Reply To: Compression for null string column

[rocuinneagain]

I expect this entry in 4.0 README for 2022.04.15 is the version from where you will see the improvement:

2022.04.15
NEW
anymap write now detects consecutive deduplicated (address matching) toplevel objects, skipping them to save space
 q)a:("hi";"there";"world");`:a0 set a;`:a1 set a@where 1000 2000 3000;(hcount`$":a0#")=hcount`$":a1#"
improved memory efficiency of writing nested data sourced from a type 77 file, commonly encountered during compression of files. e.g.
 q)`:a set 500000 100#"abc";system"ts `:b set get`:a" / was 76584400 bytes, now 8390720