Re: Slow Query

Hi Venkata,

work_mem was set to 72MB, increased to 144MB, no change.

Added an index of type varchar_pattern_ops to Vacancy.JobTitle, this did
not help either.

On Wed, Aug 12, 2015 at 2:09 PM, Venkata Balaji N [via PostgreSQL] <
ml-node+s1045698n5861839h42(at)n5(dot)nabble(dot)com> wrote:

> On Wed, Aug 12, 2015 at 12:34 PM, robbyc <[hidden email]
> <http:///user/SendEmail.jtp?type=node&node=5861839&i=0>> wrote:
>
>> Hi,
>>
>> I am new to optimizing queries and i'm getting a slow running time
>> (~1.5secs) with the following SQL:
>>
>> SELECT distinct("Vacancy"."ID"), "Vacancy"."JobTitle",
>> "Vacancy"."DateCreated", "Vacancy"."CustomAccess"
>> , "Department"."Name" as "Department", list("Occupation"."Name") as
>> "Occupation", "Vacancy"."PositionNo"
>> , "Vacancy"."Template" from
>> "Vacancy"
>> LEFT JOIN "CategoryOption_TableRow" as "c_22"
>> ON ("c_22"."RowID" = "Vacancy"."ID"
>> and "c_22"."Category_TableID" = 22)
>> LEFT JOIN "CategoryOption" as "Occupation"
>> ON ("Occupation"."ID" = "c_22"."CategoryOptionID")
>> LEFT JOIN "TableRow_TableRow" as "t_33"
>> ON ("t_33"."Table1RowID" = "Vacancy"."ID"
>> and "t_33"."Table_TableID" = 33 )
>> LEFT JOIN "Department"
>> ON ("Department"."ID" = "t_33"."Table2RowID" and
>> "Department"."Active" = 't' and "Department"
>> ."ClientID" = 263)
>> JOIN "CategoryOption_TableRow" as "c_50" ON ("c_50"."Category_TableID"= 50
>> and "c_50"."RowID" = "Vacancy"
>> ."ID" and "c_50"."CategoryOptionID"=19205)
>> WHERE "Vacancy"."ClientID" = 263 AND "Vacancy"."ID" NOT IN(SELECT
>> DISTINCT("Vacancy"."ID")
>> FROM "Vacancy" join "CategoryOption_TableRow" "ct126" on
>> ("ct126"."Category_TableID" = 126
>> and "RowID" = "Vacancy"."ID")
>> left join "Workflow" on ("Workflow"."VacancyID" =
>> "Vacancy"."ID"
>> and "Workflow"."Level"
>> = 1)
>> left join "CategoryOption_TableRow" "c30" on ("c30"."RowID" =
>> "Workflow"."ID" and "c30"."Category_TableID"
>> = 30 and "c30"."CategoryOptionID" = 21923)
>> WHERE "Template" AND "ct126"."CategoryOptionID"
>> IN(34024,35254,35255,35256)) and "Vacancy"
>> ."Template" = 't'
>> GROUP BY "Vacancy"."ID", "Vacancy"."JobTitle", "Vacancy"."DateCreated",
>> "Vacancy"."CustomAccess", "Department"
>> ."Name", "Vacancy"."PositionNo", "Vacancy"."Template"
>> UNION
>> SELECT distinct("Vacancy"."ID"), "Vacancy"."JobTitle",
>> "Vacancy"."DateCreated", "Vacancy"."CustomAccess"
>> , "Department"."Name" as "Department", list("Occupation"."Name") as
>> "Occupation", "Vacancy"."PositionNo"
>> , "Vacancy"."Template" from
>> "Vacancy"
>> LEFT JOIN "CategoryOption_TableRow" as "c_22"
>> ON ("c_22"."RowID" = "Vacancy"."ID"
>> and "c_22"."Category_TableID" = 22)
>> LEFT JOIN "CategoryOption" as "Occupation"
>> ON ("Occupation"."ID" = "c_22"."CategoryOptionID")
>> LEFT JOIN "TableRow_TableRow" as "t_33"
>> ON ("t_33"."Table1RowID" = "Vacancy"."ID"
>> and "t_33"."Table_TableID" = 33 )
>> LEFT JOIN "Department"
>> ON ("Department"."ID" = "t_33"."Table2RowID" and
>> "Department"."Active" = 't' and "Department"
>> ."ClientID" = 263)
>> JOIN "CategoryOption_TableRow" as "c_50" ON ("c_50"."Category_TableID"= 50
>> and "c_50"."RowID" = "Vacancy"
>> ."ID" and "c_50"."CategoryOptionID"=19205)
>> WHERE "Vacancy"."ClientID" = 263 AND "Vacancy"."ID" NOT IN(SELECT
>> DISTINCT("Vacancy"."ID")
>> FROM "Vacancy" join "CategoryOption_TableRow" "ct126" on
>> ("ct126"."Category_TableID" = 126
>> and "RowID" = "Vacancy"."ID")
>> left join "Workflow" on ("Workflow"."VacancyID" =
>> "Vacancy"."ID"
>> and "Workflow"."Level"
>> = 1)
>> left join "CategoryOption_TableRow" "c30" on ("c30"."RowID" =
>> "Workflow"."ID" and "c30"."Category_TableID"
>> = 30 and "c30"."CategoryOptionID" = 21923)
>> WHERE "Template" AND "ct126"."CategoryOptionID"
>> IN(34024,35254,35255,35256)) and "Vacancy"
>> ."Template" <> 't' AND "Vacancy"."Level" = 1
>> GROUP BY "Vacancy"."ID", "Vacancy"."JobTitle", "Vacancy"."DateCreated",
>> "Vacancy"."CustomAccess", "Department"
>> ."Name", "Vacancy"."PositionNo", "Vacancy"."Template"
>> ORDER BY "JobTitle"
>>
>> Running explain analyze gives me the following information:
>> http://explain.depesz.com/s/pdC <http://explain.depesz.com/s/pdC>
>
>
>> For a total runtime: 2877.157 ms
>>
>> If i remove the left joins on Department and TableRow_TableRow this
>> reduces
>> the run time by about a third.
>> Additionally removing CategoryOption and CategoryOption_TableRow joins
>> further reduces by a about a third.
>>
>> Given that i need both these joins for the information retrieved by them,
>> what would be the best way to re-factor this query so it runs faster?
>>
>> Looking at the output of explain analyze the hash aggregates and sort seem
>> to be the primary issue.
>>
>
> The query has got a distinct and group-by/order-by clauses which seems to
> be taking time. Without looking at much details of the query code and Table
> size etc, did you try increasing the work_mem and then execute the query
> and see if that helps ? This will reduce the on-disk IO for sorting. Also,
> Vacancy.JobTitle seems to be a non-index column.
>
> Regards,
> Venkata Balaji
>
> Fujitsu Australia
>
>
>
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--
Regards

Robert Campbell
+61412062971
robcampbell73(at)gmail(dot)com

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