320 lines
9.7 KiB
Markdown
320 lines
9.7 KiB
Markdown
Rust-Postgres
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=============
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A native PostgreSQL driver for Rust.
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Documentation is available at http://www.rust-ci.org/sfackler/rust-postgres/doc/postgres/.
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[](https://travis-ci.org/sfackler/rust-postgres)
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Overview
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========
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Rust-Postgres is a pure-Rust frontend for the popular PostgreSQL database. It
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exposes a high level interface in the vein of JDBC or Go's `database/sql`
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package.
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```rust
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extern crate postgres;
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extern crate time;
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use time::Timespec;
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use postgres::{PostgresConnection, NoSsl};
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use postgres::types::ToSql;
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struct Person {
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id: i32,
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name: ~str,
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time_created: Timespec,
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data: Option<~[u8]>
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}
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fn main() {
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let conn = PostgresConnection::connect("postgres://postgres@localhost",
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&NoSsl).unwrap();
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conn.execute("CREATE TABLE person (
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id SERIAL PRIMARY KEY,
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name VARCHAR NOT NULL,
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time_created TIMESTAMP NOT NULL,
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data BYTEA
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)", []).unwrap();
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let me = Person {
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id: 0,
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name: ~"Steven",
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time_created: time::get_time(),
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data: None
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};
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conn.execute("INSERT INTO person (name, time_created, data)
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VALUES ($1, $2, $3)",
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[&me.name as &ToSql, &me.time_created as &ToSql,
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&me.data as &ToSql]).unwrap();
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let stmt = conn.prepare("SELECT id, name, time_created, data FROM person")
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.unwrap();
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for row in stmt.query([]).unwrap() {
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let person = Person {
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id: row[1],
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name: row[2],
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time_created: row[3],
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data: row[4]
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};
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println!("Found person {}", person.name);
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}
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}
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```
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Requirements
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============
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* **Rust** - Rust-Postgres is developed against the *master* branch of the Rust
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repository. It will most likely not build against the releases on
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http://www.rust-lang.org.
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* **PostgreSQL 7.4 or later** - Rust-Postgres speaks version 3 of the
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PostgreSQL protocol, which corresponds to versions 7.4 and later. If your
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version of Postgres was compiled in the last decade, you should be okay.
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Usage
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=====
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Connecting
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----------
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Connect to a Postgres server using the standard URI format:
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```rust
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let conn = try!(PostgresConnection::connect("postgres://user:pass@host:port/database?arg1=val1&arg2=val2",
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&NoSsl));
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```
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`pass` may be omitted if not needed. `port` defaults to `5432` and `database`
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defaults to the value of `user` if not specified. The driver supports `trust`,
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`password`, and `md5` authentication.
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Statement Preparation
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---------------------
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Prepared statements can have parameters, represented as `$n` where `n` is an
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index into the parameter array starting from 1:
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```rust
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let stmt = try!(conn.prepare("SELECT * FROM foo WHERE bar = $1 AND baz = $2"));
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```
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Querying
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--------
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A prepared statement can be executed with the `query` and `execute` methods.
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Both methods take an array of parameters to bind to the query represented as
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`&ToSql` trait objects. `execute` returns the number of rows affected by the
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query (or 0 if not applicable):
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```rust
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let stmt = conn.prepare("UPDATE foo SET bar = $1 WHERE baz = $2");
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let updates = stmt.execute([&1i32 as &ToSql, & &"biz" as &ToSql]);
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println!("{} rows were updated", updates);
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```
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`query` returns an iterator over the rows returned from the database. The
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fields in a row can be accessed either by their indices or their column names,
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though access by index is more efficient. Like statement parameters, result
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columns are one-indexed.
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```rust
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let stmt = try!(conn.prepare("SELECT bar, baz FROM foo"));
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for row in try!(stmt.query([])) {
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let bar: i32 = row[1];
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let baz: ~str = row["baz"];
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println!("bar: {}, baz: {}", bar, baz);
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}
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```
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In addition, `PostgresConnection` has a utility `execute` method which is useful
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if a statement is only going to be executed once:
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```rust
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let updates = try!(conn.execute("UPDATE foo SET bar = $1 WHERE baz = $2",
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[&1i32 as &ToSql, & &"biz" as &ToSql]));
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println!("{} rows were updated", updates);
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```
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Transactions
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------------
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The `transaction` method will start a new transaction. It returns a
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`PostgresTransaction` object which has the functionality of a
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`PostgresConnection` as well as methods to control the result of the
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transaction:
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```rust
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let trans = try!(conn.transaction());
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try!(trans.execute(...));
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let stmt = try!(trans.prepare(...));
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if a_bad_thing_happened {
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trans.set_rollback();
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}
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if the_coast_is_clear {
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trans.set_commit();
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}
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drop(trans);
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```
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The transaction will be active until the `PostgresTransaction` object falls out
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of scope. A transaction will commit by default. Nested transactions are
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supported via savepoints.
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Connection Pooling
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------------------
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A very basic fixed-size connection pool is provided in the `pool` module. A
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single pool can be shared across tasks and `get_connection` will block until a
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connection is available.
