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lo_write and lo_import does not work!

From: Miguel García <rocho08(at)yahoo(dot)es>
To: pgsql-interfaces(at)postgresql(dot)org
Subject: lo_write and lo_import does not work!
Date: 2007-04-18 13:34:40
Message-ID: 471146.38834.qm@web26607.mail.ukl.yahoo.com (view raw or flat)
Thread:
Lists: pgsql-interfaces
Hello,

I have a little trouble using large objects with libpq an postgresql 8.2 in windows xp professional SP2.

I want to save and load large objects from/to database, but its fails.

If i try to use the lo_import() function

#define FILE_IN "d:/question-icon.png"
Oid file_oid = lo_import (conn, FILE_IN);

file_oid always have 0 value, nevertheless the large object has been created in table
pg_largeobject, but has no data.

If i try to create the large object by hand, read the file from disk, and then write the binary data
to the large object, the call to lo_write() always fail (always returns -1):

    ifstream is;
    is.open (FILE_IN, ios::binary );

    // get length of file:
    is.seekg (0, ios::end);
    length = is.tellg();    
    is.seekg (0, ios::beg);

    // allocate memory:
    buffer = new char [length];

    // read data as a block:
    is.read (buffer,length);
    is.close();
                    
    /*
    * create the large object
    */    
    lobjId = lo_creat(conn, INV_WRITE);
    if (lobjId == 0) {
        fprintf(stderr, "no se pudo crear el objeto grande\n");
        exit_nicely (conn);
    }
    
    lobj_fd = lo_open(conn, lobjId, INV_WRITE);

    /*
    * Write the content of the file to the large object
    */
    tmp = lo_write(conn, lobj_fd, buffer, length);
    if (tmp < length) {
        fprintf(stderr, "error al escribir el objeto grande: %d bytes escritos\n", tmp);
        exit_nicely (conn);
    }    

In this case, the call to lo_write() does not work, but i can see the large object created in table
pg_largeobject.

Any Idea?




       
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Next:From: Alvaro HerreraDate: 2007-04-18 14:02:47
Subject: Re: lo_write and lo_import does not work!
Previous:From: Alvaro HerreraDate: 2007-04-17 13:07:04
Subject: Re: Implementing Frontend/Backend Protocol

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