This is a wrapper for the `sql.Driver` in `github.com/lib/pq` which allows you to set the schema search path for each connection in the connection pool.

pq_with_schema_selector.go

package postgres

import (
	"database/sql"
	"database/sql/driver"
	"fmt"
	"github.com/lib/pq"
	"strings"
)

type drv struct{}

func init() {
	sql.Register("pq-schema", &drv{})
}

func (drv *drv) Open(data_source string) (driver.Conn, error) {
	conn, err := pq.Open(data_source)
	if err != nil {
		return nil, err
	}

	data_source, schemas, err := parseOpts(data_source)

	if err != nil {
		conn.Close()
		return nil, err
	}

	if schemas == "" {
		return conn, nil
	}

	execer, ok := conn.(driver.Execer)
	if !ok {
		conn.Close()
		return nil, fmt.Errorf("Expected driver to be an driver.Execer")
	}

	_, err = execer.Exec("SET search_path TO "+schemas+";", nil)
	if err != nil {
		return nil, err
	}

	return conn, nil
}

func parseOpts(in string) (out, schemas string, err error) {
	if len(in) == 0 {
		return
	}

	ops := []string{}

	ps := strings.Split(in, " ")
	for _, p := range ps {
		kv := strings.Split(p, "=")
		if len(kv) < 2 {
			return "", "", fmt.Errorf("invalid option: %q", p)
		}
		if kv[0] == "search_path" {
			schemas = kv[1]
		} else {
			ops = append(ops, p)
		}
	}
	out = strings.Join(ops, " ")

	schemas = strings.Replace(schemas, ";", "", -1)

	return
}