pdpotter commented on issue #45:
URL: https://github.com/apache/incubator-age/issues/45#issuecomment-812524846
It would indeed be very useful to enable the creation of constraints /
indexes. This could help to accelerate the creation of edges between nodes that
were added earlier, which slows down a lot when there are a lot of nodes with
the same label:
```
SELECT * FROM cypher('graph_name', $$
MATCH (d:LabelA {id: 1}), (r:LabelB {id: 2})
CREATE (d)-[:Relation {prop: 'value'}]->(r)
$$) as (a agtype)
```
The `CREATE UNIQUE`, `CREATE CONSTRAINT`, and `CREATE INDEX` clauses /
commands [are part of cypher, but not of
openCypher](https://github.com/opencypher/openCypher/blob/master/docs/standardisation-scope.adoc#language-features-excluded-from-opencypher),
so I don't know what the best approach would be here.
@ehsanonline
You can create a unique index, which will prevent the creation of duplicate
values, but will not speed up matching, by creating an immutable function that
casts to json over text
```
CREATE OR REPLACE FUNCTION get_name(properties agtype)
RETURNS text
AS
$BODY$
select $1::text::json->>'name';
$BODY$
LANGUAGE sql
IMMUTABLE;
```
and using that immutable function in the create index command
```
CREATE UNIQUE INDEX person_name_idx ON mygraph.person(get_name(properties)) ;
```
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