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mysql_param

Purpose​

mysql_param extracts one parameter of a recorded MySQL prepared statement execution. Pair it with a transform such as rand_string to send a new value on every replay, for example a unique email that would otherwise fail with 1062 Duplicate entry the second time it is inserted.

It applies only to requests, and only to recorded statement executions. Other RRPairs are left alone.

Usage​

"type": "mysql_param",
"config": {
    "index": "3"
}
  • index - the position of the ? placeholder in the statement, counting from 1.
  • name - (optional, instead of index) the name of a parameter set with MySQL query attributes.

The extracted value is text: numbers in decimal, dates as MySQL literals such as 2026-04-30 09:15:00, and NULL as an empty value. When a transform writes a new value, it keeps the recorded type if the value fits, so an integer column still gets an integer. Anything else is sent as a string, which MySQL converts or rejects as it would a literal in the statement.

Example​

Regenerate the email, the third placeholder, of every replayed user insert:

{
    "filters": {"filters": [{"include": true, "detectedLocation": "INSERT INTO users", "operator": "CONTAINS"}]},
    "extractor": {"type": "mysql_param", "config": {"index": "3"}},
    "transforms": [{"type": "rand_string", "config": {"pattern": "[a-z0-9]{12}@load\\.test"}}]
}

See MySQL Load and Regression Testing for the full walkthrough.