How to concurrently iterate through an sql result set in Golang?

Question

The next() method is sequential, is there a way to concurrently iterate through the loop?

I have a result set of 200k rows that I am looping through sequentially and doing logic on each row and want to split it up.

Answer 1

The sql.Rows you get back from your query can't be used concurrently (I believe).

but you can do most of the heavy lifting in goroutines.

Here is an example (non-working, but close), on Play

package main

import "fmt"
import "sql"

type Row struct {
    x string
    y string
    z string
}

func processor(ch chan Row) {
    for row := range <-ch {
        // be awesome
    }
}
func main() {
    ch := make(chan Row)
    // two handler go routines (current processors)
    go processor(ch)
    go processor(ch)
    rows := db.Query("select x,y,z from whatever")
    for rows.Next() {
        var row Row
        if err := rows.Scan(&row.x, &row.y, &row.z); err != nil {
            // do something with error
        } else {
            ch <- row
        }
    }
}