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```rust
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let pool = try!(PostgresConnectionPool::new("postgres://postgres@localhost",
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NoSsl, 5));
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for _ in range(0, 10) {
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let pool = pool.clone();
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spawn(proc() {
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let conn = pool.get_connection();
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conn.query(...).unwrap();
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})
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}
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```
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Type Correspondence
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-------------------
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Rust-Postgres enforces a strict correspondence between Rust types and Postgres
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types. The driver currently supports the following conversions:
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<table>
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<thead>
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<tr>
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<td>Rust Type</td>
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<td>Postgres Type</td>
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</tr>
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</thead>
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<tbody>
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<tr>
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<td>bool</td>
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<td>BOOL</td>
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</tr>
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<tr>
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<td>i8</td>
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<td>"char"</td>
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</tr>
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<tr>
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<td>i16</td>
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<td>SMALLINT, SMALLSERIAL</td>
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</tr>
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<tr>
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<td>i32</td>
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<td>INT, SERIAL</td>
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</tr>
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<tr>
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<td>i64</td>
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<td>BIGINT, BIGSERIAL</td>
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</tr>
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<tr>
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<td>f32</td>
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<td>REAL</td>
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</tr>
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<tr>
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<td>f64</td>
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<td>DOUBLE PRECISION</td>
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</tr>
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<tr>
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<td>str</td>
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<td>VARCHAR, CHAR(n), TEXT</td>
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</tr>
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<tr>
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<td>[u8]</td>
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<td>BYTEA</td>
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</tr>
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<tr>
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<td>extra::json::Json</td>
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<td>JSON</td>
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</tr>
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<tr>
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<td>extra::uuid::Uuid</td>
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<td>UUID</td>
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</tr>
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<tr>
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<td>extra::time::Timespec</td>
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<td>TIMESTAMP, TIMESTAMP WITH TIME ZONE</td>
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</tr>
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<tr>
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<td>types::range::Range<i32></td>
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<td>INT4RANGE</td>
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</tr>
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<tr>
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<td>types::range::Range<i64></td>
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<td>INT8RANGE</td>
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</tr>
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<tr>
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<td>types::range::Range<Timespec></td>
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<td>TSRANGE, TSTZRANGE</td>
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</tr>
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<tr>
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<td>types::array::ArrayBase<Option<bool>></td>
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<td>BOOL[], BOOL[][], ...</td>
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</tr>
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<tr>
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<td>types::array::ArrayBase<Option<~[u8]>></td>
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<td>BYTEA[], BYTEA[][], ...</td>
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</tr>
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<tr>
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<td>types::array::ArrayBase<Option<i8>></td>
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<td>"char"[], "char"[][], ...</td>
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</tr>
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<tr>
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<td>types::array::ArrayBase<Option<i16>></td>
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<td>INT2[], INT2[][], ...</td>
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</tr>
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<tr>
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<td>types::array::ArrayBase<Option<i32>></td>
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<td>INT4[], INT4[][], ...</td>
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</tr>
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<tr>
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<td>types::array::ArrayBase<Option<~str>></td>
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<td>TEXT[], CHAR(n)[], VARCHAR[], TEXT[][], ...</td>
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</tr>
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<tr>
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<td>types::array::ArrayBase<Option<Json>></td>
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<td>JSON[], JSON[][], ...</td>
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</tr>
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<tr>
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<td>types::array::ArrayBase<Option<i64>></td>
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<td>INT8[], INT8[][], ...</td>
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</tr>
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<tr>
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<td>types::array::ArrayBase<Option<Timespec>></td>
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<td>TIMESTAMP[], TIMESTAMPTZ[], TIMESTAMP[][], ...</td>
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</tr>
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<tr>
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<td>types::array::ArrayBase<Option<f32>></td>
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<td>FLOAT4[], FLOAT4[][], ...</td>
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</tr>
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<tr>
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<td>types::array::ArrayBase<Option<f64>></td>
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<td>FLOAT8[], FLOAT8[][], ...</td>
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</tr>
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<tr>
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<td>types::array::ArrayBase<Option<Uuid>></td>
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<td>UUID[], UUID[][], ...</td>
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</tr>
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<tr>
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<td>types::array::ArrayBase<Option<Range<i32>>></td>
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<td>INT4RANGE[], INT4RANGE[][], ...</td>
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</tr>
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<tr>
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<td>types::array::ArrayBase<Option<Range<Timespec>>></td>
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<td>TSRANGE[], TSTZRANGE[], TSRANGE[][], ...</td>
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</tr>
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<tr>
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<td>types::array::ArrayBase<Option<Range<i64>>></td>
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<td>INT8RANGE[], INT8RANGE[][], ...</td>
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</tr>
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<tr>
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<td>std::hashmap::HashMap<~str, Option<~str>></td>
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<td>HSTORE</td>
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</tr>
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</tbody>
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</table>
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More conversions can be defined by implementing the `ToSql` and `FromSql`
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traits.
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Development
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===========
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Like Rust itself, Rust-Postgres is still in the early stages of development, so
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don't be surprised if APIs change and things break. If something's not working
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properly, file an issue or submit a pull request!
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