# pg_lo_truncate

(PHP 5 >= 5.6.0, PHP 7, PHP 8)

pg_lo_truncate — Truncates a large object

### 说明

pg_lo_truncate(PgSql\Lob `$lob`, int `$size`): bool

pg_lo_truncate() truncates an PgSql\Lob instance.

To use the large object interface, it is necessary to enclose it within a transaction block.

### 参数

`lob`

  通过 pg_lo_open() 返回的 PgSql\Lob 实例。

`size`

  The number of bytes to truncate.

### 返回值

成功时返回 `true`， 或者在失败时返回 `false`。

### 更新日志

版本 | 说明
--- | ---
8.1.0 | 现在 `lob` 接受 PgSql\Lob 实例，之前接受 resource。

### 示例

示例 #1 pg_lo_truncate() example

`<?php
$doc_oid = 189762345;
$database = pg_connect("dbname=jacarta");
pg_query($database, "begin");
$handle = pg_lo_open($database, $doc_oid, "r");
// Truncate to 0
pg_lo_truncate($handle, 0);
pg_query($database, "commit");
echo $data;
?>`

### 参见

- pg_lo_tell() - 返回当前大型对象的指针位置

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