Re: Regarding query execution for long time

On 1/28/19 8:10 AM, Durgamahesh Manne wrote:
>
>
> On Mon, Jan 28, 2019 at 6:34 PM Ron <ronljohnsonjr(at)gmail(dot)com
> <mailto:ronljohnsonjr(at)gmail(dot)com>> wrote:
>
> On 1/28/19 6:20 AM, Durgamahesh Manne wrote:
> > Hi
> >
> > below query is being executed for long time
> >
> > Select
> > distinct ltrim(rtrim(ssnumber)), CL.iInsightClientId,
> > ltrim(rtrim(TFA.client_account_key)) as vchAccountNumber,
> > concat(TFA.first_name, ' ', TFA.last_name) as vchAccountName,
> > concat('AP:TIAA', TFA.routing_number) as vchRepLabel,
> > null as vchOpenDate, TFA.address1 as vchAccountTiteLine2,
> > TFA.address2 as vchAccountTitleLine3,null as vchAccountType,
> > TFA.address1 as vchPrimaryContact, 'TIAA-CREF' as Custodian,
> > TFA.routing_number as vchCustodian_RepId, null as vchCustodianRepName,
> > CONCAT ('TIAA-CREF:',ltrim(rtrim(client_account_key)),':',
> > ltrim(rtrim(ssnumber))) as vchAccountKey,
> > null as vchFeedsAccountType
> > from accounts as TFA
> > join client3 as CL on
> ltrim(rtrim(Cl.vchssnumber))=ltrim(rtrim(TFA.ssnumber))
> > left join account3 as AC on
> >
> ltrim(rtrim(AC."vchCustodianAccountNumber"))=ltrim(rtrim(TFA.client_account_key))
> > where AC."iInsightAccountID" is null;
> >
> >  query is being executed for long time even after i have created
> required
> > indexes on columns of the tables
> > please help for fast query execution
>
> I bet this is what's causing your troubles:
> on ltrim(rtrim(Cl.vchssnumber))=ltrim(rtrim(TFA.ssnumber))
>
> The query optimizer probably can't use indexes on those tables.
>

> Hi
>   why query optimizer can't use indexes on those columns of the tables

Because of the ltrim() functions.  B-trees sort the data on the field
values, and ltrim() changes that.
For example, these two strings are different, and therefore the b-tree puts
them in different places in the tree.
  snagglefrob
snagglefrob

Using lrtrim() makes them logically eqivalent, but not physically equivalent.

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