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Database wrapper that manage read write connections
Install
go get github.com/andizzle/rwdb
Create connections
package main
import"github.com/andizzle/rwdb"varconns= []string{
"tcp://user:pass@write/dbname",
"tcp://user:pass@read1/dbname",
"tcp://user:pass@read2/dbname",
"tcp://user:pass@read3/dbname",
}
// unable to open write will cause an errordb, err:=rwdb.Open("driver", conns...)
Rotation read and Sticky read
Query a database rotate the use of database connections
Basic usage
db, err:=rwdb.Open("driver", conns...)
// Use the first connectiondb.QueryContext(ctx)
// Use the next connectiondb.QueryContext(ctx)
Execute a statement will cause all subsequent queries to use the write connection (sticky connection). This is to allow the
immediate reading of records that have been written to the database during the current request cycle.
db, err:=rwdb.Open("driver", conns...)
// Use the next connectiondb.QueryContext(ctx)
// Use the write conenctiondb.ExecContext(ctx)
// Use the write connectiondb.Query()
Sticky can be turned off
db.SetSticky(false)
A more practical example
The db is marked as modified if there's a successful Write to the databse, which turns on the sticky logic.
However, the real world usecase would require modified value to be reset on each request session.
Here's what we can do:
db, err:=rwdb.Open("driver", conns...)
funcRecordUserLogin() {
d:=db.New() // This will make sure the following read are not affected by // other sessions' write actiond.Query("SELECT * from `users` where id = ?")
...d.Exec("UPDATE `users` set last_login_at = now();")
d.Query(...) // Connection is set to the writer
}