A little more investigation shows that the additional SELECT statement originates from a call to getParameterMetaData by the Groovy Sql object.
The impact is: * Prepared statements are slower than literal SQL statements * Batch inserts are slower than row-by-row inserts Bug logged at https://issues.apache.org/jira/browse/GROOVY-9676 See attachment to this bug for test details and measurements. ________________________________ From: Mike M <mike...@outlook.com> Sent: 01 August 2020 08:29 To: users@groovy.apache.org <users@groovy.apache.org> Subject: SQL: Bind variables in INSERT statement resulting in extra SELECT statement A statement such as: String qry = "INSERT INTO Author (firstname, lastname) VALUES ('$name', '$name')" sql.execute qry results in one database roundtrip, as one would expect. Using bind variables such as this: sql.execute "INSERT INTO Author (firstname, lastname) VALUES ($fname, $lname)" results in 2 roundtrips (as visible in Wireshark): * The INSERT statement, with the bind variables * A subsequent SELECT firstname,lastname FROM Author Is Groovy generating this second statement, or is it the JDBC driver? And why? BTW: I suspect there is a where clause on the select, but I do not see it in the wireshark capture.
