Performance Problem with postgresql 9.03, 8GB RAM, Quadcore Processor Server--Need help!!!!!!!

what sort of queries you are running against it ? the select * from..
is not really (hopefully) a query you are running from your php app.

Actually we are using various views and functions to get the info for
reporting purpose in that views or functions we have used or joined the
above table mentioned.

I thought of will get reply from any one from the lists so only i put anyway
i will continue with only pgsql-performance mailing lists.

Regards
Hashim

On Fri, Oct 28, 2011 at 1:28 PM, Gregg Jaskiewicz <gryzman@gmail.com> wrote:

what sort of queries you are running against it ? the select * from..
is not really (hopefully) a query you are running from your php app.

--
Regards
Mohamed Hashim.N
Mobile:09894587678

On 28 October 2011 09:02, Mohamed Hashim <nmdhashim@gmail.com> wrote:

EXPLAIN select * from stk_source ;
                                     QUERY
PLAN
-------------------------------------------------------------------------------------
 Result  (cost=0.00..6575755.39 rows=163132513 width=42)
   ->  Append  (cost=0.00..6575755.39 rows=163132513 width=42)
         ->  Seq Scan on stk_source  (cost=0.00..42.40 rows=1080 width=45)
         ->  Seq Scan on stk_source  (cost=0.00..20928.37 rows=519179
width=42)
         ->  Seq Scan on stk_source  (cost=0.00..85125.82 rows=2111794
width=42)
         ->  Seq Scan on stk_source  (cost=0.00..6469658.80 rows=160500460
width=42)

That plan gives you the best possible performance given your query.
Your example probably doesn't fit the problem you're investigating.

--
If you can't see the forest for the trees,
Cut the trees and you'll see there is no forest.

On 28 October 2011 13:37, Alban Hertroys <haramrae@gmail.com> wrote:

On 28 October 2011 09:02, Mohamed Hashim <nmdhashim@gmail.com> wrote:

Please don't cross-post to mailing lists for multiple projects.

--
If you can't see the forest for the trees,
Cut the trees and you'll see there is no forest.

Thanks Alban & Gregg.

i will describe little more about that table

- We are using PHP application with Apache server & Postgresql 9.0.3 in a
dedicated server.
- stk_source table is mainly used to track the transactions from parent
to child

Table "_100410.stk_source"
Column | Type |
Modifiers
-----------------------+-----------+-----------------------------------------------------
source_id | integer | not null default
nextval('source_id_seq'::regclass)
stock_id | integer |
source_detail | integer[] |
transaction_reference | integer |
is_user_set | boolean | default false

We store transaction_type and transaction_id in source_detail column which
is an interger array for each transactions

We use various functions to get the info based on transaction type

For eg:

In function to get the batch details we have used as

FOR batch_id_rec in select distinct(batch_id) from order_status_batches osb
join batch_status_stock bss on osb.status_id=bss.batch_status_id where
stock_id in (select source_detail[2] from stk_source where stock_id IN
(SELECT
std_i.stock_id

FROM order_details_shipments
ods

JOIN shipment_pack_stock sps ON sps.pack_id=ods.pack_id AND
ods.order_id=sps.order_id AND ods.item_id=sps.item_id
JOIN stock_transaction_detail_106 std ON
std.transaction_id=sps.transaction_id
JOIN stock_transaction_detail_106 std_i ON std.stock_id =
std_i.stock_id AND std_i.transaction_type = 'i'::bpchar
WHERE shipment_item_id=$1 ) and source_detail[1]=3) LOOP

...............................

................................

......................................

