Re: Tuple concurrency issue in large objects

Hi Rene,

I am using Postgresql 11.2. Major version is 11 and minor version is 2.


On 12/10/2019 11:24 AM, Rene Romero Benavides wrote:
> Hi Shalini. The usual diagnostic info is your postgresql server 
> version, major and minor version, such as in 12.1 , the major version 
> is 12 and the minor version (patch version) is 1.
>
>
> On Fri, Dec 6, 2019 at 9:26 AM Shalini <[email protected] 
> <mailto:[email protected]>> wrote:
>
>     Hi all,
>
>     I am working on a project which allows multiple users to work on
>     single
>     large text document. I am using lo_put to apply only the diff into
>     the
>     large object without replacing it with a new lob. While working on
>     it, I
>     encountered an error "Tuple concurrently updated".
>     The error can be reproduced with two psql clients.
>
>     Setup:
>
>     mydb=# create table text_docs(id serial primary key, data oid);
>     CREATE TABLE
>     mydb=# insert into text_docs(data) select lo_import('./upload.txt');
>     INSERT 0 1
>     mydb=# select * from text_docs;
>       id |  data
>     ----+---------
>        1 | 5810130
>     (1 rows)
>
>     Now, if we open two psql clients and execute the following commands:
>
>     Client 1:
>
>     mydb=# begin;
>     BEGIN
>     mydb=# select lo_put(5810130, 10, '\xaa');
>     UPDATE 1
>
>     Client 2:
>
>     mydb=# select lo_put(5810130, 10, '\xaa');
>
>     Client 1:
>     mydb=# commit;
>     COMMIT
>
>     Client 2:
>     mydb=# select lo_put(5810130, 10, '\xaa');
>     ERROR:  tuple concurrently updated
>
>     Is there a workaround to this concurrency issue without creating a
>     new
>     large object?
>
>     Regards
>     Shalini
>
>
>
>
>
>
> -- 
> El genio es 1% inspiración y 99% transpiración.
> Thomas Alva Edison
> http://pglearn.blogspot.mx/
>