CODEWITHSUNDEEP
databaseapipostgresql
zefciu
zefciu

Reputation: 2046

Obtaining the size of lobject in PostgreSQL

I wonder why is there no function to directly obtain the size of large object in PostgreSQL. I believe one can seek() the end of object and then tell() the position, but isn't it too expensive? I can't find any info about it in google? So what is the proper way to obtain the size of lobject e.g. if you want to fill the Content-Size http header?

Upvotes: 1

Views: 2012

Answers (1)

Daniel Vérité
Daniel Vérité

Reputation: 61506

This function has been efficient enough for me, you may want to try it with you data:

CREATE OR REPLACE FUNCTION lo_size(oid) RETURNS integer 
AS $$ 
declare 
 fd integer; 
 sz integer; 
begin 
 fd = lo_open($1, 262144);
 if (fd<0) then
   raise exception 'Failed to open large object %', $1;
 end if;
 sz=lo_lseek(fd,0,2);
 if (lo_close(fd)!=0) then
   raise exception 'Failed to close large object %', $1;
 end if;
 return sz;
end; 
$$ LANGUAGE 'plpgsql';

Another option is select sum(length(data)) from pg_largeobject where loid=the_oid but it requires read access to pg_largeobject which I think has been suppressed in pg 9.0+ for non-superusers

Upvotes: 8

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