New answers tagged performance-tuning
5
votes
Stored Procedure Tuning Help
The Potential Problem
At a quick glance at the execution plan and what the code is doing, it looks like one of the main issues is your JOIN clause to [maxims_prod].[dbo].core_patient_c_identifi:
LEFT ...
- 30.4k
0
votes
Is a performance improvement for this query with subselect possible?
There is a way to solve this with a single logical hit on the table, keeping the OR condition though. It may or may not work faster. The solution requires MySQL 8+ as it uses a CTE and the ...
- 22.3k
2
votes
Accepted
Is a performance improvement for this query with subselect possible?
Two problematic constructs: OR and NOT IN ( SELECT ... ). This addresses both:
( SELECT *
FROM fruits
WHERE customer_id = 1
)
UNION ALL
( SELECT *
FROM ...
- 73.8k
3
votes
Accepted
Does a select within a where clause affect performance?
No, the same principle doesn't apply in the example you gave. The optimizer will generally try to convert that type of predicate against a derived table into a set-based construct like a JOIN or ...
- 28.5k
0
votes
Why is MariaDB innodb_flush_method = O_DIRECT so much slower than fsync for SELECT count(*) as count?
(Not an Answer, but too long for a Comment.)
What filesystem? ZFS, EXT, etc? Does it have "journalling"?
Set innodb_buffer_pool_size to about 70% of RAM (say, 40G). 128M is ridiculously ...
- 73.8k
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