Postgrex v0.11.1 Postgrex
PostgreSQL driver for Elixir.
This module handles the connection to Postgres, providing support for queries, transactions, connection backoff, logging, pooling and more.
Note that the notifications API (pub/sub) supported by Postgres is
handled by Postgrex.Notifications
. Hence, to use this feature,
you need to start a separate (notifications) connection.
Summary
Functions
Returns a supervisor child specification for a DBConnection pool
Closes an (extended) prepared query and returns :ok
or
{:error, %Postgrex.Error{}}
if there was an error. Closing a query releases
any resources held by postgresql for a prepared query with that name. See
Postgrex.Query
for the query data
Closes an (extended) prepared query and returns :ok
or raises
Postgrex.Error
if there was an error. See close/3
Runs an (extended) prepared query and returns the result as
{:ok, %Postgrex.Result{}}
or {:error, %Postgrex.Error{}}
if there was an
error. Parameters are given as part of the prepared query, %Postgrex.Query{}
.
See the README for information on how Postgrex encodes and decodes Elixir
values by default. See Postgrex.Query
for the query data and
Postgrex.Result
for the result data
Runs an (extended) prepared query and returns the result or raises
Postgrex.Error
if there was an error. See execute/4
Returns a cached map of connection parameters
Prepares an (extended) query and returns the result as
{:ok, %Postgrex.Query{}}
or {:error, %Postgrex.Error{}}
if there was an
error. Parameters can be set in the query as $1
embedded in the query
string. To execute the query call execute/4
. To close the prepared query
call close/3
. See Postgrex.Query
for the query data
Prepares an (extended) query and returns the prepared query or raises
Postgrex.Error
if there was an error. See prepare/4
Runs an (extended) query and returns the result as {:ok, %Postgrex.Result{}}
or {:error, %Postgrex.Error{}}
if there was an error. Parameters can be
set in the query as $1
embedded in the query string. Parameters are given as
a list of elixir values. See the README for information on how Postgrex
encodes and decodes Elixir values by default. See Postgrex.Result
for the
result data
Runs an (extended) query and returns the result or raises Postgrex.Error
if
there was an error. See query/3
Rollback a transaction, does not return
Start the connection process and connect to postgres
Acquire a lock on a connection and run a series of requests inside a
transaction. The result of the transaction fun is return inside an :ok
tuple: {:ok, result}
Types
conn :: DBConnection.conn
A connection process name, pid or reference.
A connection reference is used when making multiple requests to the same
connection, see transaction/3
and :after_connect
in start_link/1
.
Functions
Specs
child_spec(Keyword.t) :: Supervisor.Spec.spec
Returns a supervisor child specification for a DBConnection pool.
Specs
close(conn, Postgrex.Query.t, Keyword.t) ::
:ok |
{:error, Postgrex.Error.t}
Closes an (extended) prepared query and returns :ok
or
{:error, %Postgrex.Error{}}
if there was an error. Closing a query releases
any resources held by postgresql for a prepared query with that name. See
Postgrex.Query
for the query data.
Options
:pool_timeout
- Time to wait in the queue for the connection (default:5000
):queue
- Whether to wait for connection in a queue (default:true
);:timeout
- Close request timeout (default:5000
);:pool
- The pool module to use, must match that set onstart_link/1
, seeDBConnection
Examples
query = Postgrex.prepare!(conn, "CREATE TABLE posts (id serial, title text)")
Postgrex.close(conn, query)
Specs
close!(conn, Postgrex.Query.t, Keyword.t) :: :ok
Closes an (extended) prepared query and returns :ok
or raises
Postgrex.Error
if there was an error. See close/3
.
Specs
execute(conn, Postgrex.Query.t, list, Keyword.t) ::
{:ok, Postgrex.Result.t} |
{:error, Postgrex.Error.t}
Runs an (extended) prepared query and returns the result as
{:ok, %Postgrex.Result{}}
or {:error, %Postgrex.Error{}}
if there was an
error. Parameters are given as part of the prepared query, %Postgrex.Query{}
.
See the README for information on how Postgrex encodes and decodes Elixir
values by default. See Postgrex.Query
for the query data and
Postgrex.Result
for the result data.
Options
:pool_timeout
- Time to wait in the queue for the connection (default:5000
):queue
- Whether to wait for connection in a queue (default:true
);:timeout
- Execute request timeout (default:5000
);:decode_mapper
- Fun to map each row in the result to a term after decoding, (default:fn x -> x end
);:pool
- The pool module to use, must match that set onstart_link/1
, seeDBConnection
Examples
query = Postgrex.prepare!(conn, "CREATE TABLE posts (id serial, title text)")
Postgrex.execute(conn, query, [])
query = Postgrex.prepare!(conn, "SELECT id FROM posts WHERE title like $1")
Postgrex.execute(conn, query, ["%my%"])
Specs
execute!(conn, Postgrex.Query.t, list, Keyword.t) :: Postgrex.Result.t
Runs an (extended) prepared query and returns the result or raises
Postgrex.Error
if there was an error. See execute/4
.
Returns a cached map of connection parameters.
Options
:pool_timeout
- Call timeout (default:5000
):pool
- The pool module to use, must match that set onstart_link/1
, seeDBConnection
Specs
prepare(conn, iodata, iodata, Keyword.t) ::
{:ok, Postgrex.Query.t} |
{:error, Postgrex.Error.t}
Prepares an (extended) query and returns the result as
{:ok, %Postgrex.Query{}}
or {:error, %Postgrex.Error{}}
if there was an
error. Parameters can be set in the query as $1
embedded in the query
string. To execute the query call execute/4
. To close the prepared query
call close/3
. See Postgrex.Query
for the query data.
