postgresqlでのデータの読み込み

/* sql_insertion_test01.go * Synthetic test for simple insert operations into postgresql database * Call: ./sql_insertion_test01 * Pls, do not use name "insert_test", because this name is always used by go-pkg-system */ package main import ( _ "github.com/lib/pq" "database/sql" "fmt" "time" ) const DB_CONNECT_STRING = "host=localhost port=5432 user=your_role password=your_password dbname=your_database sslmode=disable" func main() { db, err := sql.Open("postgres", DB_CONNECT_STRING) defer db.Close() if err != nil { fmt.Printf("Database opening error -->%v\n", err) panic("Database error") } init_database(&db) make_insertion(&db) } /*-----------------------------------------------------------------------------*/ func init_database(pdb **sql.DB) { db := *pdb init_db_strings := []string{ "DROP SCHEMA IF EXISTS sb CASCADE;", "CREATE SCHEMA sb;", //be careful - next multiline string is quoted by backquote symbol `CREATE TABLE sb.test_data( id serial, device_id integer not null, parameter_id integer not null, value varchar(100), event_ctime timestamp default current_timestamp, constraint id_pk primary key (id));`} for _, qstr := range init_db_strings { _, err := db.Exec(qstr) if err != nil { fmt.Printf("Database init error -->%v\n", err) panic("Query error") } } fmt.Println("Database rebuilded successfully") } /*-----------------------------------------------------------------------------*/ func make_insertion(pdb **sql.DB) { db := *pdb const TEST_NUMBER = 400000 // backquotes for next multiline string const INSERT_QUERY = `insert into sb.test_data(device_id, parameter_id, value) values ($1, $2, $3);` insert_query, err := db.Prepare(INSERT_QUERY) defer insert_query.Close() if err != nil { fmt.Printf("Query preparation error -->%v\n", err) panic("Test query error") } t1 := time.Now() for i := 0; i < TEST_NUMBER; i++ { _, err = insert_query.Exec(i, i, "0") if err != nil { fmt.Printf("Query execution error -->%v\n", err) panic("Error") } } t2 := time.Since(t1) fmt.Printf("%v queries are executed for %v seconds (%v per second)\n", TEST_NUMBER, t2.Seconds(), TEST_NUMBER/t2.Seconds()) // do not forget clean up after work ) //_, err = db.Query("TRUNCATE sb.test_data;") }