Be careful: pg_lo_export() create empty file without "begin"/"end".
See docs: "...it is necessary to enclose it within a transaction block..."(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)
pg_lo_read — Read a large object
   pg_lo_read() reads at most
   length bytes from a large object and
   returns it as a string.
  
To use the large object interface, it is necessary to enclose it within a transaction block.
Зауваження:
This function used to be called pg_loread().
lobПримірник PgSql\Lob, якого повертає pg_lo_open().
lengthAn optional maximum number of bytes to return.
   A string containing length bytes from the
   large object, or false on error.
  
| Версія | Опис | 
|---|---|
| 8.1.0 | Тепер параметр lobмає бути примірником
  PgSql\Lob. Раніше очікувався resource. | 
Приклад #1 pg_lo_read() example
<?php
   $doc_oid = 189762345;
   $database = pg_connect("dbname=jacarta");
   pg_query($database, "begin");
   $handle = pg_lo_open($database, $doc_oid, "r");
   $data = pg_lo_read($handle, 50000);
   pg_query($database, "commit");
   echo $data;
?>Be careful: pg_lo_export() create empty file without "begin"/"end".
See docs: "...it is necessary to enclose it within a transaction block..."