Options
:pool_timeout
- Time to wait in the queue for the connection (default:5000
):queue
- Whether to wait for connection in a queue (default:true
);:timeout
- Prepare request timeout (default:5000
);:pool
- The pool module to use, must match that set onstart_link/1
, seeDBConnection
:null
- The atom to use as a stand in for postgres’NULL
in encoding and decoding;
Examples
Postgrex.prepare(conn, "CREATE TABLE posts (id serial, title text)")
Specs
prepare!(conn, iodata, iodata, Keyword.t) :: Postgrex.Query.t
Prepares an (extended) query and returns the prepared query or raises
Postgrex.Error
if there was an error. See prepare/4
.
Specs
query(conn, iodata, list, Keyword.t) ::
{:ok, Postgrex.Result.t} |
{:error, Postgrex.Error.t}
Runs an (extended) query and returns the result as {:ok, %Postgrex.Result{}}
or {:error, %Postgrex.Error{}}
if there was an error. Parameters can be
set in the query as $1
embedded in the query string. Parameters are given as
a list of elixir values. See the README for information on how Postgrex
encodes and decodes Elixir values by default. See Postgrex.Result
for the
result data.
Options
:pool_timeout
- Time to wait in the queue for the connection (default:5000
):queue
- Whether to wait for connection in a queue (default:true
);:timeout
- Query request timeout (default:5000
);:decode_mapper
- Fun to map each row in the result to a term after decoding, (default:fn x -> x end
);:pool
- The pool module to use, must match that set onstart_link/1
, seeDBConnection
:null
- The atom to use as a stand in for postgres’NULL
in encoding and decoding;
Examples
Postgrex.query(conn, "CREATE TABLE posts (id serial, title text)", [])
Postgrex.query(conn, "INSERT INTO posts (title) VALUES ('my title')", [])
Postgrex.query(conn, "SELECT title FROM posts", [])
Postgrex.query(conn, "SELECT id FROM posts WHERE title like $1", ["%my%"])
Specs
query!(conn, iodata, list, Keyword.t) :: Postgrex.Result.t
Runs an (extended) query and returns the result or raises Postgrex.Error
if
there was an error. See query/3
.
Specs
rollback(DBConnection.t, any) :: no_return
Rollback a transaction, does not return.
Aborts the current transaction fun. If inside multiple transaction/3
functions, bubbles up to the top level.
Example
{:error, :oops} = Postgrex.transaction(pid, fn(conn) ->
DBConnection.rollback(conn, :bar)
IO.puts "never reaches here!"
end)
Specs
start_link(Keyword.t) ::
{:ok, pid} |
{:error, Postgrex.Error.t | term}
Start the connection process and connect to postgres.
Options
:hostname
- Server hostname (default: PGHOST env variable, then localhost);:port
- Server port (default: 5432);:database
- Database (required);:username
- Username (default: PGUSER env variable, then USER env var);:password
- User password (default PGPASSWORD);:parameters
- Keyword list of connection parameters;:timeout
- Connect timeout in milliseconds (default:5000
);:ssl
- Set totrue
if ssl should be used (default:false
);:ssl_opts
- A list of ssl options, see ssl docs;:socket_options
- Options to be given to the underlying socket;:sync_connect
- Block instart_link/1
until connection is set up (default:false
):extensions
- A list of{module, opts}
pairs wheremodule
is implementing thePostgrex.Extension
behaviour andopts
are the extension options;:prepare
- How to prepare queries, either:named
to use named queries or:unnamed
to force unnamed queries (default::named
);:after_connect
- A function to run on connect, either a 1-arity fun called with a connection reference,{module, function, args}
with the connection reference prepended toargs
ornil
, (default:nil
):idle_timeout
- Idle timeout to ping postgres to maintain a connection (default:5000
):backoff_start
- The first backoff interval when reconnecting (default:200
);:backoff_max
- The maximum backoff interval when reconnecting (default:15_000
);:backoff_type
- The backoff strategy when reconnecting,:stop
for no backoff and to stop (see:backoff
, default::jitter
):transactions
- Set to:strict
to error on unexpected transaction state, otherwise set tonaive
(default::naive
);:pool
- The pool module to use, seeDBConnection
, it must be included with all requests if not the default (default:DBConnection.Connection
);:null
- The atom to use as a stand in for postgres’NULL
in encoding and decoding (default:nil
);
Specs
Acquire a lock on a connection and run a series of requests inside a
transaction. The result of the transaction fun is return inside an :ok
tuple: {:ok, result}
.
To use the locked connection call the request with the connection
reference passed as the single argument to the fun
. If the
connection disconnects all future calls using that connection
reference will fail.
rollback/2
rolls back the transaction and causes the function to
return {:error, reason}
.
transaction/3
can be nested multiple times if the connection
reference is used to start a nested transaction. The top level
transaction function is the actual transaction.
Options
:pool_timeout
- Time to wait in the queue for the connection (default:5000
):queue
- Whether to wait for connection in a queue (default:true
);:timeout
- Transaction timeout (default:5000
);:pool
- The pool module to use, must match that set onstart_link/1
, seeDBConnection; *
:mode- Set to
:savepointto use savepoints instead of an SQL transaction, otherwise set to
:transaction(default:
:transaction); The
:timeoutis for the duration of the transaction and all nested transactions and requests. This timeout overrides timeouts set by internal transactions and requests. The
:pooland
:mode` will be used for all requests inside the transaction function. ## Example {:ok, res} = Postgrex.transaction(pid, fn(conn) -> Postgrex.query!(conn, “SELECT title FROM posts”, []) end)