Path: news.easynews.com!newsfeed1.easynews.com!easynews.com!easynews!newsfeed.news2me.com!newsfeed2.earthlink.net!newsfeed.earthlink.net!stamper.news.pas.earthlink.net!newsread1.prod.itd.earthlink.net.POSTED!not-for-mail Message-ID: <3DF81FBC.1070100@earthlink.net> From: Jonathan Leffler Organization: Chaotic Sputterings User-Agent: Mozilla/5.0 (Macintosh; U; PPC Mac OS X; en-US; rv:1.0.1) Gecko/20020823 Netscape/7.0 X-Accept-Language: en-us, en MIME-Version: 1.0 Newsgroups: comp.databases.theory Subject: Re: issues bout storage References: <2262848.1039536123@dbforums.com> <3DF6D91D.9070000@earthlink.net> <2267675.1039619325@dbforums.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Lines: 26 Date: Thu, 12 Dec 2002 05:34:37 GMT NNTP-Posting-Host: 66.47.74.12 X-Complaints-To: abuse@earthlink.net X-Trace: newsread1.prod.itd.earthlink.net 1039671277 66.47.74.12 (Wed, 11 Dec 2002 21:34:37 PST) NNTP-Posting-Date: Wed, 11 Dec 2002 21:34:37 PST Xref: newsfeed1.easynews.com comp.databases.theory:24059 X-Received-Date: Wed, 11 Dec 2002 22:35:21 MST (news.easynews.com) fanquyin wrote: > 2. what buffer replacement policy will you use if the buffer can contain > 5 employee records at a time and the user tries to sort employees by > their SSN? > Make sure I have more than 200 buffers available so it all fits > in memory. > > --I'm sure there is enough buffer space. > -- Do I need to consider about least used, most used records. or things > like that for the buffer replacement? It depends on what else is demanding the use of those buffers. If all the data in the database is in your employee table, then it matters not at all which, if any, replacement algorithm you use. If you need to share those buffers with other tables, then the optimal buffer replacement algorithm is to evict from cache the pages that won't be used for the longest time. The hard part is working out which pages those are. Remember: past performance is not a reliable indicator of what will happen in the future (but it's the best you've got to work with). -- Jonathan Leffler #include Email: jleffler@earthlink.net, jleffler@us.ibm.com Guardian of DBD::Informix 1.04.PC1 -- http://dbi.perl.org/