Date: Sun, 17 Jan 2016 23:08:06 +0100 (CET)
From: Andreas Joseph Krogh <andreas@visena.com>
To: pgsql-sql@postgresql.org
Message-ID: <VisenaEmail.a5.57089a2d41817e3c.152519d26b3@tc7-visena>
In-Reply-To: <825207667.6348678.1453058794606.JavaMail.yahoo@mail.yahoo.com>
Subject: Re: BLOBs
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P=C3=A5 s=C3=B8ndag 17. januar 2016 kl. 20:26:34, skrev Eugene Yin <eugeney=
mail@ymail.com=20
<mailto:eugeneymail@ymail.com>>:
=C2=A0
BLOB binary large object see Large Object Support=20
<http://www.postgresql.org/docs/current/static/largeobjects.html>
=C2=A0
=C2=A0

 * =C2=A0Minuses=20
 * must use different interface from what is normally used to access BLOBs.=
=20
 * Need to track OID. Normally a separate table with additional meta data i=
s=20
used to describe what each OID is.=20
 * (8.4 and <8.4) No access controls in database.=20
 * Sometimes advised against=20
<http://www.postgresql.org/message-id/20150129142450.b83ce5d0652c39791292d0=
d5@potentialtech.com>
 (basically you only need them if your entry is so large you need/want to s=
eek=20
and read bits and pieces of it at a time).=C2=A0=20
https://wiki.postgresql.org/wiki/BinaryFilesInDB=20
<https://wiki.postgresql.org/wiki/BinaryFilesInDB>
=C2=A0
=C2=A0
Do one really:=C2=A0

 * Need to track OID. Normally a separate table with additional meta data i=
s=20
used to describe what each OID is.=20
=C2=A0
Using BLOBs and PG's OIDs is really simple if you use the pgjdbc-ng driver.
=C2=A0
You column has to be defined as type=3DOID, like this
=C2=A0
CREATE TABLE my_stuff(
id SERIAL PRIMARY KEY,
data OID
);
=C2=A0
Then use the JDBC BLOB-interface as defined.
=C2=A0
You don't need to do anything else except running the 'vacuumlo'=20
system-command (not SQL-command) once in a while, preferably using 'cron' o=
r=20
some other scheduling-tool.
=C2=A0
Note that "everything" you read about PG and JDBC and BLOB will describe th=
e=20
official JDBC-driver, which doesn't even support BLOBs. So if you just get =
by=20
that and use the pgjdbc-ng driver your life will be much simpler.
=C2=A0
-- Andreas Joseph Krogh
CTO / Partner - Visena AS
Mobile: +47 909 56 963
andreas@visena.com <mailto:andreas@visena.com>
www.visena.com <https://www.visena.com>
 <https://www.visena.com>


=C2=A0

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<div>P=C3=A5 s=C3=B8ndag 17. januar 2016 kl. 20:26:34, skrev Eugene Yin &lt=
;<a href=3D"mailto:eugeneymail@ymail.com">eugeneymail@ymail.com</a>&gt;:</d=
iv>

<blockquote style=3D"border-left: 1px solid rgb(204, 204, 204); margin: 0pt=
 0pt 0pt 0.8ex; padding-left: 1ex;">
<div style=3D"color:#000; background-color:#fff; font-family:HelveticaNeue,=
 Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:13px=
">
<div dir=3D"ltr" id=3D"yui_3_16_0_1_1453003373099_22267">=C2=A0</div>

<div dir=3D"ltr" id=3D"yui_3_16_0_1_1453003373099_22267">BLOB binary large =
object see <a href=3D"http://www.postgresql.org/docs/current/static/largeob=
jects.html" id=3D"yui_3_16_0_1_1453003373099_22514" rel=3D"nofollow">Large =
Object Support</a></div>

