Re: [NOVICE] Bad Query?? Extremely slow response

Patrick,

This belongs on the SQL list, so I'm copying it there.

> HEELLLLPPPPPPP. I have this query which ran less than 20 seconds on
> my
> 500mhz MS SQL 2000 server with 192 megs ram. When I try to run this
> on my
> Postgres box which has dual 750mhz with 500 mg ram, it takes 3+ mins.
> If I
> run from PgAdminII, the app freezes. If I use a WHERE clause, data
> comes
> back extremely fast.
>
>
> SELECT c.itemnumber, c.mbmcolorcode, c.mbmsizedesc, c.mbmrange,
> c.upc,
> c.isavailable, c.totaloh, sum(c.mcoh) AS mcoh, c.backorder, c.oo,
> c.cost,
> c.retail, c.feddept, c.description, c.mbmdiv, c.mbmdept, c.mbmclass,
> sum
> (((c.mcoh + c.oo) - c.backorder)) AS totalavailable, c.pending_picks,
> c.pending_putaways, c.transfer_suspense, c.reserved, c.oo_lt_30_days,
> c.oo_30_60_days, c.oo_gt_60_days, c.last_receipt, sum((c.totaloh -
> (((c.pending_picks + c.transfer_suspense) + c.reserved) +
> c.backorder))) AS
> avail, s.pid
> FROM (cheshire_data c LEFT JOIN sku_non_inh s ON (((c.upc = s.upc)
> AND
> (c.itemnumber = s.itemnumber))))
> GROUP BY c.itemnumber, c.mbmcolorcode, c.mbmsizedesc, c.mbmrange,
> c.upc,
> c.cost, c.retail, c.feddept, c.description, c.mbmdiv, c.mbmdept,
> c.mbmclass, c.totaloh, c.backorder, c.oo, c.isavailable,
> c.pending_picks,
> c.pending_putaways, c.transfer_suspense, c.reserved, c.oo_lt_30_days,
> c.oo_30_60_days, c.oo_gt_60_days, c.last_receipt, s.pid;
>
> SCAN>>>
> Aggregate (cost=117164.97..130210.52 rows=18636 width=189)
> -> Group (cost=117164.97..128812.78 rows=186365 width=189)
> -> Sort (cost=117164.97..117164.97 rows=186365 width=189)
> -> Merge Join (cost=0.00..55710.79 rows=186365
> width=189)
> -> Index Scan using xie2cheshire_dataitem on
> cheshire_data c (cost=0.00..8003.01 rows=186365 width=161)
> -> Index Scan using xie2sku_non_inhitm on
> sku_non_inh
> s (cost=0.00..5774.53 rows=190048 width=28)

That's odd. You must be missing an index somewhere.
- Do you have indexes on itemnumber and upc on both tables? Are they
unique where applicable?
- You're showing a huge cost on aggregation. How many rows are in the
cheshire_data table?
- Your indication that the same query works fast with a where clause
may be a sign that you need to increase psotmaster's sort_mem
parameter.

-Josh

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