Wait # : nam'db file parallel read' ela 39297 files1 blocks7 requests7 obj#55745 tim.
Urgency_CD IS NOT null AND AT_ID 'Closed' 1 row selected.Insert into T, select TOP 810064 Getdate - 1, 4192, 'B '.As per the plan i was expecting db file sequential read but seeing db file scattered read was little shocking.Pre-fetch statistics) about wasted prefetched blocks.(Luckily this x tables columns are written in english not just abbreviations).There is an event 10299 which traces prefetch operations and if you set it to ckpt process youll see some aggregate statistics as well, also there arctic monkeys hotel casino vinyl area lot of prefetch statistics in vsesstat vsysstat On checking the session stat for prefetch 05:45:59 [email protected] select name.Wait # : nam'db file scattered read' ela 8081 file#60 block#71183 blocks8 obj#55745 tim.Update You can also read the below blog from Tanel Poder which mentions having mutliblock reads for index unique scan.Plan hash value:, id Operation Name Rows Bytes Cost (CPU) Time select statement (100) * 1 table access BY index rowid S_SEQ_CD 630K 54M 18774 (1) 00:03:46 * 2 index range scan S_SEQ_CD_M28_X 12M 552 (1) 00:00:, predicate Information (identified by operation id filter SC"."urgency_CD".
This is forever changing due to factors out of our control.
So, asynch IO should definitely be used when relying on index prefetch, otherwise your performance might degrade, especially when some of the prefetched blocks dont get used at all.
Update statisticith fullscan makes no difference.
Elapsed: 00:00:00.00 old 26: sql_id 1 new 26: sql_id 9kpjtkdz1mzus CH# parent_handle object_handle plan_hash OPT_cost parses H_parses executions fetches rows_processed CPU_MS priere chance jeux a gratter ELA_MS AVG_ELA lios pios sorts users_executing C76435E C7640D.43 1659.You have an index on startdate so it could start scanning that from the beginning, doing key lookups back to the base table and as soon as it finds the first matching row stop as it has found the MIN(startdate Similarly the MAX can.Where id between 801848 or id 810064.Urgency_CD IS NOT null AND AT_ID 'Closed'.We provide an always on scanner in the location of your choosing.Terms Of Service and have read our,.A.Qs, pokeFetch provides no guarantee on scan quality.Wait # : nam'db file scattered read' ela 9505 file#60 block#71169 blocks7 obj#55745 tim.Create table T ( id int identity(1,1) primary key, startdate datetime, fk int, status char(1 Filler char(2000) create nonclustered index ix ON T(startdate).Type_CD 'cmod' AND.Wait # : nam'db file sequential read' ela 14412 file#114 block#475510 blocks1 obj#531936 tim.The SQL Server cardinality estimator makes various modelling assumptions such.User xxxxxxxx db file scattered read 9kpjtkdz1mzus 0 0 waiting.Independence: Data distributions on different columns are independent unless correlation information is available.Wait # : nam'db file scattered read' ela 3226 file#60 block#71137 blocks8 obj#55745 tim.
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Ckpt process maintains statistics history in xkcbkpfs (kernel cache buffer k?
Giving 1,180 total lookups vs 1,893 so it chooses this plan.