Similarly we have used in php pages and views

SELECT abd.bill_no as bill_no,to_char(abd.bill_date,'dd/mm/yyyy') AS
date,mp.product_desc as product_desc,std.quantity,std.area,rip.price AS
rate,
FROM acc_bill_items_106 abi
JOIN acc_bill_details_106_table abd ON abd.bill_id=abi.bill_id AND
abd.bill_status='act'
JOIN stk_source_table ss ON ss.source_detail[2]=abi.item_id and
ss.source_detail[1]=1
JOIN stock_transaction_detail_106_table std ON std.stock_id=ss.stock_id
JOIN stock_details_106_table sd106 ON sd106.stock_id=std.stock_id
JOIN master_product_106_table mp ON mp.product_id= sd106.product_id
JOIN receipt_item_price_106_table rip ON rip.receipt_item_id=abi.item_id
WHERE abi.bill_id=$bill_id AND std.transaction_type='o' ;

So where ever we have JOIN or used in functions the performance is very low
some times query returns results takes more than 45 mints.

Normally if we fetch Select * from some_table..........it returns very fast
because it has less records.

But when i put Select * from stk_source or to find the actual_cost

EXPLAIN ANALYZE SELECT * FROM stk_source;

i couln't able to retrieve the planner details waited for more than 50 to 60
mints

so question is in spite of having good server with high configuration and
also changed the postgresql configuration settings then why the system is
crawling?

*What are the other parameters have to look out or what are the other config
settings to be change to have the best performance??*

Kindly help to sort out this problem......

Thanks in advance..................!!!!!!

Regards
Hashim

On Fri, Oct 28, 2011 at 5:07 PM, Alban Hertroys <haramrae@gmail.com> wrote:

On 28 October 2011 09:02, Mohamed Hashim <nmdhashim@gmail.com> wrote:

EXPLAIN select * from stk_source ;
QUERY
PLAN

-------------------------------------------------------------------------------------

Result (cost=0.00..6575755.39 rows=163132513 width=42)
-> Append (cost=0.00..6575755.39 rows=163132513 width=42)
-> Seq Scan on stk_source (cost=0.00..42.40 rows=1080

width=45)

-> Seq Scan on stk_source (cost=0.00..20928.37 rows=519179
width=42)
-> Seq Scan on stk_source (cost=0.00..85125.82 rows=2111794
width=42)
-> Seq Scan on stk_source (cost=0.00..6469658.80

rows=160500460

width=42)

That plan gives you the best possible performance given your query.
Your example probably doesn't fit the problem you're investigating.

--
If you can't see the forest for the trees,
Cut the trees and you'll see there is no forest.

--
Regards
Mohamed Hashim.N
Mobile:09894587678

Any idea or suggestions how to improve my database best
performance.................???

Regards
Hashim

On Sat, Oct 29, 2011 at 9:40 AM, Mohamed Hashim <nmdhashim@gmail.com> wrote:

Thanks Alban & Gregg.

i will describe little more about that table

- We are using PHP application with Apache server & Postgresql 9.0.3
in a dedicated server.
- stk_source table is mainly used to track the transactions from
parent to child

Table "_100410.stk_source"
Column | Type |
Modifiers
-----------------------+-----------+-----------------------------------------------------

source_id | integer | not null default
nextval('source_id_seq'::regclass)
stock_id | integer |
source_detail | integer[] |
transaction_reference | integer |
is_user_set | boolean | default false

We store transaction_type and transaction_id in source_detail column which
is an interger array for each transactions

We use various functions to get the info based on transaction type

For eg:

In function to get the batch details we have used as

FOR batch_id_rec in select distinct(batch_id) from order_status_batches
osb join batch_status_stock bss on osb.status_id=bss.batch_status_id where
stock_id in (select source_detail[2] from stk_source where stock_id IN
(SELECT
std_i.stock_id

FROM order_details_shipments
ods

JOIN shipment_pack_stock sps ON sps.pack_id=ods.pack_id AND
ods.order_id=sps.order_id AND ods.item_id=sps.item_id
JOIN stock_transaction_detail_106 std ON
std.transaction_id=sps.transaction_id
JOIN stock_transaction_detail_106 std_i ON std.stock_id =
std_i.stock_id AND std_i.transaction_type = 'i'::bpchar
WHERE shipment_item_id=$1 ) and source_detail[1]=3) LOOP

...............................

................................

......................................

