An evaluation of whether a system works well enough to be fit for purpose. Normally performance refers to the speed with which a system completes an operation or set of operations over time.
2
votes
1answer
59 views
PostgreSQL concurrent increment of counter
I need to maintain a statistical table for a project, composed by a list of items and their usage (Think about something like a website in which you would like to count pageviews). Each time an item ...
1
vote
1answer
69 views
Can putting mysql DB into memory or having the innodb_buffer_pool_size match the size of DB increase performance?
We have a mysql database that has roughly 80 gigabytes (GB) of data using inno_db engine. We are looking to increase performance on the database (we looked at the slow log and gone through and ...
0
votes
2answers
51 views
Reclaiming space from a large partitioned database
We have a database where one of the business group decided to remove several millions of rows as part of their upgrade process. (we removed for them..).. This database is partitioned based on a date ...
0
votes
0answers
36 views
Temporarly disable cache in oracle 11g
I want to disable the caching for my session in oracle 11g to see how long a query takes.
Is this possible or is there a better way for meassuring the time a query takes to run?
1
vote
2answers
86 views
sql server 2008 execution plan different on two production servers
We have two servers running SQL server 2008 R2, with identical databases, where we implemented a datawarehousing solution. The cube processing operation was taking a VERY long time in one of the ...
2
votes
3answers
127 views
SQL server disk write queue dramatically grows sometimes
I have SQL Server 2008 and a single database with full recovery model. Usually, the queue length is less than 1. But sometimes it grows up to several thousands (3000!!) for a few seconds. At this time ...
2
votes
2answers
90 views
How to implement posts with “seen by” like facebook?
Inside a Facebook group there is a feature when every time see the group newsfeed it mark all posts as seen by me.
And if I see a specific post inside a group thought a url ...
1
vote
1answer
85 views
SQL Server bulk insert performance
I’m running sql server 2012 and the installed ram on that machine is 128 GB. The performance of the bulk insert is very low. The bulk insert of 10 million records takes about 2 hours. We have checked ...
0
votes
0answers
31 views
The best approach to index dynamic query in MongoDB
I am working on log managment system where user will be able to upload logs from file. I have 'event' collection where I store all events from all sources (each source can have different log format ...
4
votes
1answer
99 views
How to determine if there are [idle connections with] uncommitted transactions in PostgreSQL?
According to a comment on this question I asked about idle connections in PostgreSQL 9.2, some uncommitted transactions (possibly related to some of those idle connections) might cause
some ...
3
votes
1answer
83 views
Could too many idle connections affect PostgreSQL 9.2 performance?
Some queries on my database server seem to take a long time to respond, and I believe the CPU usage is high. When running ps aux, I see ~250 "idle" connections (which I believe to be too many). I ...
0
votes
2answers
73 views
Why does using a variable make a difference in performance?
I have a table that constantly doing insert, and I am trying to run a delete script to remove old record.
The delete script looks like this:
DECLARE @StarDate DATETIME = '2013-01-13';
DECLARE ...
0
votes
1answer
108 views
What is the best way to insert a XML input to an oracle table in stored procedure?
I want to write a stored procedure which has a XML input (clob type) and inserts the data to a table. my XML structure is something like this:
<rowset>
<row>
...
0
votes
1answer
67 views
Mysql: order by field or select union?
As a newbie, I expected Mysql to return the rows of this query ordered by their ids order in the id clause
select * from test where id in (3,1,2)
Unfortunatelly for me, that's not true. The results ...
0
votes
2answers
71 views
Exploring and optimizing SQL performance of your system (PostgreSQL and Hibernate)?
Imagine you have inherited some project with extensive usage of SQL queries.
Let us assume that Hibernate is used as ORM and PostgreSQL as database, but thats not the point.
A question is: could ...
1
vote
1answer
83 views
Mysql DB server hits 400% CPU
I have been facing problem with my database server quite a month, Below are the observations that I see when it hits the top.
- load average 40 to 50
- CPU % - 400%
- idle % - 45%
- wait % - ...
1
vote
4answers
92 views
SQL Server 2008 DB Performance on single disk
I have a database in SQL Server 2008 with around 20 GB in size. And it is increasing rapidly.
Somehow I can not add multiple independent harddisks to increase IO performance.
If a add large table ...
