Path: newssvr20.news.prodigy.com!newsmst01.news.prodigy.com!prodigy.com!pd7cy2so!pd7cy1no!shaw.ca!sjc70.webusenet.com!news.webusenet.com!sn-xit-02!sn-xit-04!sn-xit-01!sn-post-01!supernews.com!corp.supernews.com!not-for-mail From: Daniel Morgan Newsgroups: comp.databases.oracle.server Subject: Re: Can anybody explain this strange thing? Date: Thu, 01 Jan 2004 21:26:20 -0800 Organization: ATS Message-ID: <1073021093.278943@yasure> User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.4) Gecko/20030624 Netscape/7.1 (ax) X-Accept-Language: en-us, en MIME-Version: 1.0 References: <3FF4C746.6040001@skynet.be> In-Reply-To: <3FF4C746.6040001@skynet.be> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cache-Post-Path: yasure!unknown@oracle.advtechserv.com X-Cache: nntpcache 2.4.0b5 (see http://www.nntpcache.org/) X-Complaints-To: abuse@supernews.com Lines: 56 Xref: newssvr20.news.prodigy.com comp.databases.oracle.server:251129 Gerard H. Pille wrote: > vic wrote: > >> I have 2 servers, server a is HP (DSS) and server b is Sun. Now one >> of the >> applications among these 2 servers is to query server b from server a. >> server a has a user, which has a dblink to connect to server b. The >> strange >> thing is: >> If I query server a from server b using sqlplus as: >> sql> conn user/password@b from server a and run query, e.g. >> sql> select ... from table1 , table2 where.... The elapsed time is 10 >> seconds but if I use a user in server b and use its dblink (svra) to run: >> sql > select ... from table1@svra , table2@svra where.... the elased >> time is >> 4 minutes. >> The listener.ora for server a has an entry as sdu=32768 and >> tnsnames.ora in >> server b (hp) has also sdu=32768 as its entry. I set tdu for both the >> same >> as sdu. It is still the same. Theoritically they should have the same >> response time. Why using sqlplus is faster than using dblink? The >> dblink >> user is also the same user I connect from server a with sqlplus and >> the same >> connect string as the using clause in dblink. I couldn't figure out. I >> think it is strange. Does anyone have the same strange experience as >> mine? >> Has anyone ever tackled this issue and willing to share it with me and >> others? >> >> Thanks in advance. >> >> > > It's not strange: using the db-link, Oracle may need to fetch both > tables completely, and will then join (where-clause) on server b. In > the first case, the action happens on server a, only the results are > transferred. > Take a look at the hint "DRIVING_SITE in the form: SELECT /*+DRIVING_SITE(dept)*/ e.empno, e.empname FROM emp e, dept@RSITE d WHERE e.deptno = d.deptno; It may solve the problem. -- Daniel Morgan http://www.outreach.washington.edu/ext/certificates/oad/oad_crs.asp http://www.outreach.washington.edu/ext/certificates/aoa/aoa_crs.asp damorgan@x.washington.edu (replace 'x' with a 'u' to reply)