I had no answer from <span class="hb"><span class="g2">pgsql-general, so I'm reposting here.</span></span><br /><br
/>Hello,<br/>I would like to receive comments/suggestions about this project: <a
href="http://github.com/drotiro/postpic"target="_blank">http://github.com/drotiro/postpic</a>.<br /><br />In short,
it'san extension that enables image processing within the database, adding a new type (image) and several functions.<br
/>The SQL and Java interfaces are documented on the project's wiki, so I'm not talking about these here, but instead
presentsome detail on the datatype's implementation.<br /><br /> The image is represented by a struct containing some
attributes(dimensions, some exif tag: shoot date, exposure time...) and a large object holding the actual image data.
<br/>The idea is to have attributes stored directly to allow for efficient searching, while the large object seemed a
reasonablechoice to store the possibly large image data (what are the LOBs for?).<br /> With the current large objects
implementation,when a new lo is created it "lives" in the pg_largeobjects table, until someone calls lo_unlink on it.
Inmy case: I create the lo on behalf of the user, then store its oid in the image's internal representation. At this
point,the image can be inserted in a table, processed and so on, but when it gets deleted the corresponding lo remains
dangling,unless someone or something (eg. a trigger) takes care on destroying it.<br /> Is there a way of placing some
kindof hook on an object's deletion? A clean way to do a reference counting on large objects?<br />To avoid polluting
pg_largeobjects,almost all of the image processing functions in PostPic return a 'temporary_image' object, which is
justan alias on bytea. (Btw: I defined it using a DOMAIN. A better way?). Temporary images can be converted back to
imageswhen needed via a cast (often there is a variant of the function doing this automatically).<br /><br />Thanks in
advancefor your suggestions and contribution,<br /><font color="#888888">Domenico.</font>