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Postgres module

transaction

procedure · 4 overloadssince 0.27.0Source

Runs body in a transaction on a connection from the pool. The transaction commits when body returns no error, and rolls back when it returns one (which comes out of transaction) or a statement in it failed. A serialization failure or deadlock (40001, 40P01) runs body again, up to retries more times, so body must be safe to repeat. data is passed through, as Jai procedures capture nothing.

Example
Transfer :: struct { from: s64; to: s64; amount: s64; }
error := Pg.transaction(pool, Transfer.{ 1, 2, 10 }, (tx: *Pg.Connection, t: Transfer) -> Pg.Pg_Error {
    _, error := Pg.query_dynamic(tx, "update accounts set balance = balance - $1 where id = $2", t.amount, t.from);
    if error.kind != .NONE return error;
    _, error = Pg.query_dynamic(tx, "update accounts set balance = balance + $1 where id = $2", t.amount, t.to);
    return error;
}, .SERIALIZABLE, retries = 3);

Not run: the example is marked ignore.

Not run: it needs a PostgreSQL server.

transaction :: (
    pool: *Pool,
    data: $T,
    body: (tx: *Connection, data: T) -> Pg_Error,
    isolation := Isolation.DEFAULT,
    retries := 0,
    read_only := false
) -> Pg_Error

Runs body in a transaction on a connection from the pool. The transaction commits when body returns no error, and rolls back when it returns one (which comes out of transaction) or a statement in it failed. A serialization failure or deadlock (40001, 40P01) runs body again, up to retries more times, so body must be safe to repeat. data is passed through, as Jai procedures capture nothing.

Not run: it needs a PostgreSQL server.

Parameters

pool: *Pool
the pool to borrow a connection from.
data: $T
passed to body.
body: (tx: *Connection, data: T) -> Pg_Error
the work, run on the transaction's connection.
isolation := Isolation.DEFAULT
the transaction's isolation level.
retries := 0
how many more times to run body after a serialization failure or deadlock.
read_only := false
start the transaction READ ONLY.

Returns

Pg_Error
Example
Transfer :: struct { from: s64; to: s64; amount: s64; }
error := Pg.transaction(pool, Transfer.{ 1, 2, 10 }, (tx: *Pg.Connection, t: Transfer) -> Pg.Pg_Error {
    _, error := Pg.query_dynamic(tx, "update accounts set balance = balance - $1 where id = $2", t.amount, t.from);
    if error.kind != .NONE return error;
    _, error = Pg.query_dynamic(tx, "update accounts set balance = balance + $1 where id = $2", t.amount, t.to);
    return error;
}, .SERIALIZABLE, retries = 3);

Not run: the example is marked ignore.

transaction :: (
    pool: *Pool,
    body: (tx: *Connection) -> Pg_Error,
    isolation := Isolation.DEFAULT,
    retries := 0,
    read_only := false
) -> Pg_Error

transaction for a body that needs no data.

Parameters

pool: *Pool
the pool to borrow a connection from.
body: (tx: *Connection) -> Pg_Error
the work, run on the transaction's connection.
isolation := Isolation.DEFAULT
the transaction's isolation level.
retries := 0
how many more times to run body after a serialization failure or deadlock.
read_only := false
start the transaction READ ONLY.

Returns

Pg_Error
transaction :: (
    c: *Connection,
    data: $T,
    body: (tx: *Connection, data: T) -> Pg_Error,
    isolation := Isolation.DEFAULT,
    retries := 0,
    read_only := false
) -> Pg_Error

The same on a connection of your own.

Parameters

c: *Connection
the connection. It must not be in a transaction.
data: $T
passed to body.
body: (tx: *Connection, data: T) -> Pg_Error
the work, run on c.
isolation := Isolation.DEFAULT
the transaction's isolation level.
retries := 0
how many more times to run body after a serialization failure or deadlock.
read_only := false
start the transaction READ ONLY.

Returns

Pg_Error
transaction :: (
    c: *Connection,
    body: (tx: *Connection) -> Pg_Error,
    isolation := Isolation.DEFAULT,
    retries := 0,
    read_only := false
) -> Pg_Error

transaction on your own connection, for a body that needs no data.

Parameters

c: *Connection
the connection. It must not be in a transaction.
body: (tx: *Connection) -> Pg_Error
the work, run on c.
isolation := Isolation.DEFAULT
the transaction's isolation level.
retries := 0
how many more times to run body after a serialization failure or deadlock.
read_only := false
start the transaction READ ONLY.

Returns

Pg_Error

See also

releaseping