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Diffstat (limited to 'vendor/github.com/lib/pq/doc.go')
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1 files changed, 245 insertions, 0 deletions
diff --git a/vendor/github.com/lib/pq/doc.go b/vendor/github.com/lib/pq/doc.go new file mode 100644 index 0000000..a1b0297 --- /dev/null +++ b/vendor/github.com/lib/pq/doc.go @@ -0,0 +1,245 @@ +/* +Package pq is a pure Go Postgres driver for the database/sql package. + +In most cases clients will use the database/sql package instead of +using this package directly. For example: + + import ( + "database/sql" + + _ "github.com/lib/pq" + ) + + func main() { + connStr := "user=pqgotest dbname=pqgotest sslmode=verify-full" + db, err := sql.Open("postgres", connStr) + if err != nil { + log.Fatal(err) + } + + age := 21 + rows, err := db.Query("SELECT name FROM users WHERE age = $1", age) + … + } + +You can also connect to a database using a URL. For example: + + connStr := "postgres://pqgotest:password@localhost/pqgotest?sslmode=verify-full" + db, err := sql.Open("postgres", connStr) + + +Connection String Parameters + + +Similarly to libpq, when establishing a connection using pq you are expected to +supply a connection string containing zero or more parameters. +A subset of the connection parameters supported by libpq are also supported by pq. +Additionally, pq also lets you specify run-time parameters (such as search_path or work_mem) +directly in the connection string. This is different from libpq, which does not allow +run-time parameters in the connection string, instead requiring you to supply +them in the options parameter. + +For compatibility with libpq, the following special connection parameters are +supported: + + * dbname - The name of the database to connect to + * user - The user to sign in as + * password - The user's password + * host - The host to connect to. Values that start with / are for unix + domain sockets. (default is localhost) + * port - The port to bind to. (default is 5432) + * sslmode - Whether or not to use SSL (default is require, this is not + the default for libpq) + * fallback_application_name - An application_name to fall back to if one isn't provided. + * connect_timeout - Maximum wait for connection, in seconds. Zero or + not specified means wait indefinitely. + * sslcert - Cert file location. The file must contain PEM encoded data. + * sslkey - Key file location. The file must contain PEM encoded data. + * sslrootcert - The location of the root certificate file. The file + must contain PEM encoded data. + +Valid values for sslmode are: + + * disable - No SSL + * require - Always SSL (skip verification) + * verify-ca - Always SSL (verify that the certificate presented by the + server was signed by a trusted CA) + * verify-full - Always SSL (verify that the certification presented by + the server was signed by a trusted CA and the server host name + matches the one in the certificate) + +See http://www.postgresql.org/docs/current/static/libpq-connect.html#LIBPQ-CONNSTRING +for more information about connection string parameters. + +Use single quotes for values that contain whitespace: + + "user=pqgotest password='with spaces'" + +A backslash will escape the next character in values: + + "user=space\ man password='it\'s valid'" + +Note that the connection parameter client_encoding (which sets the +text encoding for the connection) may be set but must be "UTF8", +matching with the same rules as Postgres. It is an error to provide +any other value. + +In addition to the parameters listed above, any run-time parameter that can be +set at backend start time can be set in the connection string. For more +information, see +http://www.postgresql.org/docs/current/static/runtime-config.html. + +Most environment variables as specified at http://www.postgresql.org/docs/current/static/libpq-envars.html +supported by libpq are also supported by pq. If any of the environment +variables not supported by pq are set, pq will panic during connection +establishment. Environment variables have a lower precedence than explicitly +provided connection parameters. + +The pgpass mechanism as described in http://www.postgresql.org/docs/current/static/libpq-pgpass.html +is supported, but on Windows PGPASSFILE must be specified explicitly. + + +Queries + + +database/sql does not dictate any specific format for parameter +markers in query strings, and pq uses the Postgres-native ordinal markers, +as shown above. The same marker can be reused for the same parameter: + + rows, err := db.Query(`SELECT name FROM users WHERE favorite_fruit = $1 + OR age BETWEEN $2 AND $2 + 3`, "orange", 64) + +pq does not support the LastInsertId() method of the