Similarly we have used in php pages and views

SELECT abd.bill_no as bill_no,to_char(abd.bill_date,'dd/mm/yyyy') AS
date,mp.product_desc as product_desc,std.quantity,std.area,rip.price AS
rate,
FROM acc_bill_items_106 abi
JOIN acc_bill_details_106_table abd ON abd.bill_id=abi.bill_id AND
abd.bill_status='act'
JOIN stk_source_table ss ON ss.source_detail[2]=abi.item_id and
ss.source_detail[1]=1
JOIN stock_transaction_detail_106_table std ON std.stock_id=ss.stock_id
JOIN stock_details_106_table sd106 ON sd106.stock_id=std.stock_id
JOIN master_product_106_table mp ON mp.product_id= sd106.product_id
JOIN receipt_item_price_106_table rip ON
rip.receipt_item_id=abi.item_id
WHERE abi.bill_id=$bill_id AND std.transaction_type='o' ;

So where ever we have JOIN or used in functions the performance is very
low some times query returns results takes more than 45 mints.

Normally if we fetch Select * from some_table..........it returns very
fast because it has less records.

But when i put Select * from stk_source or to find the actual_cost

EXPLAIN ANALYZE SELECT * FROM stk_source;

i couln't able to retrieve the planner details waited for more than 50 to
60 mints

so question is in spite of having good server with high configuration and
also changed the postgresql configuration settings then why the system is
crawling?

*What are the other parameters have to look out or what are the other
config settings to be change to have the best performance??*

Kindly help to sort out this problem......

Thanks in advance..................!!!!!!

Regards
Hashim

On Fri, Oct 28, 2011 at 5:07 PM, Alban Hertroys <haramrae@gmail.com>wrote:

On 28 October 2011 09:02, Mohamed Hashim <nmdhashim@gmail.com> wrote:

EXPLAIN select * from stk_source ;
QUERY
PLAN

-------------------------------------------------------------------------------------

Result (cost=0.00..6575755.39 rows=163132513 width=42)
-> Append (cost=0.00..6575755.39 rows=163132513 width=42)
-> Seq Scan on stk_source (cost=0.00..42.40 rows=1080

width=45)

-> Seq Scan on stk_source (cost=0.00..20928.37 rows=519179
width=42)
-> Seq Scan on stk_source (cost=0.00..85125.82 rows=2111794
width=42)
-> Seq Scan on stk_source (cost=0.00..6469658.80

rows=160500460

width=42)

That plan gives you the best possible performance given your query.
Your example probably doesn't fit the problem you're investigating.

--
If you can't see the forest for the trees,
Cut the trees and you'll see there is no forest.

--
Regards
Mohamed Hashim.N
Mobile:09894587678

--
Regards
Mohamed Hashim.N
Mobile:09894587678

Hi Hashim,

After I upgraded from Postgres 8.3/8.4 to 9.0 I had all sorts of
problems with queries with many joins. Queries that used to take 1ms
suddenly take half a minute for no apparent reason.

I have 72GB which I think makes the planner go bonkers and be too eager
doing a seq scan. I tried to compensate with ridiculously low
cpu_index_tuple_cost but it had little effect.

If I were you, I would try to remove some of the joined tables and see
what happens. When does it start to run very slowly? How does the plan
look right before it's super slow?

One workaround I've done is if something looking like this....

select
...
from
table_linking_massive_table tlmt
,massive_table mt
,some_table1 st1
,some_table2 st2
,some_table3 st3
,some_table4 st4
where
tlmt.group_id = 123223 AND
mt.id = tmlt.massive_table AND
st1.massive_table = mt.id AND
st2.massive_table = mt.id AND
st3.massive_table = mt.id AND
st4.massive_table = mt.id

...suddenly gets slow, it has helped to rewrite it as....

select
...
from
(
select
...
from
table_linking_massive_table tlmt
,massive_table mt
where
tlmt.group_id = 123223 AND
mt.id = tmlt.massive_table AND
) as mt
,some_table1 st1
,some_table2 st2
,some_table3 st3
,some_table4 st4
where
tlmt.group_id = 123223 AND
mt.id = tmlt.massive_table AND
st1.massive_table = mt.id AND
st2.massive_table = mt.id AND
st3.massive_table = mt.id AND
st4.massive_table = mt.id

