c# - Improving SQLite index -

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i have sqlite database c# application i'm running in memory (:memory:). table has 650k rows, isn't much. want fast response-times on following query (syntax fetched linq sql dynamic linq query) 

select    sum([t0].[value1]) [sum],   [t0].[dim1] [primary],    [t0].[dim2] [secondary] [budgetline] [t0] [t0].[budgetid] = 4 group [t0].[dim1], [t0].[dim2]

which optimal index query? index other primary key looks following...

create index ix_0 on budgetline (budgetid, dim1, dim2) create index ix_1 on budgetline (budgetid) create index ix_2 on budgetline (dim1, dim2) create index ix_3 on budgetline (budgetid, dim1, dim2,value1)

currently execution times varies, around 1s current average. want query take less 0.5s @ least.

the table has 50 columns.

please assist

update: see 4 indexes above, these i'm getting 0.8s response...

remove indexes

create index ix_3 on budgetline (budgetid, dim1, dim2,value1) create index ix_0 on budgetline (budgetid, dim1, dim2)

and use budgetid index provided bartosz (but not dim1, dim2)

an in memory database going limited systems memory - running on underpowered or overtaxed machine? there reason why you're using :memory: instead of actual disk file? (see stack overflow question here)

also consider reading sqlite documentation performance tuning, sqlite performance windows

also try changing sql query follows:

    select     sum([value1]) [sum]     ,[dim1] [primary],      [dim2] [secondary] (     select        value1, dim1, dim2     [budgetline]     [budgetid] = 4 ) group [dim1], [dim2]

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