pg_lo_write
(PHP 4 >= 4.2.0, PHP 5, PHP 7)
pg_lo_write — Записывает данные в большой объект
Описание
$large_object
, string $data
[, int $len
] )pg_lo_write() записывает данные в большой объект, начиная с текущей позиции внутреннего указателя.
Операции с использованием интерфейса больших объектов необходимо заключать в блок транзакции.
Замечание:
Прежнее название функции: pg_lowrite().
Список параметров
-
large_object -
Ресурс большого объекта (LOB) PostgreSQL, возвращаемый функцией pg_lo_open().
-
data -
Данные для записи в большой объект. Если аргумент
lenзадан и меньше размераdata, то записаны будут толькоlenбайт. -
len -
Необязательный аргумент. Максимальное количество записываемых байт. Должен быть больше нуля и не превышать размер
data. По умолчанию принимается равным размеруdata.
Возвращаемые значения
Количество записанных в большой объект байт, либо FALSE в случае ошибки.
Примеры
Пример #1 Пример использования pg_lo_write()
<?php
$doc_oid = 189762345;
$data = "This will overwrite the start of the large object.";
$database = pg_connect("dbname=jacarta");
pg_query($database, "begin");
$handle = pg_lo_open($database, $doc_oid, "w");
$data = pg_lo_write($handle, $data);
pg_query($database, "commit");
?>
Смотрите также
- pg_lo_create() - Создает большой объект
- pg_lo_open() - Открывает большой объект базы данных
- PHP Руководство
- Функции по категориям
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- Справочник функций
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- Расширения для работы с базами данных отдельных производителей
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Коментарии
Be aware when you modify a lo with pg_lowrite() to remove first the old one : if the new lo is smaller than the one before, it only overwrite the begining and you keep the end of the old lo (open with "w" parameter, PHP 4.04 Linux RH).Using php 4.3.0 and PostgreSQL 7.3.1
I can write a simple script in which pg_lo_write seems to always return 1 and not the number of bytes written, as evidenced by extracting the data through another means.
Further more, I can make this pg_lo_write fail, or at least fail to write all the data it's pretty difficult to tell without the number of bytes written being returned, and not return the false value. In addition to this, the lo resource has been adjusted so that the oid it contains is 0.
Unfortunately, I do not know what exactly the failure mode is, it does seem to be in the ip network communication side of PostgreSQL, which is odd since the unix domain comms works fine for this. However, it would have been useful to have the pg_lo_write() function return as advertised, it would have saved some of the 2 man hours me and the dev. team put into diagnosing this problem.