Halephant

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pgx ​

pgx is the most widely used PostgreSQL driver for Go.

Read-only transactions ​

Use pgx.TxOptions with AccessMode: pgx.ReadOnly:

main.go
go
tx, err := conn.BeginTx(ctx, pgx.TxOptions{AccessMode: pgx.ReadOnly})
// Sends: begin read only

With database/sql:

main.go
go
tx, err := db.BeginTx(ctx, &sql.TxOptions{ReadOnly: true})

Halephant detects begin read only and routes the transaction to a replica.

Separate pools ​

If you separate read and write traffic at the pool level:

main.go
go
writePool, _ := pgxpool.New(ctx, "postgres://myapp:pw@halephant:6432/myapp")
readPool, _ := pgxpool.New(ctx, "postgres://myapp_ro:pw@halephant:6432/myapp")

See the read replica guide for halephant configuration.