Re: BLOBs

På søndag 17. januar 2016 kl. 20:26:34, skrev Eugene Yin <eugeneymail(at)ymail(dot)com
<mailto:eugeneymail(at)ymail(dot)com>>:
 
BLOB binary large object see Large Object Support
<http://www.postgresql.org/docs/current/static/largeobjects.html>
 
 

*  Minuses
* must use different interface from what is normally used to access BLOBs.
* Need to track OID. Normally a separate table with additional meta data is
used to describe what each OID is.
* (8.4 and <8.4) No access controls in database.
* Sometimes advised against
<http://www.postgresql.org/message-id/20150129142450.b83ce5d0652c39791292d0d5@potentialtech.com>
(basically you only need them if your entry is so large you need/want to seek
and read bits and pieces of it at a time). 
https://wiki.postgresql.org/wiki/BinaryFilesInDB
<https://wiki.postgresql.org/wiki/BinaryFilesInDB>
 
 
Do one really: 

* Need to track OID. Normally a separate table with additional meta data is
used to describe what each OID is.
 
Using BLOBs and PG's OIDs is really simple if you use the pgjdbc-ng driver.
 
You column has to be defined as type=OID, like this
 
CREATE TABLE my_stuff(
id SERIAL PRIMARY KEY,
data OID
);
 
Then use the JDBC BLOB-interface as defined.
 
You don't need to do anything else except running the 'vacuumlo'
system-command (not SQL-command) once in a while, preferably using 'cron' or
some other scheduling-tool.
 
Note that "everything" you read about PG and JDBC and BLOB will describe the
official JDBC-driver, which doesn't even support BLOBs. So if you just get by
that and use the pgjdbc-ng driver your life will be much simpler.
 
-- Andreas Joseph Krogh
CTO / Partner - Visena AS
Mobile: +47 909 56 963
andreas(at)visena(dot)com <mailto:andreas(at)visena(dot)com>
www.visena.com <https://www.visena.com>
<https://www.visena.com>