5.7.1 Simple Property Graph Queries
The examples in this topic query vertices, edges, and properties of the graph.
Example 5-1 Find a Vertex with a Specified Vertex ID
This example find the vertex with vertex ID 1 in the connections graph.
SQL> select vid, k, v, vn, vt
from connectionsVT$
where vid=1;
The output might be as follows:
1 country United States
1 name Robert Smith
1 occupation CEO of Example Corporation
...
Example 5-2 Find an Edge with a Specified Edge ID
This example find the edge with edge ID 100 in the connections graph.
SQL> select eid,svid,dvid,k,t,v,vn,vt
from connectionsGE$
where eid=1000;
The output might be as follows:
1000 1 2 weight 3 1 1
In the preceding output, the K of the edge property is "weight" and the type ID of the value is 3, indicating a float value.
Example 5-3 Perform Simple Counting
This example performs simple counting in the connections graph.
SQL> -- Get the total number of K/V pairs of all the vertices
SQL> select /*+ parallel */ count(1)
from connectionsVT$;
299
SQL> -- Get the total number of K/V pairs of all the edges
SQL> select /*+ parallel(8) */ count(1)
from connectionsGE$;
164
SQL> -- Get the total number of vertices
SQL> select /*+ parallel */ count(distinct vid)
from connectionsVT$;
78
SQL> -- Get the total number of edges
SQL> select /*+ parallel */ count(distinct eid)
from connectionsGE$;
164
Example 5-4 Get the Set of Property Keys Used
This example gets the set of property keys used for the vertices n the connections graph.
SQL> select /*+ parallel */ distinct k
from connectionsVT$;
company
show
occupation
type
team
religion
criminal charge
music genre
genre
name
role
political party
country
13 rows selected.
SQL> -- get the set of property keys used for edges
SQL> select /*+ parallel */ distinct k
from connectionsGE$;
weight
Example 5-5 Find Vertices with a Value
This example finds vertices with a value (of any property) that is of String type, and where and the value contains two adjacent occurrences of a, e, i, o, or u, regardless of case.n the connections graph.
SQL> select vid, t, k, v
from connectionsVT$
where t=1
and regexp_like(v, '([aeiou])\1', 'i');
6 1 name Jordan Peele
6 1 show Key and Peele
54 1 name John Green
...
It is usually hard to leverage a B-Tree index for the preceding kind of query because it is difficult to know beforehand what kind of regular expression is going to be used. For the above query, you might get the following execution plan. Note that full table scan is chosen by the optimizer.
------------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop | TQ |IN-OUT| PQ Distrib |
------------------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 15 | 795 | 28 (0)| 00:00:01 | | | | | |
| 1 | PX COORDINATOR | | | | | | | | | | |
| 2 | PX SEND QC (RANDOM)| :TQ10000 | 15 | 795 | 28 (0)| 00:00:01 | | | Q1,00 | P->S | QC (RAND) |
| 3 | PX BLOCK ITERATOR | | 15 | 795 | 28 (0)| 00:00:01 | 1 | 8 | Q1,00 | PCWC | |
|* 4 | TABLE ACCESS FULL| CONNECTIONSVT$ | 15 | 795 | 28 (0)| 00:00:01 | 1 | 8 | Q1,00 | PCWP | |
------------------------------------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
4 - filter(INTERNAL_FUNCTION("V") AND REGEXP_LIKE ("V",U'([aeiou])\005C1','i') AND "T"=1 AND INTERNAL_FUNCTION("K"))
Note
-----
- Degree of Parallelism is 2 because of table property
If the Oracle Database In-Memory option is available and memory is sufficient, it can help performance to place the table (full table or a set of relevant columns) in memory. One way to achieve that is as follows:
SQL> alter table connectionsVT$ inmemory;
Table altered.
Now, entering the same SQL containing the regular expression shows a plan that performs a "TABLE ACCESS INMEMORY FULL".
--------------------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU) | Time | Pstart| Pstop | TQ |IN-OUT| PQ Distrib |
---------------------------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 15 | 795 | 28 (0)| 00:00:01 | | | | | |
| 1 | PX COORDINATOR | | | | | | | | | | |
| 2 | PX SEND QC (RANDOM) | :TQ10000 | 15 | 795 | 28 (0)| 00:00:01 | | | Q1,00 | P->S | QC (RAND) |
| 3 | PX BLOCK ITERATOR | | 15 | 795 | 28 (0)| 00:00:01 | 1 | 8 | Q1,00 | PCWC | |
|* 4 | TABLE ACCESS INMEMORY FULL| CONNECTIONSVT$ | 15 | 795 | 28 (0)| 00:00:01 | 1 | 8 | Q1,00 | PCWP | |
---------------------------------------------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
4 - filter(INTERNAL_FUNCTION("V") AND REGEXP_LIKE ("V",U'([aeiou])\005C1','i') AND "T"=1 AND INTERNAL_FUNCTION("K"))
Note
-----
- Degree of Parallelism is 2 because of table property
Parent topic: SQL-Based Property Graph Query and Analytics