Pdo\Pgsql::lobCreate

Creates a new large object

説明

public stringfalse Pdo\Pgsql::lobCreate()

Pdo\Pgsql::lobCreate creates a large object and returns the OID which refers to it. It can be opened to read or write data with Pdo\Pgsql::lobOpen.

The OID can be stored in columns of type OID and be used to reference the large object, without causing the row to grow arbitrarily large. The large object will continue to live in the database until it is removed by calling Pdo\Pgsql::lobUnlink.

Large objects are cumbersome to use. Indeed, it is required that Pdo\Pgsql::lobUnlink is called prior to deleting the last row referencing the OID in the entire database; otherwise, unreferenced large objects will remain on the server indefinitely. Moreover, large objects have no access controls. An alternative is the bytea column type, which can be up to 1GB in size, and this column type transparently manages the storage for optimal row size.

注意: This function, and all manipulations of the large object, must be called and carried out within a transaction.

パラメータ

この関数にはパラメータはありません。

戻り値

Returns the OID of the newly created large object on success, 失敗した場合に false を返します.

例

例1 Pdo\Pgsql::lobCreate example

This example creates a new large object and copies the contents of a file into it. The OID is then stored into a table.

<?php
$db = new Pdo\Pgsql('pgsql:dbname=test host=localhost', $user, $pass);
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$db->beginTransaction();
$oid = $db->lobCreate();
$stream = $db->lobOpen($oid, 'w');
$local = fopen($filename, 'rb');
stream_copy_to_stream($local, $stream);
$local = null;
$stream = null;
$stmt = $db->prepare("INSERT INTO BLOBS (ident, oid) VALUES (?, ?)");
$stmt->execute([$some_id, $oid]);
$db->commit();
?>

参考

Pdo\Pgsql::lobOpen
Pdo\Pgsql::lobUnlink
pg_lo_create
pg_lo_open