Basically
1. if you join table try to filter out as much as possible in WHERE (to
reduce amount of data sent form map to reduce step)
2. if you join big table with small table (< 500 MB) use SELECT /*+
MAPJOIN(small_table) */ hint to avoid reduce step.
3. if you join big table with big table make
Hi,
Can you please paste the output of "explain" for both the queries so that
we can know if the predicate is being pushed down in both the cases.
Thanks,
On Fri, Jun 14, 2013 at 10:05 AM, Naga Vijay wrote:
> Hi,
>
> Here are the test results for the two query options shown in my initial
> em
Hi,
Here are the test results for the two query options shown in my initial
email -
Test Criteria - Both tables have 20 million rows each, 20 partitions, 16
buckets for item_id
Query Option 1 - Took 25 minutes, 5 seconds
Query Option 2 - Took 24 minutes, 42 seconds
Thanks for all the responses!
You can use "explain" for confirming differences. For inner joins, it
would make the same plan.
2013/6/14 Igor Tatarinov :
> I would expect no difference because of predicate pushdown.
>
> igor
> decide.com
>
>
> On Thu, Jun 13, 2013 at 11:31 AM, Naga Vijay wrote:
>>
>> Sure, Will do
>>
>>
>> On
I would expect no difference because of predicate pushdown.
igor
decide.com
On Thu, Jun 13, 2013 at 11:31 AM, Naga Vijay wrote:
> Sure, Will do
>
>
> On Thu, Jun 13, 2013 at 10:42 AM, Stephen Sprague wrote:
>
>> Hi naja,
>> test those two versions (or three now) and report back to the group.
Sure, Will do
On Thu, Jun 13, 2013 at 10:42 AM, Stephen Sprague wrote:
> Hi naja,
> test those two versions (or three now) and report back to the group. :)
> even if some smarty-pants thinks he knows the answer its always good to
> confirm things are as they should be.
>
>
> On Wed, Jun 12, 201
Hi naja,
test those two versions (or three now) and report back to the group. :)
even if some smarty-pants thinks he knows the answer its always good to
confirm things are as they should be.
On Wed, Jun 12, 2013 at 11:54 PM, Sanjay Subramanian <
sanjay.subraman...@wizecommerce.com> wrote:
> Hi
Hi
I would actually do it like this…so that the set on the left of JOIN becomes
smaller
SELECT a.item_id, a.create_dt
FROM
( SELECT
item_id, create_dt
FROM
A
WHERE
item_id = 'I001'
AND
category_n
