java - PostgreSQL - integer[] best practice -

-

working on web app lately decided use integer[] in data model. having 2 tables, 1 articles' data , second tags (tag id , description), decided tag ids article tagged in article.tags integer[] column.

as milen a. radev pointed out:

tip: arrays not sets; searching specific array elements can sign of database misdesign. consider using separate table row each item array element. easier search, , scale better large number of elements.

not that, having work integer[] using jdbc , ibatis turned out, shall "interesting".

for moment, can away working implementation in place had do. re-worked simplicity's sake using separate table storing article.id , tag.id relationships.

in end i'm puzzled integer[] best used , in context?

i think figured out hard way it's not best for.

imho, since array violation of 1nf, best context is:... (drumroll)..... none.

this gets question of why have data not meant queried. values potentially searchable, , if not supposed use array on searchable values, again led conclusion never worth using.

this leaves hypothetical case storing array solely purpose of analysis , manipulation on client. i'm sure these exist, not in experience.

edit: above said, "i'm sure these exist..." @ @mu short's answer example.


Comments

Post a Comment

Popular posts from this blog

java - SNMP4J General Variable Binding Error -

-
i trying use snmp4j snmp bulkget. when ever use snmp4j make call returned responseevent error says "general variable binding error" , data returned equal null. to debug: print out, console, exact oid , version number using in snmp4j. use printed out data snmpwalk on command line. valid results. know sending snmp4j correct pdu correct oid, version number, max repititions, etc. i have used snmp4j , code wrote succesffuly monitor other devices years. don't know different time. leaving me stumped. why "general variable binding error?" causes error? ideas debug? can reproduced? if so, first action should using wireshark or microsoft network monitor capture network packets. my guess agent gives generr response, not surprising, http://www.ietf.org/rfc/rfc1157.txt
Read more

windows - Python Service Installation - "Could not find PythonClass entry" -

-
i working on building python service. inducing error, not sure inducing it. ps c:\...> python .\file.py debug debugging service myservice - press ctrl+c stop. error 0xc00000f4 - not find service's pythonclass entry in registry error 1814 - specified resource name cannot found in image file. error 0xc0000080 - not locate module name in python class string (ie, no '.') this error coming pythonservicemessages.mc in pythonwin32. it turns out error result caused exception being thrown , python script dying off.
Read more

Determine if a XmlNode is empty or null in C#? -

-
the following code takes xmlnode data type , populates dataset object xmlnode content. write dataset's content file. public void populatedataset(xmlnode node) { xmlnodereader reader = new xmlnodereader(node); dataset ds = new dataset(); ds.readxml(reader); system.guid guid = system.guid.newguid(); string name = string.format("{0}{1}_{2}.xml", utility.xmloutputpath, utility.xmloutputfilename, guid.tostring()); //need write "node empty" file if xmlnode object empty of null ds.writexml(name, xmlwritemode.ignoreschema); } the problem encountered 1 scenario not write content file. how determine if xmlnode object null or empty? you can check if node parameter null or has innertext or innerxml properties null or empty, when enter method before creating xmlnodereader .
Read more