0
votes
1answer
25 views
Modify legacy table schemas that have no primary key
I've been tasked with updating our database (SQL Server 2008) so that every table in it has a proper primary key defined. Due to various reasons over the years we have somehow built up some legacy ...
2
votes
2answers
106 views
Bandwidth comparison between log shipping and transactional replication
Which technique uses more network bandwidth:
Log shipping
Transactional Replication
Can some one share any benchmarks for the same ?
What would be the Memory and I/O impact on the Primary server ...
2
votes
1answer
125 views
Innodb Slow queries since convert from MyISAM
a few days ago we converted some write intensive tables from MyISAM to InnoDB hoping to have a better performance due the better locking system of InnoDB, but instead of gain performance, we start to ...
3
votes
1answer
103 views
Why is a hash match operator in this very basic query
I'm beginning to learn some about looking at execution plans and making queries more efficient
Consider these two basic queries
select distinct pat_id, drug_class, drug_name from rx
select pat_id, ...
-8
votes
2answers
136 views
How can I check for SQL Server performance problems using T-SQL? [closed]
I know how to use the Profiler, Performance Monitor, and Activity Monitor. I want to find a way to troubleshoot performance using T-SQL. How can I check for Microsoft SQL Server performance problems ...
1
vote
1answer
84 views
For a InnoDB only DB, which of these elements can be removed?
So, I'm trying to set up a Drupal 7 my.conf file that's combining best practices from various performance blogs. I'm realizing though that some of them are older than others, and many aren't assuming ...
2
votes
2answers
126 views
MySQL - Normalization over meaningless data - Compound Primay Keys or Surrogate ID field
Please forgive my title; if you have a suggestion for it, feel free to comment.
I have a database:
DROP TABLE IF EXISTS `books`;
CREATE TABLE `books` (
`isbn` VARCHAR(255) NOT NULL,
`title` ...
1
vote
1answer
36 views
Mysql performance for a nullable unique id column in a large table that references a record in another table
We have a large table of contacts (8 million records) that we promote to with mailings. When these people register we store them in a different members table. But we want to go back and update the ...
3
votes
1answer
258 views
Oracle insert through dblink performance issue
I'm trying to do an insert as select to a table via dblink. The query looks like this:
Insert into MARS_SUPERVISORS_PUB@EDHPUB
select
{...}
from edhper a, edhper b
where ...
4
votes
1answer
63 views
Oracle BLOB store performance
LOBs in Oracle are stored in-row when they are less than 4K in size and out-of-row otherwise.
I'm wondering how do SECUREFILE storage options COMPRESS and ENABLE STORAGE IN ROW work?
I have a lot of ...
6
votes
1answer
180 views
Landed as BI, but databases are a big WTF, what to do?
Maybe a duplicate, but I believe my case is a bit different. From one of the answers I got to this post on SQL Server Central that also comes handy too but is not quite the same scenario: 9 Things to ...
2
votes
6answers
395 views
SQL Server split mdf into multiple files
I have a database called example.mdf with a total size of 1GB which suffers from performance issues. I checked the allocated hardware and it is higher than required, I double checked the design and ...
3
votes
0answers
23 views
Does avg_query for PgBouncer include update and inserts?
Trying to tune our application and would like to know if the stats data that pgBouncer shows as avg_query, according to the PgBouncer docs on usage:
avg_query
Average query duration in ...
5
votes
1answer
69 views
RESOURCE_SEMAPHORE_QUERY_COMPILER waits in Microsoft SQL Server 2008 Enterprise
Could fragmented indexes on Microsoft SQL Server 2008 Enterprise cause RESOURCE_SEMAPHORE_QUERY_COMPILER waits?
The last two weeks one of our applications has had downtime due to ...
3
votes
1answer
59 views
Sql server snapshot isolation overhead when read_committed_snapshot is enabled
When SQL Server's read committed snapshot is on (and thus some amount of row versioning is necessary), is there any additional overhead caused merely by enabling snapshot isolation?
Snapshot ...
1
vote
1answer
65 views
Why does that query cause lock wait timeouts?
From time to time, I find a lot of these errors in my PHP error log:
MYSQL.1213: Deadlock found when trying to get lock; try restarting transactionSQL
The problem persists for about 2 or 3 minutes. ...
