git.net

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: scrolling in ElasticSearch adapter


Hey,

not sure if this should be an SQL keyword. JDBC specifies various constants that can be used at statement creation time: https://docs.oracle.com/javase/7/docs/api/java/sql/ResultSet.html

Not sure though if or how these configurations are accessible for data stores or dialects, but IMO using these would be the proper way.

Regards

Christian

Am 24.10.2018 um 18:44 schrieb Andrei Sereda:
Hello,


I was thinking about adding [scrolling functionality](
https://www.elastic.co/guide/en/elasticsearch/reference/current/search-request-scroll.html)
to elastic search adapter. Since scrolling has non-negligible effect on the
cluster it should be selectively enabled on per query basis. So, likely,
user has to explicitly set "scroll flag" somewhere.

Most natural way seems in SQL. [Calcite sql grammar](
https://calcite.apache.org/docs/reference.html) has `SCROLL` keyword
(unused to my knowledge). There were also discussions about adding hints to
Calcite.

### Examples
```sql
-- special sql keyword ?
SCROLL select * from elastic;

-- assuming hints are available in calcite
/* HINT: scroll */ select * from elastic;
```

What people think about this use-case ? Are there better ideas ?

Regards,
Andrei.