction that includes at least one disjunctive child table that has zero rows, the condition does not exist and executing the operation comprises executing a path consistency checking operation;
wherein the method is performed by at least one computing device.
2. The method of claim 1 , wherein checking for the existence of the condition comprises determining whether a variable of the set of variables is a single row variable.
3. The method of claim 2 , wherein, if the variable is a single row variable, the condition exists and skipping the operation comprises skipping a path consistency checking operation.
4. The method of claim 3 , further comprising reading the set of intermediate query results from a data storage.
5. The method of claim 1 , wherein checking for the existence of the condition comprises determining whether a variable of the set of variables is a multi-row variable.
6. The method of claim 5 , wherein, if the variable is a multi-row variable, the condition does not exist and executing the operation comprises executing a path consistency checking operation.
7. The method of claim 6 , further comprising executing the path consistency checking operation prior to reading the set of intermediate query results from a data storage.
8. The method of claim 1 , wherein checking for the existence of the condition comprises determining whether the operation is non-selective.
9. The method of claim 8 , wherein, if the operation is non-selective, the condition exists and skipping the operation comprises skipping a table creation operation.
10. The method of claim 9 , further comprising creating an execution head without executing the table creation operation.
11. The method of claim 1 , wherein checking for the existence of the condition comprises determining whether the operation is selective.
12. The method of claim 11 , wherein, if the operation is selective, the condition does not exist and executing the operation comprises executing a table creation operation.
13. The method of claim 12 , further comprising creating an execution head prior to executing the table creation operation.
14. At least one non-transitory machine-readable storage medium comprising instructions which, when implemented by at least one machine, cause the at least one machine to perform operations comprising:
reading a query that traverses at least two nodes and at least one edge of a graph in a graph database;
compiling the query into a set of variables and a set of constraints;
creating an in-memory data structure comprising at least one table;
using the set of variables and the set of constraints, determining an operation that is performable using the in-memory data structure;
checking for an existence of a condition relating to the in-memory data structure or the operation;
if the condition exists, skipping the operation;
storing a set of intermediate query results in the at least one table; and
if the condition does not exist, executing the operation;
wherein checking for the existence of the condition comprises:
determining whether a variable of the set of variables is a single row variable, and if the variable is a single row variable, the condition exists and skipping the operation comprises skipping a path consistency checking operation; or
determining whether a variable of the set of variables is a multi-row variable, and if the variable is a multi-row variable, the condition does not exist and executing the operation comprises executing a path consistency checking operation.
15. At least one non-transitory machine-readable storage medium comprising instructions which, when implemented by at least one machine, cause the at least one machine to perform operations comprising:
reading a query that traverses at least two nodes and at least one edge of a graph in a graph database;
compiling the query into a set of variables and a set of constraints;
creating an in-memory data structure comprising at least one table;
using the set of variables and the set of constraints, determining an operation that is performable using the in-memory data structure;
checking for an existence of a condition relating to the in-memory data structure or the operation;
if the condition exists, skipping the operation;
storing a set of intermediate query results in the at least one table; and
if the condition does not exist, executing the operation;
wherein checking for the existence of the condition comprises:
determining whether the operation is non-selective, and if the operation is non-selective, the condition exists and skipping the operation comprises skipping a table creation operation; or
determining whether the operation is selective, and if the operation is selective, the condition does not exist and executing the operation comprises executing a table creation operation.
16. At least one non-transitory machine-readable storage medium comprising instructions which, when implemented by at least one machine, cause the at least one machine to perform operations comprising:
reading a query that traverses at least two nodes and at least one edge of a graph in a graph database;
compiling the query into a set of variables and a set of constraints;
creating an in-memory data structure comprising at least one table;
using the set of variables and the set of constraints, determining an operation that is performable using the in-memory data structure;
checking for an existence of a condition relating to the in-memory data structure or the operation;
if the condition exists, skipping the operation;
storing a set of intermediate query results in the at least one table; and
if the condition does not exist, executing the operation;
wherein checking for the existence of the condition comprises:
determining whether the in-memory data structure comprises a nested disjunction that includes at least one disjunctive child table that has zero rows;
if the in-memory data structure comprises a nested disjunction that includes at least one disjunctive child table that has zero rows, the condition exists and skipping the operation comprises skipping a path consistency checking operation; or
if the in-memory data structure does not comprise a nested disjunction that includes at least one disjunctive child table that has zero rows, the condition does not exist and executing the operation comprises executing a path consistency checking operation.