slow running query with a high lob logical reads, lob data

Last Post 01 Jun 2007 03:45 AM by teplitsa. 0 Replies.
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teplitsa
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01 Jun 2007 03:45 AM
we had some slow down complaints lately and this query seems to be the culprit almost every single time. The estimated execution plan is a clustered index seek as there is a clustered index on the uidcustomerid column. setting profile statistics on shows that every time it executes it does an index seek.

profiler session showed a huge number of reads for these queries depending on the value being looked up. 1500 through 50000. i set up profile io on and the culprit is lob logical reads. everything else is 0 or very low. in this case lob logical reads is over 1700.

3 of the columns in the select statement are text columns. when i take them out of the query the lob logical reads drops to 0 and goes up incrementally as i add each column back in.

is there anyway to improve the performance without changing data types to varchar(max)?


select SID,Last_name,Name_2,First_name,Middle_initial,Descriptives,Telephone_number,mainline,Residence,ADL,
DID_number,Svce_street,Svce_town,Svce_state,Svce_appt,Mailing_street,Mailing_town,Mailing_state,Mailing_appt,
Mailing_zip,Listing,Addl_listing,Published,Listed,Gold_number,PIN,status,SSnumber,tax_jurisdiction,
Bill_date,Past_balance,Service_start_date,Service_end_date,LOA,FCC_type,Line_type,I_W,Jacks,Voice_messaging,
vms_ring_cycles,CCS,phonesmarts,ringmate,voice_dialing,Bill_detail,Contact_Number,Contact_extension,
Best_Time,suspend,suspend_start,suspend_end,credits_allowed,credits_granted,home_region,Calling_Plan,Local_Plan,
Local_Plan_Rate,Flat_Rate,Sales_agent,Community,Building_Mgmt,How_Heard,Incentive_1,Incentive_1a,Incentive_1b,
Incentive_1c,Incentive_2,Incentive_2a,Incentive_2b,Incentive_2c,Incentive_3,Incentive_3a,Incentive_3b,
Incentive_3c,block_operator,block_collect,block_group,block_adult,block_call_return,block_repeat_dialing,
block_call_trace,block_caller_id,block_anonymous,block_all_high_toll,block_regional_and_ld,block_DA_Call_Completion,
block_DA,block_3rd_party,bank,prepayment,dial_around_number,custid,waive_interest,Financial_Treatment,
Other_Feature_1_code,Other_Feature_1_rate,Other_Feature_2_code,Other_Feature_2_rate,Other_Feature_3_code,
Other_Feature_3_rate,Other_Feature_4_code,Other_Feature_4_rate,Partial_Account,mail_date,snp_1_date,snp_2_date,
terminate_date,snp1notified,snp1peak,snp1offpeak,snp2notified,snp2peak,snp2offpeak,avg_days_paid,Pulled_Ld,SNP1,
SNP2,Treatment,Collections,Installment,Nynex_BTN,LD_rate,local_discount,to_month,rounds_up,full_package_made,
local_made,PIC,LPIC,tax_exempt_local,tax_exempt_federal,CommissionedAgent,LDRateID,UidCustomerId,
accVchLineClassUSOC,block_Inter_Reg_LD,block_international,block_DA_3rd_Collect,block_DH2,block_ISP_2,block_ISP_3,
block_ISP4_3_GBAS,block_ISP3_3_GBAS,block_collect_only,block_LD_Reg_DA,block_usage_based,block_ISP5_3_GBAS,
block_ISP5_2_GBAS,block_group_adult,csr_PIC,csr_LPIC,csr_SA,csr_exception,cutover_status,cutover_datetime,
OutsideAgent,prfVchAttributes,uidResellerID,Category,uidDealID
from profiles where UidCustomerID in (352199267)
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