Message-ID: <52602FBA.50303@archidevsys.co.nz>
Date: Fri, 18 Oct 2013 07:43:06 +1300
From: Gavin Flower <GavinFlower@archidevsys.co.nz>
Organization: ArchiDevSys
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To: Alvaro Herrera <alvherre@2ndquadrant.com>,
 Gary Stainburn <gary.stainburn@ringways.co.uk>
CC: "pgsql-sql@postgresql.org" <pgsql-sql@postgresql.org>
Subject: Re: Advice - indexing on varchar fields where only last x characters
 known
References: <201310171220.44550.gary.stainburn@ringways.co.uk>
 <20131017183902.GA4943@eldon.alvh.no-ip.org>
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On 18/10/13 07:39, Alvaro Herrera wrote:
> Gary Stainburn wrote:
>
>> The problem that I have is that these VIN numbers are provided by a number of
>> data systems including manufacturer feeds, logistics companies as well as
>> internal systems. Some use the full 17 character string while others only use
>> the last 11.
>>
>> On top of this, my users are used to only having to type the last 6 characters
>> for speed and usability reasons.
> Try creating an index on reverse(vin) and using the same function in
> queries; you can put a % at the end of the sought-for literal to match
> suffixes.  That works quite well and is very simple to implement.
>
That is extremely cunning,
and obvious in retrospect! :-)


Cheers,
Gavin


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