impl pg-lo-dmeo

cmd/pg-lo-demo/main.go

@@ -1,9 +1,11 @@
 package main
 
 import (
+	"bytes"
 	"context"
 	"database/sql"
 	"flag"
+	"fmt"
 	"os"
 
 	"pg/src/with"
@@ -25,8 +27,60 @@ func run(ctx context.Context) error {
 	}
 
 	return with.PSQL(ctx, *c, func(pg *sql.DB) error {
-		// SELECT lo_creat(-1);
+		cleanup := func() error {
-		// SELECT pg_catalog.lowrite(0, '\\037\\213\\010\\000\\000\\000\\000\\000\\000\\000\\245\\220;n\\3030\\014')
+			rows, err := pg.QueryContext(ctx, `SELECT oid FROM oids`)
-		return ctx.Err()
+			if err != nil {
+				return nil
+			}
+			defer rows.Close()
+			for rows.Next() {
+				var oid any
+				if err := rows.Scan(&oid); err != nil {
+					return err
+				}
+				pg.ExecContext(ctx, `SELECT lo_unlink($1)`, oid)
+			}
+			return rows.Err()
+		}
+		defer cleanup()
+
+		if err := cleanup(); err != nil {
+			return fmt.Errorf("failed initial cleanup: %w", err)
+		}
+
+		if _, err := pg.ExecContext(ctx, `
+			DROP TABLE IF EXISTS oids;
+			CREATE TABLE IF NOT EXISTS oids (id INTEGER PRIMARY KEY, oid OID);
+		`); err != nil {
+			return fmt.Errorf("failed initial table setup: %w", err)
+		}
+
+		if _, err := pg.ExecContext(ctx, `
+			INSERT INTO oids (
+				id,
+				oid
+			)
+			VALUES (
+				1,
+				lo_from_bytea(
+					0,
+					$1
+				)
+			) ON CONFLICT DO NOTHING
+		`, []byte("hello world")); err != nil {
+			return fmt.Errorf("failed lo_from_bytea: %w", err)
+		}
+
+		var got []byte
+		row := pg.QueryRowContext(ctx, `SELECT lo_get((SELECT oid FROM oids WHERE id=1))`)
+		if err := row.Err(); err != nil {
+			return err
+		} else if err := row.Scan(&got); err != nil {
+			return err
+		} else if !bytes.Equal(got, []byte("hello world")) {
+			return fmt.Errorf("weird lo_get: %q", got)
+		}
+
+		return cleanup()
 	})
 }