This seems to force Postgres to evaluate the mt subselect first and not
get ideas about how to join. It was a few years ago since I used Oracle
but if I remember correctly Oracle looked at the order of the things in
the where section. In this example Oracle would be encourage to use tlmt
as base table and take it from there. It doesn't seem to me that
Postgres cares about this order. Not caring would possibly be more
forgiving with automatically generated sql but it also implies the
planner always makes the best decisions which it obviously is not. I
might be talking rubbish here, these are my empirical observations.

I'm sure you'll get better answers, but this is what I've done.

I assume you have done your analyze & indexing correctly etc.

Best regards,
Marcus

On Tue, Nov 01, 2011 at 08:33:51AM +0530, Mohamed Hashim wrote:

Any idea or suggestions how to improve my database best
performance.................???

Regards
Hashim

Hi Hashim,

Ignoring the description of your tables, you should probably try
updating to the latest release 9.0.5. You are two point releases
back and they really, really, really fix bugs in each release or
they do not bother releasing.

Regards,
Ken

On 1 Listopad 2011, 10:57, Marcus Engene wrote:

Hi Hashim,

One workaround I've done is if something looking like this....

select
...
from
table_linking_massive_table tlmt
,massive_table mt
,some_table1 st1
,some_table2 st2
,some_table3 st3
,some_table4 st4
where
tlmt.group_id = 123223 AND
mt.id = tmlt.massive_table AND
st1.massive_table = mt.id AND
st2.massive_table = mt.id AND
st3.massive_table = mt.id AND
st4.massive_table = mt.id

...suddenly gets slow, it has helped to rewrite it as....

select
...
from
(
select
...
from
table_linking_massive_table tlmt
,massive_table mt
where
tlmt.group_id = 123223 AND
mt.id = tmlt.massive_table AND
) as mt
,some_table1 st1
,some_table2 st2
,some_table3 st3
,some_table4 st4
where
tlmt.group_id = 123223 AND
mt.id = tmlt.massive_table AND
st1.massive_table = mt.id AND
st2.massive_table = mt.id AND
st3.massive_table = mt.id AND
st4.massive_table = mt.id

Can you please post EXPLAIN ANALYZE of those queries? It's difficult to
see what's wrong when we don't know the plan (and the actual stats
gathered during execution). Use explain.depesz.com to post the output.

Tomas

Marcus Engene <mengpg2@engene.se> writes:

After I upgraded from Postgres 8.3/8.4 to 9.0 I had all sorts of
problems with queries with many joins. Queries that used to take 1ms
suddenly take half a minute for no apparent reason.

Could we see a concrete test case, rather than hand waving? If there's
really a problem in 9.0, it's impossible to fix it on so little detail.

One workaround I've done is if something looking like this....

The only way that should make a difference is if the total number
of tables in the query exceeds from_collapse_limit (or maybe
join_collapse_limit, depending on exactly how you wrote the query).
Perhaps you'd been running with nonstandard values of those settings
in 8.x, and forgot to transfer them into the new DB?

regards, tom lane

Dear All

Thanks for your suggestions & replies.

The below are the sample query which i put for particular one bill_id

EXPLAIN ANALYZE SELECT abd.bill_no as
bill_no,to_char(abd.bill_date,'dd/mm/yyyy') AS date,mp.product_desc as
product_desc,std.quantity,std.area,rip.price AS rate
FROM acc_bill_items_106 abi
JOIN acc_bill_details_106 abd ON abd.bill_id=abi.bill_id
JOIN stk_source ss ON ss.source_detail[1]=1 and
ss.source_detail[2]=abi.item_id
JOIN stock_transaction_detail_106 std ON std.stock_id=ss.stock_id
JOIN stock_details_106 sd106 ON sd106.stock_id=std.stock_id
JOIN master_product_106 mp ON mp.product_id= sd106.product_id
JOIN receipt_item_price_106 rip ON rip.receipt_item_id=abi.item_id
WHERE abi.bill_id=12680;

