Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!aioe.org!.POSTED!not-for-mail From: Abu Yahya Newsgroups: comp.lang.java.programmer,comp.programming,comp.lang.java.databases Subject: Re: Storing large strings for future equality checks Date: Wed, 08 Jun 2011 23:45:33 +0530 Organization: Aioe.org NNTP Server Lines: 18 Message-ID: References: NNTP-Posting-Host: LePVoNEtezBuiMA9+cM5gA.user.speranza.aioe.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Complaints-To: abuse@aioe.org User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2.17) Gecko/20110414 Thunderbird/3.1.10 X-Notice: Filtered by postfilter v. 0.8.2 Xref: x330-a1.tempe.blueboxinc.net comp.lang.java.programmer:5124 comp.programming:442 comp.lang.java.databases:464 On 6/8/2011 10:58 PM, Willem wrote: > markspace wrote: > ) On 6/8/2011 9:35 AM, Abu Yahya wrote: > )> I considered using an SHA-512 hash of these strings and storing them in > )> the database. However, while these will save on storage space, it will > )> take time to do the hashing before comparing an incoming string. So I'm > )> still wasting time. (Collisions due to hashing will not be a problem, > )> since an occasional false positive will not be fatal for my application). > ) > ) You have to store the whole string. Even if the SHA-512 hash codes are > ) equal, it could be that the strings are different. You'll have to > ) eventually compare the raw string, even if the SHA is used as a > ) quick-out case. > > No he doesn't. Read again. Especially the last bit between parentheses. > Yeah, it seems he missed that last part or read it incorrectly.