Update Statistics

For the following table on IDS versions 9.30xC2 and up create table t ( a integer, b integer, c integer, d integer, e integer ) create unique index idx1 on t (a, b); create index idx2 on t (b, c, d); create index idx3 on t (b, c, e); do update statistics low for table t (a, b); update statistics low for table t (b, c, d); update statistics low for table t (b, c, e); have the same net effect as update statistics low for table t (a, b, c, d, e); ? and do update statistics medium for table t distributions only; update statistics high for table t (a) distributions only; update statistics high for table t (b) distributions only; update statistics high for table t (d) distributions only; update statistics high for table t (e) distributions only; have the same net effect as update statistics medium for table t (c) distributions only; update statistics high for table t (a, b, d, e) distributions only; ? Sorry if this has been answered before. Tried the following but no definitive answer was found. http://www3.software.ibm.com/ibmdl/pub/software/dw/dm/informix/0211desai/0211desai.pdf (understand the optimizer) http://www-128.ibm.com/developerworks/db2/zones/informix/library/techarticle/miller/0203miller.html (tuning update statistics) http://publibfp.boulder.ibm.com/epubs/pdf/8344.pdf (9.3 performance tuning guide) http://groups-beta.google.com/group/comp.databases.informix/browse_frm/thread/a852f14f35a0038d/6a2d537ae8d21b02?q=update+statistics+repeated+column&rnum=1&hl=en#6a2d537ae8d21b02 (cdi post, but based on 7.21 recommendations) Also, anyone aware of SET EXPLAIN ON in 9.30.UC2 for update statistics only writing out 1 char to the sqexplain.out file? Thanks, Andrew sending to informix-list