QUERY
PLAN

-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Nested Loop (cost=0.00..7230339.59 rows=54369 width=39) (actual
time=158156.895..158157.206 rows=1 loops=1)
-> Nested Loop (cost=0.00..7149579.10 rows=8192 width=32) (actual
time=158156.863..158157.172 rows=1 loops=1)
-> Nested Loop (cost=0.00..7119922.60 rows=8192 width=27)
(actual time=158156.855..158157.164 rows=1 loops=1)
-> Nested Loop (cost=0.00..7086865.70 rows=8192 width=19)
(actual time=158156.835..158157.143 rows=1 loops=1)
Join Filter: (abi.item_id = ss.source_detail[2])
-> Nested Loop (cost=0.00..604.54 rows=2 width=23)
(actual time=2.782..2.786 rows=1 loops=1)
-> Index Scan using acc_bill_details_106_pkey
on acc_bill_details_106 abd (cost=0.00..6.29 rows=1 width=12) (actual
time=0.010..0.012 rows=1 loops=1)
Index Cond: (bill_id = 12680)
-> Nested Loop (cost=0.00..598.19 rows=2
width=19) (actual time=2.770..2.772 rows=1 loops=1)
Join Filter: (abi.item_id =
rip.receipt_item_id)
-> Seq Scan on receipt_item_price_106
rip (cost=0.00..162.48 rows=4216 width=11) (actual time=0.005..0.562
rows=4218 loops=1)
-> Materialize (cost=0.00..140.59 rows=2
width=8) (actual time=0.000..0.000 rows=1 loops=4218)
-> Seq Scan on acc_bill_items_106
abi (cost=0.00..140.58 rows=2 width=8) (actual time=0.412..0.412 rows=1
loops=1)
Filter: (bill_id = 12680)
-> Materialize (cost=0.00..7024562.68 rows=819222
width=33) (actual time=0.035..153869.575 rows=19010943 loops=1)
-> Append (cost=0.00..7014065.57 rows=819222
width=33) (actual time=0.034..145403.828 rows=19010943 loops=1)
-> Seq Scan on stk_source ss
(cost=0.00..45.10 rows=5 width=36) (actual time=0.001..0.001 rows=0 loops=1)
Filter: (source_detail[1] = 1)
-> Seq Scan on stk_source ss
(cost=0.00..22226.32 rows=2596 width=33) (actual time=0.033..118.019
rows=66356 loops=1)
Filter: (source_detail[1] = 1)
-> Seq Scan on stk_source ss
(cost=0.00..90405.31 rows=10559 width=33) (actual time=0.010..490.712
rows=288779 loops=1)
Filter: (source_detail[1] = 1)
-> Seq Scan on stk_source ss
(cost=0.00..6901388.84 rows=806062 width=33) (actual
time=13.382..142493.302 rows=18655808 loops=1)
Filter: (source_detail[1] = 1)
-> Index Scan using sd106_stock_id_idx on stock_details_106
sd106 (cost=0.00..4.00 rows=1 width=8) (actual time=0.014..0.014 rows=1
loops=1)
Index Cond: (sd106.stock_id = ss.stock_id)
-> Index Scan using master_product_pkey on master_product_106 mp
(cost=0.00..3.59 rows=1 width=13) (actual time=0.006..0.006 rows=1 loops=1)
Index Cond: (mp.product_id = sd106.product_id)
-> Index Scan using std106_stock_id_idx on stock_transaction_detail_106
std (cost=0.00..9.70 rows=4 width=19) (actual time=0.007..0.009 rows=1
loops=1)
Index Cond: (std.stock_id = ss.stock_id)
Total runtime: 158240.795 ms

<http://goog_1591150719&gt;*http://explain.depesz.com/s/Tyc

*Similarly i have used the queries on various details pages and views that
too if i go for one month transactions its taking so much times.

I will try to upgrade to latest version and will try to tune more my
queries so changing the conf settings wouldn't help for better performance??

