RE:

Posted in 2001

John Carlson — Mon, 29 Jan 2001 10:43:11 -0500 — source: Informix-list mailing list archive (1991-1998)

This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. ------_=_NextPart_001_01C08A0A.2F4ED358 Content-Type: text/plain; charset="iso-8859-1" Have you run the required "UPDATE STATISTICS" for this table? Depending on the statistics in hand, it might think that the sequential scan might be quicker. -----Original Message----- From: shahid.mehmood [mailto:shahid.mehmood@aku.edu] Sent: Monday, January 29, 2001 7:58 AM To: informix-list@iiug. org (E-mail) Cc: shahid.mehmood Subject: OS: SCO UNIX 5.0, IX: OWS 7.20.UC2 I have a table named payprmbcalc which also has index on its three fields. This table contains 28000+ records. when I run a query on this table with the db engine searches the table using sequential scan, where as I am expecting search using an index. this query is taking too long to complete. can you guys suggest any thing how to improve this query ... The table schema and 'set explain on' output is attached here with. The Table Schema ... { TABLE "paydba".payprmbcalc row size = 58 number of columns = 9 index size = 36 } create table "paydba".payprmbcalc ( paymonth integer not null constraint "paydba".n196_305, internalno char(6) not null constraint "paydba".n196_306, currency char(10) not null constraint "paydba".n196_307, balance decimal(10,2), product decimal(10,2), taxprofit decimal(10,2), ntaxprofit decimal(10,2), lastedit date, lastuser char(10) ); create unique index "paydba".pp001idx on "paydba".payprmbcalc (paymonth,internalno, currency); the 'set explain output' ... QUERY: ------ select employee.employeeno , payprmbcalc.internalno, employee.fname , employee.mname , employee.lname , payprmbcalc.currency , payprmbcalc.balance , employee.appointment , employee.termination , payprmbcalc.product , payprmbcalc.taxprofit , payprmbcalc.ntaxprofit from payprmbcalc, employee where payprmbcalc.paymonth = 2000130000 and employee.internalno = payprmbcalc.internalno order by 1 Estimated Cost: 7 Estimated # of Rows Returned: 5 Temporary Files Required For: Order By 1) paydba.payprmbcalc: SEQUENTIAL SCAN { why ? i need index scan } Filters: paydba.payprmbcalc.paymonth = 2000130000 2) paydba.employee: INDEX PATH (1) Index Keys: internalno Lower Index Filter: paydba.employee.internalno = paydba.payprmbcalc.internalno an early reply will be highly appreciated. thanks. Shahid Mehmood Software Designer & IX DBA Information Systems Department The Aga Khan University, Karachi Official: Yes ------_=_NextPart_001_01C08A0A.2F4ED358 Content-Type: text/html; charset="iso-8859-1" <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1"> <TITLE></TITLE> <META content="MSHTML 5.00.3013.2600" name=GENERATOR></HEAD> <BODY> <DIV>Have you run the required "UPDATE STATISTICS" for this table?  Depending on the statistics in hand, it might think that the sequential scan might be quicker.</DIV> <BLOCKQUOTE style="MARGIN-RIGHT: 0px"> <DIV align=left class=OutlookMessageHeader dir=ltr>-----Original Message----- From: shahid.mehmood [mailto:shahid.mehmood@aku.edu] Sent: Monday, January 29, 2001 7:58 AM To: informix-list@iiug. org (E-mail) Cc: shahid.mehmood Subject: </DIV> OS: SCO UNIX 5.0, IX: OWS 7.20.UC2 I have a table named payprmbcalc which also has index on its three fields. This table contains 28000+ records. when I run a query on this table with the db engine searches the table using sequential scan, where as I am expecting search using an index. this query is taking too long to complete. can you guys suggest any thing how to improve this query ... The table schema and 'set explain on' output is attached here with. The Table Schema ... { TABLE "paydba".payprmbcalc row size = 58 number of columns = 9 index size = 36 } create table "paydba".payprmbcalc   (     paymonth integer not null constraint "paydba".n196_305,     internalno char(6) not null constraint "paydba".n196_306,     currency char(10) not null constraint "paydba".n196_307,     balance decimal(10,2),     product decimal(10,2),     taxprofit decimal(10,2),     ntaxprofit decimal(10,2),     lastedit date,     lastuser char(10)   ); create unique index "paydba".pp001idx on "paydba".payprmbcalc (paymonth,internalno, currency); the 'set explain output' ... QUERY: ------ select employee.employeeno , payprmbcalc.internalno,        employee.fname , employee.mname , employee.lname ,        payprmbcalc.currency , payprmbcalc.balance ,        employee.appointment , employee.termination ,        payprmbcalc.product , payprmbcalc.taxprofit ,        payprmbcalc.ntaxprofit   from payprmbcalc, employee  where payprmbcalc.paymonth = 2000130000    and employee.internalno  = payprmbcalc.internalno  order by 1 Estimated Cost: 7 Estimated # of Rows Returned: 5 Temporary Files Required For: Order By 1) paydba.payprmbcalc: SEQUENTIAL SCAN          { why ? i need index scan }     Filters: paydba.payprmbcalc.paymonth = 2000130000 2) paydba.employee: INDEX PATH     (1) Index Keys: internalno &

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