Vincent Rischmann created CASSANDRA-20012:
---------------------------------------------
Summary: SAI (maybe) could support the blob CQL type
Key: CASSANDRA-20012
URL: https://issues.apache.org/jira/browse/CASSANDRA-20012
Project: Cassandra
Issue Type: Improvement
Components: Feature/SAI
Reporter: Vincent Rischmann
Hello,
we're currently exploring SAI for a use case, we have a table like this:
```
CREATE TABLE ucp.profile (
project_key blob,
profile_id blob,
age int,
PRIMARY KEY ((project_key, profile_id))
)
```
we tried using a SAI index but we get an error:
```
cqlsh:ucp> create custom index ucp_profile_project_key on ucp.profile
(project_key) using 'sai';
InvalidRequest: Error from server: code=2200 [Invalid query]
message="Unsupported type: blob"
```
The documentation is clear, it lists all the types that are supported, but it
didn't say _why_ the `blob` type is not supported and it seemed a little weird
to me that `blob` isn't supported because in my mind it should be the easiest
type to support; I have no clue if that is _true_ but I started to investigate
anyway.
I took a look at the code and stumbled upon [this
line](https://github.com/apache/cassandra/blob/6bbe85ef51d2a5a52b9a585e7c1d3031a7fb0c80/src/java/org/apache/cassandra/index/sai/StorageAttachedIndex.java#L163-L168)
which lists all the supported types. I thought "why not just add the BLOB type
and see what happens ?"
So that's basically what I did and to my surprise it _seems_ to work from my
limited testing:
```
cqlsh:ucp> CREATE TABLE ucp.profile ( project_key blob, profile_id blob,
age int, PRIMARY KEY ((project_key, profile_id)));
cqlsh:ucp> create custom index ucp_profile_profile_id on ucp.profile
(profile_id) using 'sai';
cqlsh:ucp> insert into profile(project_key, profile_id, age) values(0xcafe,
0xdeadbeef, 200);
cqlsh:ucp> select * from profile_id
= 0xdeadbeef;
cqlsh:ucp> select * from profile where profile_id = 0xdeadbeef;
project_key | profile_id | age
-------------+------------+-----
0xcafe | 0xdeadbeef | 200
(1 rows)
```
I didn't test further, but I'm left wondering if it is simply an oversight that
blob are not supported with SAI today ? and if it is _not_ an oversight, I'd
love to know the reasons.
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