Result type in database/sql. +To return the identifier of an INSERT (or UPDATE or DELETE), use the Postgres +RETURNING clause with a standard Query or QueryRow call: + + var userid int + err := db.QueryRow(`INSERT INTO users(name, favorite_fruit, age) + VALUES('beatrice', 'starfruit', 93) RETURNING id`).Scan(&userid) + +For more details on RETURNING, see the Postgres documentation: + + http://www.postgresql.org/docs/current/static/sql-insert.html + http://www.postgresql.org/docs/current/static/sql-update.html + http://www.postgresql.org/docs/current/static/sql-delete.html + +For additional instructions on querying see the documentation for the database/sql package. + + +Data Types + + +Parameters pass through driver.DefaultParameterConverter before they are handled +by this package. When the binary_parameters connection option is enabled, +[]byte values are sent directly to the backend as data in binary format. + +This package returns the following types for values from the PostgreSQL backend: + + - integer types smallint, integer, and bigint are returned as int64 + - floating-point types real and double precision are returned as float64 + - character types char, varchar, and text are returned as string + - temporal types date, time, timetz, timestamp, and timestamptz are + returned as time.Time + - the boolean type is returned as bool + - the bytea type is returned as []byte + +All other types are returned directly from the backend as []byte values in text format. + + +Errors + + +pq may return errors of type *pq.Error which can be interrogated for error details: + + if err, ok := err.(*pq.Error); ok { + fmt.Println("pq error:", err.Code.Name()) + } + +See the pq.Error type for details. + + +Bulk imports + +You can perform bulk imports by preparing a statement returned by pq.CopyIn (or +pq.CopyInSchema) in an explicit transaction (sql.Tx). The returned statement +handle can then be repeatedly "executed" to copy data into the target table. +After all data has been processed you should call Exec() once with no arguments +to flush all buffered data. Any call to Exec() might return an error which +should be handled appropriately, but because of the internal buffering an error +returned by Exec() might not be related to the data passed in the call that +failed. + +CopyIn uses COPY FROM internally. It is not possible to COPY outside of an +explicit transaction in pq. + +Usage example: + + txn, err := db.Begin() + if err != nil { + log.Fatal(err) + } + + stmt, err := txn.Prepare(pq.CopyIn("users", "name", "age")) + if err != nil { + log.Fatal(err) + } + + for _, user := range users { + _, err = stmt.Exec(user.Name, int64(user.Age)) + if err != nil { + log.Fatal(err) + } + } + + _, err = stmt.Exec() + if err != nil { + log.Fatal(err) + } + + err = stmt.Close() + if err != nil { + log.Fatal(err) + } + + err = txn.Commit() + if err != nil { + log.Fatal(err) + } + + +Notifications + + +PostgreSQL supports a simple publish/subscribe model over database +connections. See http://www.postgresql.org/docs/current/static/sql-notify.html +for more information about the general mechanism. + +To start listening for notifications, you first have to open a new connection +to the database by calling NewListener. This connection can not be used for +anything other than LISTEN / NOTIFY. Calling Listen will open a "notification +channel"; once a notification channel is open, a notification generated on that +channel will effect a send on the Listener.Notify channel. A notification +channel will remain open until Unlisten is called, though connection loss might +result in some notifications being lost. To solve this problem, Listener sends +a nil pointer over the Notify channel any time the connection is re-established +following a connection loss. The application can get information about the +state of the underlying connection by setting an event callback in the call to +NewListener. + +A single Listener can safely be used from concurrent goroutines, which means +that there is often no need to create more than one Listener in your +application. However, a Listener is always connected to a single database, so +you will need to create a new Listener instance for every database you want to +receive notifications in. + +The channel name in both Listen and Unlisten is case sensitive, and can contain +any characters legal in an identifier (see +http://www.postgresql.org/docs/current/static/sql-syntax-lexical.html#SQL-SYNTAX-IDENTIFIERS +for more information). Note that the channel name will be truncated to 63 +bytes by the PostgreSQL server. + +You can find a complete, working example of Listener usage at +http://godoc.org/github.com/lib/pq/example/listen. + +*/ +package pq |