Trying to get the last 20 edges from a vertex

[André Marques]

Hi,

When I execute this query: select from (select expand(outE('InCompliment')) from #27:3590) order by @rid desc limit 20

It always evaluates all the 'InCompliment' edges before return the last 20 records.

When the vertex have a lot of edges, the query slows down a lot.

I also tried select from InCompliment where out = #27:3590 order by @rid desc limit 20 using a notunique_hash_index on InCompliment(out), but it also didn't work.

Anyone knows how to do a faster 'order by desc'?

Using OrientDB Community 2.0.12.

 

[SavioL]

Hi,
maybe this link may help you:

ORDER BY performance - best practice

regards,
Savio L.

[André Marques]

Hi,

Thanks for your reply, but I've already tried that.

Is the a way to iterate over only the last edges from a vertex?

Any other suggestions?

[Luca Garulli]

Hi,

Take a look at: http://orientdb.com/docs/last/Graph-Database-Tinkerpop.html#ordered-edges. Once they are ordered hey could be managed as a list.

Best Regards,

Founder & CEO

OrientDB

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[André Marques]

Hi Luca,

Thanks, ordered edges does the job.

Is it possible to create an ordered list property using only SQL?

[Luca Garulli]

Hi,

Right now you can do that only by setting it in the schema. However, this could be an enhancement. Would you like to open a new issue for that?

Best Regards,

Founder & CEO

OrientDB

[André Marques]

Hi,

Created: https://github.com/orientechnologies/orientdb/issues/4541

[Luca Garulli]

Resolved by executing these SQL commands:

create property out_Photos LINKLIST
alter property User.out_Photos custom ordered=true

Best Regards,

Founder & CEO

OrientDB