Dynamic dispatch infrastructure for class member functions

[kitaisreal]

Changelog category (leave one):

• Performance Improvement

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

Improve performance of avg, sum aggregate functions if used without GROUP BY expression.

[kitaisreal]

Query

SELECT avg(key) FROM ( SELECT materialize(toNullable(1)) AS key FROM numbers(100000000) )";

Before

localhost:9000, queries 59, QPS: 15.123, RPS: 1512722049.488, MiB/s: 11541.153, result RPS: 15.123, result MiB/s: 0.000.

After

localhost:9000, queries 23, QPS: 22.770, RPS: 2277610947.922, MiB/s: 17376.793, result RPS: 22.770, result MiB/s: 0.000.