\set ECHO none
add_provenance

(1 row)
remove_provenance

(1 row)
p_row|p_ev|distinct_tokens
0.500|0.500|t
(1 row)
remove_provenance

(1 row)
id|p_row|p_ev
1|0.500|0.500
2|0.500|0.500
3|0.500|
(3 rows)
remove_provenance

(1 row)
p_row
0.500
(1 row)
remove_provenance

(1 row)
p_row|p_ev
0.500|0.250
(1 row)
remove_provenance

(1 row)
p_ev
0.500
(1 row)
ERROR:  ProvSQL: a subquery over a provenance-tracked relation cannot be used as a scalar subquery / IN / EXISTS expression; put it in the FROM clause instead
remove_provenance

(1 row)