Sqexplain info ????

Hi, In a VB program (using RDO) on NT Workstation 4.0 SP3, running OLWS 7.22, I have the following SQ Lstatement : select * from tad where thr_id = ? and tad_order = 1 AND trl_id IS NULL I generated a sqexplain.out file to check this query, and the sqexplain.out file contains 3 different queries. SELECT * FROM tad WHERE thr_id = ? AND tad_order = 1 AND trl_id IS NULLEstimated Cost: 2 Estimated # of Rows Returned: 1 1) informix.tad: INDEX PATH Filters: informix.tad.tad_order = 1 (1) Index Keys: thr_id trl_id Lower Index Filter: (informix.tad.thr_id = 359 AND informix.tad.trl_id IS NULL ) SELECT * FROM tadEstimated Cost: 3 Estimated # of Rows Returned: 10 1) informix.tad: SEQUENTIAL SCAN select con.owner,tabname,colname,colno,constrname, part1, part2, part3, part4, part5, part6, part7, part8, part9, part10, part11, part12, part13, part14, part15, part16 FROM informix.systables t, informix.syscolumns c,informix.sysindexes i, informix.sysconstraints con WHERE t.tabid = i.tabid AND t.tabid = con.tabid AND t.tabid = c.tabid AND constrtype = 'P' AND con.idxname = i.idxname AND con.owner = i.owner AND (colno = part1 OR colno = part2 OR colno = part3 OR colno = part4 OR colno = part5 OR colno = part6 OR colno = part7 OR colno = part8 OR colno = part9 OR colno = part10 OR colno = part11 OR colno = part12 OR colno = part13 OR colno = part14 OR colno = part15 OR colno = part16) AND t.tabname = 'tad' Estimated Cost: 9 Estimated # of Rows Returned: 1 1) pfornaci.con: SEQUENTIAL SCAN Filters: pfornaci.con.constrtype = 'P' 2) pfornaci.t: INDEX PATH Filters: pfornaci.t.tabname = 'tad' (1) Index Keys: tabid Lower Index Filter: pfornaci.t.tabid = pfornaci.con.tabid 3) pfornaci.i: INDEX PATH (1) Index Keys: idxname owner tabid Lower Index Filter: (pfornaci.i.idxname = pfornaci.con.idxname AND (pfornaci.i.owner = pfornaci.con.owner AND pfornaci.i.tabid = pfornaci.con.tabid ) ) 4) pfornaci.c: INDEX PATH Filters: (((((((((((((((pfornaci.c.colno = pfornaci.i.part1 OR pfornaci.c.colno = pfornaci.i.part2 ) OR pfornaci.c.colno = pfornaci.i.part3 ) OR pfornaci.c.colno = pfornaci.i.part4 ) OR pfornaci.c.colno = pfornaci.i.part5 ) OR pfornaci.c.colno = pfornaci.i.part6 ) OR pfornaci.c.colno = pfornaci.i.part7 ) OR pfornaci.c.colno = pfornaci.i.part8 ) OR pfornaci.c.colno = pfornaci.i.part9 ) OR pfornaci.c.colno = pfornaci.i.part10 ) OR pfornaci.c.colno = pfornaci.i.part11 ) OR pfornaci.c.colno = pfornaci.i.part12 ) OR pfornaci.c.colno = pfornaci.i.part13 ) OR pfornaci.c.colno = pfornaci.i.part14 ) OR pfornaci.c.colno = pfornaci.i.part15 ) OR pfornaci.c.colno = pfornaci.i.part16 ) (1) Index Keys: tabid colno Lower Index Filter: pfornaci.c.tabid = pfornaci.con.tabid What is the reason ? Seems like the cost of the 2nd and 3rd query is not really null.... Any ideas ? Thank you Philippe Fornaciari Summit Technologies International p.fornaciari@summittechnologies.com