Thanks & Regards
Hashim

On Tue, Nov 1, 2011 at 7:13 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:

Marcus Engene <mengpg2@engene.se> writes:

After I upgraded from Postgres 8.3/8.4 to 9.0 I had all sorts of
problems with queries with many joins. Queries that used to take 1ms
suddenly take half a minute for no apparent reason.

Could we see a concrete test case, rather than hand waving? If there's
really a problem in 9.0, it's impossible to fix it on so little detail.

One workaround I've done is if something looking like this....

The only way that should make a difference is if the total number
of tables in the query exceeds from_collapse_limit (or maybe
join_collapse_limit, depending on exactly how you wrote the query).
Perhaps you'd been running with nonstandard values of those settings
in 8.x, and forgot to transfer them into the new DB?

regards, tom lane

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--
Regards
Mohamed Hashim.N
Mobile:09894587678

Mohamed Hashim <nmdhashim@gmail.com> writes:

The below are the sample query which i put for particular one bill_id

EXPLAIN ANALYZE SELECT abd.bill_no as
bill_no,to_char(abd.bill_date,'dd/mm/yyyy') AS date,mp.product_desc as
product_desc,std.quantity,std.area,rip.price AS rate
FROM acc_bill_items_106 abi
JOIN acc_bill_details_106 abd ON abd.bill_id=abi.bill_id
JOIN stk_source ss ON ss.source_detail[1]=1 and
ss.source_detail[2]=abi.item_id
JOIN stock_transaction_detail_106 std ON std.stock_id=ss.stock_id
JOIN stock_details_106 sd106 ON sd106.stock_id=std.stock_id
JOIN master_product_106 mp ON mp.product_id= sd106.product_id
JOIN receipt_item_price_106 rip ON rip.receipt_item_id=abi.item_id
WHERE abi.bill_id=12680;

All the time seems to be going into the seqscan on stk_source and its
child tables. It looks like it would help if "ss.source_detail[1]=1 and
ss.source_detail[2]=abi.item_id" were indexable (particularly the
latter). Which probably means you need to rethink your data
representation. Putting things that you need to index on into an array
is not a very good design. I suppose you can do it if you're absolutely
set on it (functional indexes on (source_detail[1]) and (source_detail[2]))
but it appears to suck from a notational point of view too. Six months
from now, when you look at this code, are you going to remember what's
the difference between source_detail[1] and source_detail[2]? Not
without consulting your notes, I bet.

regards, tom lane

Am 02.11.2011 08:12, schrieb Mohamed Hashim:

Dear All

Thanks for your suggestions & replies.

The below are the sample query which i put for particular one bill_id

EXPLAIN ANALYZE SELECT abd.bill_no as
bill_no,to_char(abd.bill_date,'dd/mm/yyyy') AS date,mp.product_desc as
product_desc,std.quantity,std.area,rip.price AS rate
FROM acc_bill_items_106 abi
JOIN acc_bill_details_106 abd ON abd.bill_id=abi.bill_id
JOIN stk_source ss ON ss.source_detail[1]=1 and
ss.source_detail[2]=abi.item_id
JOIN stock_transaction_detail_106 std ON std.stock_id=ss.stock_id
JOIN stock_details_106 sd106 ON sd106.stock_id=std.stock_id
JOIN master_product_106 mp ON mp.product_id= sd106.product_id
JOIN receipt_item_price_106 rip ON rip.receipt_item_id=abi.item_id
WHERE abi.bill_id=12680;

First I would try this:
explain analyze select * from stk_source where source_detail[1] = 1;
explain analyze select * from stk_source where source_detail[2] = 12356;

Both times you'll get sequential scans, and that's the root of the
problem. Oh, you mentioned that you use partitioning, but there seems to
be no condition for that.

You should really rethink your database schema, at least try to pull out
all indexable fields out of that int[] into columns, and use indices on
those fields.

Regards
Mario

On 3 Listopad 2011, 16:02, Mario Weilguni wrote:

Am 02.11.2011 08:12, schrieb Mohamed Hashim:

Dear All

Thanks for your suggestions & replies.