3
votes
1answer
111 views
SQL Server Performance Counters Relating to Disk Access and Log Files That Appear Concerning
I want to validate the optimal performance of our SQL Server and in doing so, I have gone through all the performance counters listed at the following link and create a trace log to analyze the data.
...
1
vote
3answers
142 views
When to periodically RESTART SQL SERVER 2008 R2? [closed]
So I've read that it's really a bad practice to restart SQL Server on a production environment..
Does restarting SQL Server speed it up?
Automatically restart SQL Server 2008
Why are periodic ...
3
votes
3answers
189 views
Investigating high SQL waits, especically LCK_M_U
Recently I have been struggling with SQL server performance and although we have fixed a huge multitude of basic errors in the config it is still performing badly. To clarify it is not overall ...
1
vote
1answer
158 views
Very slow DELETE in PostgreSQL, workaround?
I have a database on PostgreSQL 9.2 that has a main schema with around 70 tables and a variable number of identically structured per-client schemas of 30 tables each. The client schemas have foreign ...
6
votes
1answer
86 views
What is a good way to determine the performance I should expect from a PostgreSQL server?
Trying to figure out how I should expect my database to perform. Basically, I need to determine when the server I have set up is reaching its performance limits - which would help me plan server ...
1
vote
1answer
77 views
LOAD DATA INFILE on a MyISAM table blocks user read-queries, can we get around this?
I've got a large reference table, 100GB, in a MyISAM table, load it up from scratch goes well (4ish hours) using LOAD DATA INFILE.
But we have 1GB each day we want to update in a batch process using ...
3
votes
1answer
100 views
Can I use mysql to serve 100's of millions of small image files?
I need to serve 300,000,000 small image files totaling 1.5TB. Trying to unpack these files to individual files on the file system is next to impossible (1 MByte/sec throughput rates to create the ...
4
votes
1answer
78 views
After Rackspace server creation, PostgreSQL query planner doesn't work as expected
We created an image of one of our database servers in Rackspace. Then, we created a new server using that image, expecting things to work. However, the index performance we have seen seems to be ...
3
votes
2answers
83 views
SQL server performance and tuning
I am working on a system, there is a cisco load balancer that can handle 40K requests.
There are two app servers. There are 12 or so web services.
and there is a SQL server with 2TB of data.
...
5
votes
1answer
666 views
High Buffer I/O SQL Server 2008 R2 causes?
Am trying to troubleshoot performance on an SQL server that we have for our document management server and today performance has hit an all time low. Looking at the MDW I setup recently I can see a ...
1
vote
0answers
32 views
postgresql 8.3 possible checkpoint and memory misconfiguration
I am using postgresql 8.3 in a read/write heavy application where data are being written to the database from a background process while they are also being read/written from a web application.
At ...
0
votes
1answer
63 views
SQL Server weird issue with indexes and query planner
We had a bunch of crashes and restorations a few days ago and following those, the SQL Server DB has been acting strangely. We know that there were some issues with the failover clusters due to which ...
1
vote
0answers
56 views
How to make Greenplum 4.2.3 only scan the intended partition?
When I uses unnest() in a View, and uses that View in a select statement, Greenplum seems to fail in only searching for the intended partition and search through all the partition of the main table ...
1
vote
1answer
48 views
Most efficient way to sort data fields into SQL
I'm trying to decide on the most efficient way to sort various data values. Here's how the data arrives:
Device X sends a text string "name=value&name2=value&name=value"
On arrival that ...
1
vote
2answers
170 views
How should I tune Postgresql for 20 GB of RAM?
I've been fortunate enough to have the use of a 20GB Linode instance running Ubuntu 64 bit. I want to try to optimize PostGres for this service, but I don't know what I should prioritize changing.
I ...
0
votes
0answers
363 views
'Incorrect datetime value: for column 'last_login' at row 1'
i am getting below error:
Last_SQL_Errno: 1292
Last_SQL_Error: Error 'Incorrect datetime value: '2013-03-10 02:00:00' for column 'last_login' at row 1' on query. Default database: 'platform'. ...
3
votes
2answers
69 views
Load Testing Crash Course
Can someone point me at a good resource to get a crash course in load testing. I have a sql server machine that I need to load test but I havent been thruogh the process before. Also we do not have ...
