sql: columnar direct scan results in 10x more messages

[cucaroach]

Setup:

 create table t(i int, s string);      
 insert into t select generate_series(1,100000), repeat("asdfasdf", 1024);

with columnar direct scan:

  maximum memory usage: 144 KiB
  network usage: 7.2 MiB (7,261 messages)
  sql cpu time: 4ms

w/o

  maximum memory usage: 10 MiB
  network usage: 6.4 MiB (805 messages)
  sql cpu time: 95ms

Jira issue: CRDB-26103

[mgartner]

@yuzefovich are you planning on working on this for v23.2?

[yuzefovich]

No, I don't think so.