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).
pg_lo_write
(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)
pg_lo_write — ラージオブジェクトを書く
説明
pg_lo_write(resource
$large_object, string $data, int $len = ?): intpg_lo_write() は、ラージオブジェクトの カレントのシーク位置にデータを書き込みます。
ラージオブジェクトインターフェイスは、トランザクションブロックの中で 使用する必要があります。
注意:
この関数は、以前は pg_lowrite() と呼ばれていました。
パラメータ
-
large_object -
pg_lo_open() によって返された PostgreSQL ラージオブジェクト (LOB) リソース。
-
data -
ラージオブジェクトに書き込むデータ。
lenがdataの長さより小さく指定されている場合、lenバイトのみが書き込まれます。 -
len -
書き込むデータの最大バイト数（オプション）。0 より大きく、かつ
dataのサイズ以下でなければなりません。 デフォルトはdataの長さです。
返り値
ラージオブジェクトに書き込んだバイト数を返します。
エラー時には false を返します。
例
例1 pg_lo_write() の例
<?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");
?>
add a note
User Contributed Notes 2 notes
cedric at isoca.com ¶
23 years ago
nandrews at logictree dot co dot uk ¶
20 years ago
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.