The below are the sample query which i put for particular one bill_id

EXPLAIN ANALYZE SELECT abd.bill_no as
bill_no,to_char(abd.bill_date,'dd/mm/yyyy') AS date,mp.product_desc as
product_desc,std.quantity,std.area,rip.price AS rate
FROM acc_bill_items_106 abi
JOIN acc_bill_details_106 abd ON abd.bill_id=abi.bill_id
JOIN stk_source ss ON ss.source_detail[1]=1 and
ss.source_detail[2]=abi.item_id
JOIN stock_transaction_detail_106 std ON std.stock_id=ss.stock_id
JOIN stock_details_106 sd106 ON sd106.stock_id=std.stock_id
JOIN master_product_106 mp ON mp.product_id= sd106.product_id
JOIN receipt_item_price_106 rip ON rip.receipt_item_id=abi.item_id
WHERE abi.bill_id=12680;

First I would try this:
explain analyze select * from stk_source where source_detail[1] = 1;
explain analyze select * from stk_source where source_detail[2] = 12356;

Both times you'll get sequential scans, and that's the root of the
problem. Oh, you mentioned that you use partitioning, but there seems to
be no condition for that.

You should really rethink your database schema, at least try to pull out
all indexable fields out of that int[] into columns, and use indices on
those fields.

No doubt about that, querying tables using conditions on array columns is
not the best direction in most cases, especially when those tables are
huge.

Still, the interesting part here is that the OP claims this worked just
fine in the older version and after an upgrade the performance suddenly
dropped. This could be caused by many things, and we're just guessing
because we don't have any plans from the old version.

Tomas

Am 03.11.2011 17:08, schrieb Tomas Vondra:

On 3 Listopad 2011, 16:02, Mario Weilguni wrote:
<snip>
No doubt about that, querying tables using conditions on array columns is
not the best direction in most cases, especially when those tables are
huge.

Still, the interesting part here is that the OP claims this worked just
fine in the older version and after an upgrade the performance suddenly
dropped. This could be caused by many things, and we're just guessing
because we don't have any plans from the old version.

Tomas

Not really, Mohamed always said he has 9.0.3, Marcus Engene wrote about
problems after the migration from 8.x to 9.x. Or did I miss something here?

Regards,
Mario

Hi all,

Thanks for all your responses.

Sorry for late response

Earlier we used Postgres8.3.10 with Desktop computer (as server) and
configuration of the system (I2 core with 4GB RAM) and also the application
was slow i dint change any postgres config settings.

May be because of low config We thought the aplication is slow so we opted
to go for higher configuration server(with RAID 1) which i mentioned
earlier.

I thought the application will go fast but unfortunately there is no
improvement so i tried to change the postgres config settings and trying to
tune my queries wherever possible but still i was not able
to..........improve the performance..

So will it helpful if we try GIST or GIN for integer array[] colum
(source_detail) with enable_seqscan=off and default_statistics_target=1000?

Regards
Hashim

On Fri, Nov 4, 2011 at 1:37 AM, Mario Weilguni <roadrunner6@gmx.at> wrote:

Am 03.11.2011 17:08, schrieb Tomas Vondra:

On 3 Listopad 2011, 16:02, Mario Weilguni wrote:
<snip>

No doubt about that, querying tables using conditions on array columns is
not the best direction in most cases, especially when those tables are
huge.

Still, the interesting part here is that the OP claims this worked just
fine in the older version and after an upgrade the performance suddenly
dropped. This could be caused by many things, and we're just guessing
because we don't have any plans from the old version.

Tomas

Not really, Mohamed always said he has 9.0.3, Marcus Engene wrote about
problems after the migration from 8.x to 9.x. Or did I miss something here?

Regards,
Mario

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On Nov 7, 2011, at 7:21 PM, Mohamed Hashim <nmdhashim@gmail.com> wrote:

Hi all,

Thanks for all your responses.

Sorry for late response

Earlier we used Postgres8.3.10 with Desktop computer (as server) and configuration of the system (I2 core with 4GB RAM) and also the application was slow i dint change any postgres config settings.

