Shlomi Livne, VP of R&D at ScyllaDB, presented on the performance benefits of using user-defined types (UDTs) in ScyllaDB. He explained that with traditional columns, each column has overhead and flexibility comes at a price. However, with frozen UDTs, the columns are treated as a single unit, sharing metadata and improving performance. Livne showed results of a test where UDTs with many fields outperformed traditional columns with the same number of fields. However, he noted that Scylla's row cache and Java driver performance need improvement for UDTs.

1. PRESENTATION TITLE ON ONE LINE
AND ON TWO LINES
First and last name
Position, company
If You Care About Performance
Use User Defined Types
VP of R&D, ScyllaDB
Shlomi Livne

2. PRESENTATION TITLE ON ONE LINE
AND ON TWO LINES
First and last name
Position, company
Shlomi Livne
2
Shlomi is VP of R&D at ScyllaDB. Prior to ScyllaDB,
he led the research and development team at
Convergin, which was acquired by Oracle.

3. PRESENTATION TITLE ON ONE LINE
AND ON TWO LINES
First and last name
Position, company
Every column has an overhead
For each Column/Cell in a Row you can
▪ Insert/Update independently
▪ Set a different TTL
o CQL: INSERT INTO … USING TTL X;
▪ Set a different Writetime
o CQL: INSERT INTO … USING WRITETIME X;
▪ Delete independently
This “flexibility” comes with a price - do you really need it ?
3

4. PRESENTATION TITLE ON ONE LINE
AND ON TWO LINES
First and last name
Position, company
Frozen User Defined Types
▪ User Defined Types - allows the user to define a structure
▪ In Scylla frozen<UDT> are supported
▪ frozen<UDT> are treated as a single column
o they share all the metadata
o an insert/update will set the complete cell (till we implement
https://github.com/scylladb/scylla/issues/2201)
o select can extract a subset of a UDT value
4

5. PRESENTATION TITLE ON ONE LINE
AND ON TWO LINES
First and last name
Position, company
So how much “better” are UDTs ?
Example:
▪ Compares
o Tables of 10,20,30,40,50 blob columns
o Tables with a frozen udt with 10,20,30,40,50 blob fields
▪ Write workload: all columns/fields are populated with 10 bytes
▪ Read workload: all columns/fields are retrieved
5

6. PRESENTATION TITLE ON ONE LINE
AND ON TWO LINES
First and last name
Position, company
6

7. PRESENTATION TITLE ON ONE LINE
AND ON TWO LINES
First and last name
Position, company
7

8. PRESENTATION TITLE ON ONE LINE
AND ON TWO LINES
First and last name
Position, company
8

9. PRESENTATION TITLE ON ONE LINE
AND ON TWO LINES
First and last name
Position, company
9

10. PRESENTATION TITLE ON ONE LINE
AND ON TWO LINES
First and last name
Position, company
2 last comments:
▪ Scylla’s row cache - caches complete rows
o It will cache all the row columns - so retrieving a partial set of columns still
forces scylla to read from disk the complete row
▪ There’s an additional “overhead” on the client side, a sample
showed that the Java driver is not as performant in UDTs (test it
out)
10

11. PRESENTATION TITLE ON ONE LINE
AND ON TWO LINES
First and last name
Position, company
THANK YOU
shlomi@scylladb.com
@ShlomiLivne
Any questions?