In Top SQL Report. Why select sentence generate Direct Writes?

I don't understood, why select generates writes? 

SELECT T0.IBITM, T0.IBLITM, T0.IBAITM, T0.IBMCU, T0.IBSRP1, T0.IBSRP2, T0.IBSRP3, T0.IBSRP4, T0.IBSRP5, T0.IBSRP6, T0.IBSRP7, T0.IBSRP8, T0.IBSRP9, T0.IBSRP0, T0.IBPRP1, T0.IBPRP2, T0.IBPRP3, T0.IBPRP4, T0.IBPRP5, T0.IBPRP6, T0.IBPRP7, T0.IBPRP8, T0.IBPRP9, T0.IBPRP0, T0.IBCDCD, T0.IBPDGR, T0.IBDSGP, T0.IBVEND, T0.IBANPL, T0.IBBUYR, T0.IBGLPT, T0.IBORIG, T0.IBROPI, T0.IBROQI, T0.IBRQMX, T0.IBRQMN, T0.IBWOMO, T0.IBSERV, T0.IBSAFE, T0.IBSLD, T0.IBCKAV, T0.IBSRCE, T0.IBLOTS, T0.IBOT1Y, T0.IBOT2Y, T0.IBSTDP, T0.IBFRMP, T0.IBTHRP, T0.IBSTDG, T0.IBFRGD, T0.IBTHGD, T0.IBCOTY, T0.IBMMPC, T0.IBPRGR, T0.IBRPRC, T0.IBORPR, T0.IBBACK, T0.IBIFLA, T0.IBABCS, T0.IBABCM, T0.IBABCI, T0.IBOVR, T0.IBSHCM, T0.IBCARS, T0.IBCARP, T0.IBSHCN, T0.IBSTKT, T0.IBLNTY, T0.IBFIFO, T0.IBCYCL, T0.IBINMG, T0.IBWARR, T0.IBSRNR, T0.IBPCTM, T0.IBCMCG, T0.IBFUF1, T0.IBTX, T0.IBTAX1, T0.IBMPST, T0.IBMRPD, T0.IBMRPC, T0.IBUPC, T0.IBSNS, T0.IBMERL, T0.IBLTLV, T0.IBLTMF, T0.IBLTCM, T0.IBOPC, T0.IBOPV, T0.IBACQ, T0.IBMLQ, T0.IBLTPU, T0.IBMPSP, T0.IBMRPP, T0.IBITC, T0.IBECO, T0.IBECTY, T0.IBECOD, T0.IBMTF1, T0.IBMTF2, T0.IBMTF3, T0.IBMTF4, T0.IBMTF5, T0.IBMOVD, T0.IBQUED, T0.IBSETL, T0.IBSRNK, T0.IBSRKF, T0.IBTIMB, T0.IBBQTY, T0.IBORDW, T0.IBEXPD, T0.IBDEFD, T0.IBMULT, T0.IBSFLT, T0.IBMAKE, T0.IBLFDJ, T0.IBLLX, T0.IBCMGL, T0.IBURCD, T0.IBURDT, T0.IBURAT, T0.IBURAB, T0.IBURRF, T0.IBUSER, T0.IBPID, T0.IBJOBN, T0.IBUPMJ, T0.IBTDAY, T0.IBTFLA, T0.IBCOMH, T0.IBAVRT, T0.IBPOC, T0.IBAING, T0.IBBBDD, T0.IBCMDM, T0.IBLECM, T0.IBLEDD, T0.IBMLOT, T0.IBPEFD, T0.IBSBDD, T0.IBU1DD, T0.IBU2DD, T0.IBU3DD, T0.IBU4DD, T0.IBU5DD, T0.IBXDCK, T0.IBLAF, T0.IBLTFM, T0.IBRWLA, T0.IBLNPA, T0.IBLOTC, T0.IBAPSC, T0.IBPRI1, T0.IBPRI2, T0.IBLTCV, T0.IBASHL, T0.IBOPTH, T0.IBCUTH, T0.IBUMTH, T0.IBLMFG, T0.IBLINE, T0.IBDFTPCT, T0.IBKBIT, T0.IBDFENDITM, T0.IBKANEXLL, T0.IBSCPSELL, T1.IMITM, T1.IMLITM, T1.IMAITM, T1.IMDSC1, T1.IMDSC2, T1.IMSRTX, T1.IMALN, T1.IMSRP1, T1.IMSRP2, T1.IMSRP3, T1.IMSRP4, T1.IMSRP5, T1.IMSRP6, T1.IMSRP7, T1.IMSRP8, T1.IMSRP9, T1.IMSRP0, T1.IMPRP1, T1.IMPRP2, T1.IMPRP3, T1.IMPRP4, T1.IMPRP5, T1.IMPRP6, T1.IMPRP7, T1.IMPRP8, T1.IMPRP9, T1.IMPRP0, T1.IMCDCD, T1.IMPDGR, T1.IMDSGP, T1.IMPRGR, T1.IMRPRC, T1.IMORPR, T1.IMBUYR, T1.IMDRAW, T1.IMRVNO, T1.IMDSZE, T1.IMVCUD, T1.IMCARS, T1.IMCARP, T1.IMSHCN, T1.IMSHCM, T1.IMUOM1, T1.IMUOM2, T1.IMUOM3, T1.IMUOM4, T1.IMUOM6, T1.IMUOM8, T1.IMUOM9, T1.IMUWUM, T1.IMUVM1, T1.IMSUTM, T1.IMUMVW, T1.IMCYCL, T1.IMGLPT, T1.IMPLEV, T1.IMPPLV, T1.IMCLEV, T1.IMPRPO, T1.IMCKAV, T1.IMBPFG, T1.IMSRCE, T1.IMOT1Y, T1.IMOT2Y, T1.IMSTDP, T1.IMFRMP, T1.IMTHRP, T1.IMSTDG, T1.IMFRGD, T1.IMTHGD, T1.IMCOTY, T1.IMSTKT, T1.IMLNTY, T1.IMCONT, T1.IMBACK, T1.IMIFLA, T1.IMTFLA, T1.IMINMG, T1.IMABCS, T1.IMABCM, T1.IMABCI, T1.IMOVR, T1.IMWARR, T1.IMCMCG, T1.IMSRNR, T1.IMPMTH, T1.IMFIFO, T1.IMLOTS, T1.IMSLD, T1.IMANPL, T1.IMMPST, T1.IMPCTM, T1.IMMMPC, T1.IMPTSC, T1.IMSNS, T1.IMLTLV, T1.IMLTMF, T1.IMLTCM, T1.IMOPC, T1.IMOPV, T1.IMACQ, T1.IMMLQ, T1.IMLTPU, T1.IMMPSP, T1.IMMRPP, T1.IMITC, T1.IMORDW, T1.IMMTF1, T1.IMMTF2, T1.IMMTF3, T1.IMMTF4, T1.IMMTF5, T1.IMEXPD, T1.IMDEFD, T1.IMSFLT, T1.IMMAKE, T1.IMCOBY, T1.IMLLX, T1.IMCMGL, T1.IMCOMH, T1.IMURCD, T1.IMURDT, T1.IMURAT, T1.IMURAB, T1.IMURRF, T1.IMUSER, T1.IMPID, T1.IMJOBN, T1.IMUPMJ, T1.IMTDAY, T1.IMUPCN, T1.IMSCC0, T1.IMUMUP, T1.IMUMDF, T1.IMUMS0, T1.IMUMS1, T1.IMUMS2, T1.IMUMS3, T1.IMUMS4, T1.IMUMS5, T1.IMUMS6, T1.IMUMS7, T1.IMUMS8, T1.IMPOC, T1.IMAVRT, T1.IMEQTY, T1.IMWTRQ, T1.IMTMPL, T1.IMSEG1, T1.IMSEG2, T1.IMSEG3, T1.IMSEG4, T1.IMSEG5, T1.IMSEG6, T1.IMSEG7, T1.IMSEG8, T1.IMSEG9, T1.IMSEG0, T1.IMMIC, T1.IMAING, T1.IMBBDD, T1.IMCMDM, T1.IMLECM, T1.IMLEDD, T1.IMPEFD, T1.IMSBDD, T1.IMU1DD, T1.IMU2DD, T1.IMU3DD, T1.IMU4DD, T1.IMU5DD, T1.IMDLTL, T1.IMDPPO, T1.IMDUAL, T1.IMXDCK, T1.IMLAF, T1.IMLTFM, T1.IMRWLA, T1.IMLNPA, T1.IMLOTC, T1.IMAPSC, T1.IMAUOM, T1.IMCONB, T1.IMGCMP, T1.IMPRI1, T1.IMPRI2, T1.IMASHL, T1.IMVMINV, T1.IMCMETH, T1.IMEXPI, T1.IMOPTH, T1.IMCUTH, T1.IMUMTH, T1.IMLMFG, T1.IMLINE, T1.IMDFTPCT, T1.IMKBIT, T1.IMDFENDITM, T1.IMKANEXLL, T1.IMSCPSELL FROM PRODDTA.F4102 T0,PRODDTA.F4101 T1 WHERE  (  ( T1.IMTMPL NOT IN  ( :KEY1,:KEY2,:KEY3,:KEY4,:KEY5,:KEY6,:KEY7,:KEY8,:KEY9,:KEY10,:KEY11,:KEY12,:KEY13,:KEY14,:KEY15,:KEY16,:KEY17,:KEY18,:KEY19,:KEY20,:KEY21,:KEY22,:KEY23,:KEY24,:KEY25,:KEY26,:KEY27 )  AND T0.IBMCU NOT IN  ( :KEY28,:KEY29,:KEY30,:KEY31,:KEY32,:KEY33,:KEY34,:KEY35,:KEY36,:KEY37,:KEY38,:KEY39,:KEY40,:KEY41,:KEY42,:KEY43,:KEY44,:KEY45,:KEY46,:KEY47,:KEY48,:KEY49,:KEY50,:KEY51,:KEY52,:KEY53,:KEY54,:KEY55,:KEY56,:KEY57,:KEY58,:KEY59,:KEY60,:KEY61,:KEY62,:KEY63,:KEY64,:KEY65,:KEY66,:KEY67 )  )  )  AND  ( T1.IMITM=T0.IBITM )  ORDER BY T1.IMITM ASC

 

Why?

Thanks

  • How many rows are in the tables PRODDTA.F4102 and PRODDTA.F4101?
    Is there also update and/or insert activity on those tables?

    It's quite possible that if the rows were updated/created before the select, that the blocks are getting marked as 'dirty' and need to be flushed from the buffer cache, hence, DBWR will cause writes to do that.