feature req: SQL codecs need to inject or parse trace headers from comments

Having the ability to trace database calls is very useful. Imagine the following example flow:

app---(sql query)-->sidecar--->DB

if app sends SQL queries with the trace headers as SQL comments, then the sidecar can emit client-side trace spans, recording the DB call durations. [The more industrious lot can parse DB query logs to extract trace headers and emit server side spans?]

if app doesn't send the trace headers as comments, the sidecar can still inject them (it will be a broken trace, but a trace nevertheless).

I am not sure if mongodb supports comments - the same can be done for mongo as well.