<div dir=3D"ltr" id=3D"yui_3_16_0_1_1453003373099_22267">=C2=A0</div>

<div dir=3D"ltr" id=3D"yui_3_16_0_1_1453003373099_22267">=C2=A0</div>

<ul>
=09<li id=3D"yui_3_16_0_1_1453003373099_22538">=C2=A0Minuses</li>
</ul>

<ul dir=3D"ltr" id=3D"yui_3_16_0_1_1453003373099_22540">
=09<li id=3D"yui_3_16_0_1_1453003373099_22542">must use different interface=
 from what is normally used to access BLOBs.</li>
=09<li id=3D"yui_3_16_0_1_1453003373099_22544"><b id=3D"yui_3_16_0_1_145300=
3373099_22589">Need to track OID. Normally a separate table with additional=
 meta data is used to describe what each OID is. </b></li>
=09<li id=3D"yui_3_16_0_1_1453003373099_22546">(8.4 and &lt;8.4) No access =
controls in database.</li>
=09<li id=3D"yui_3_16_0_1_1453003373099_22548">Sometimes <a href=3D"http://=
www.postgresql.org/message-id/20150129142450.b83ce5d0652c39791292d0d5@poten=
tialtech.com" id=3D"yui_3_16_0_1_1453003373099_22550" rel=3D"nofollow">advi=
sed against</a> (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).=C2=A0</li>
</ul>

<div dir=3D"ltr" id=3D"yui_3_16_0_1_1453003373099_22267"><span id=3D"yui_3_=
16_0_1_1453003373099_22319"><a class=3D"edited-link-editor" href=3D"https:/=
/wiki.postgresql.org/wiki/BinaryFilesInDB" id=3D"yui_3_16_0_1_1453003373099=
_22317">https://wiki.postgresql.org/wiki/BinaryFilesInDB</a></span></div>

<div id=3D"yui_3_16_0_1_1453003373099_22267">=C2=A0</div>

<div id=3D"yui_3_16_0_1_1453003373099_22267">=C2=A0</div>

<div id=3D"yui_3_16_0_1_1453003373099_22267">Do one really:=C2=A0</div>

<ul dir=3D"ltr" id=3D"yui_3_16_0_1_1453003373099_22540">
=09<li id=3D"yui_3_16_0_1_1453003373099_22544"><b id=3D"yui_3_16_0_1_145300=
3373099_22589">Need to track OID. Normally a separate table with additional=
 meta data is used to describe what each OID is.</b></li>
</ul>
</div>
</blockquote>

<div>=C2=A0</div>

<div>Using BLOBs and PG's OIDs is really simple if you use the pgjdbc-ng dr=
iver.</div>

<div>=C2=A0</div>

<div>You column has to be defined as type=3DOID, like this</div>

<div>=C2=A0</div>

<div>CREATE TABLE my_stuff(</div>

<div>id SERIAL PRIMARY KEY,</div>

<div><strong>data OID</strong></div>

<div>);</div>

<div>=C2=A0</div>

<div>Then use the JDBC BLOB-interface as defined.</div>

<div>=C2=A0</div>

<div>You don't need to do<em> </em>anything else <em>except</em> running th=
e 'vacuumlo' system-command (not SQL-command) once in a while, preferably u=
sing 'cron' or some other scheduling-tool.</div>

<div>=C2=A0</div>

<div>Note that &quot;everything&quot; you read about PG and JDBC and BLOB w=
ill 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 muc=
h simpler.</div>

<div>=C2=A0</div>

<div class=3D"origo-email-signature">
<div>--
<div><span style=3D"font-family:arial,helvetica,sans-serif;"><strong>Andrea=
s Joseph Krogh</strong></span></div>

<div><span style=3D"font-family:arial,helvetica,sans-serif;">CTO / Partner<=
/span> - Visena AS</div>

<div><span style=3D"font-family:arial,helvetica,sans-serif;">Mobile: +47 90=
9 56 963</span></div>

<div><a href=3D"mailto:andreas@visena.com">andreas@visena.com</a></div>

<div><a href=3D"https://www.visena.com">www.visena.com</a></div>

<div style=3D"padding-top: 5px"><a href=3D"https://www.visena.com"><img alt=
=3D"" src=3D"cid:part_F1521635891994D6Q3V"></a></div>
</div>
</div>

<div>=C2=A0</div>
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