May be because of low config We thought the aplication is slow so we opted to go for higher configuration server(with RAID 1) which i mentioned earlier.

I thought the application will go fast but unfortunately there is no improvement so i tried to change the postgres config settings and trying to tune my queries wherever possible but still i was not able to..........improve the performance..

So will it helpful if we try GIST or GIN for integer array[] colum (source_detail) with enable_seqscan=off and default_statistics_target=1000?

Oh dear! Where to even begin? There is no way to suggest possible solutions without knowing a lot more about how things are currently configured and what, exactly, about your application is slow. Just to address your particular suggestions, increasing the default statistics target would only help if an explain analyze for a slow query indicates that the query planner is using inaccurate row count estimates for one or more steps in a query plan. Depending upon the frequency of this problem it may be better to increase statistics target just for individual columns rather than across the entire db cluster. Setting enable_seqscan to off is almost never a good solution to a problem, especially db-wide. If the planner is selecting a sequential scan when an alternative strategy would perform much better, then it is doing so because your configuration is not telling the query planner accurate values for the cost of sequential access vs random access - or else the statistics are inaccurate causing it to select a seq scan because it thinks it will traverse more rows than it actually will.

In short, you need to read a lot more about performance tuning Postgres rather than taking stab-in-the-dark guesses for solutions. I believe it was pointed out that at least one query that is problematic for you is filtering based on the value of individual indexes of an array column - which means you actually need break those values into separate columns with indexes on them or create an index on column[x] so that the planner can use that. But if the problem is general slowness across your whole app, it is possible that the way your app uses the db access API is inefficient or you may have a misconfiguration that causes all db access to be slow. Depending on your hardware and platform, using the default configuration will result in db performance that is far from optimal. The default config is pretty much a minimal config.

I'd suggest you spend at least a day or two reading up on Postgres performance tuning and investigating your particular problems. You may make quite a bit of improvement without our help and you'll be much more knowledgable about your db installation when you are done. At the very least, please look at the mailing list page on the Postgres website and read the links about how to ask performance questions so that you at least provide the list with enough information about your problems that others can offer useful feedback. I'd provide a link, but I'm on a phone.

--sam

how about your harddisks??

you could get a little help from a RAID10 SAS 15k disks. if you don't even
have RAID, it would help a lot!

Lucas.

2011/11/8 Sam Gendler <sgendler@ideasculptor.com>

On 8 Listopad 2011, 4:21, Mohamed Hashim wrote:

Hi all,

Thanks for all your responses.

Sorry for late response

Earlier we used Postgres8.3.10 with Desktop computer (as server) and
configuration of the system (I2 core with 4GB RAM) and also the
application
was slow i dint change any postgres config settings.

May be because of low config We thought the aplication is slow so we opted
to go for higher configuration server(with RAID 1) which i mentioned
earlier.

I thought the application will go fast but unfortunately there is no
improvement so i tried to change the postgres config settings and trying
to
tune my queries wherever possible but still i was not able
to..........improve the performance..

As Sam Gendler already wrote, we really can't help you until you post all
the relevant info. So far we've seen a single EXPLAIN ANALYZE output and
very vague description of the hardware.

We need to know more about the hardware and the basic config options
(shared buffers, effective cache size, work mem, etc.). We need to know
how much memory is actually available to PostgreSQL and page cache (how
much is consumed by the application - as I understand it it runs on the
same machine). We need to know what OS it's running on, and we need to see
iostat/vmstat output collected when the app is slow.

Please read this and perform the basic tuning (and let us know what values
you've used):

http://wiki.postgresql.org/wiki/Tuning_Your_PostgreSQL_Server

Also post

So will it helpful if we try GIST or GIN for integer array[] colum
(source_detail) with enable_seqscan=off and
default_statistics_target=1000?

This is severely premature - it might help, but you should do the basic
tuning first. It might actually cause you more trouble. You've already
done this mistake - fixing something withouth veryfying it's actually a
problem - by requesting a RAID1 config. Don't do that mistake again.

Tomas