Is this a bug?

[zzl221000]

I have a big table with 500 million data. Update the database with the following statement

A: merge (n:rlnode ? ) merge (m:rlnode ?) merge (n)-[:knows ?]->(m); B:
merge (n:rlnode %s ) merge (m:rlnode %s) merge (n)-[:knows %s]->(m); A statement is executed after setting PGobject, it takes 5 minutes. B statement is executed after splicing the string, in 5 milliseconds