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1answer
677 views

Why is hash join slow in postgresql 9.1?

I transfered my DB from Postgresql 8.4 to new server with Postgresql 9.1. Size of DB is 9.9GB Data directory is situated on ssd 60GB disk. And server has 16GB RAM and 16 proccessor cores. But today ...
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1answer
1k views

MySql turning - “Select full join” is too high - How to identify the queries causing this

We're trying to manage and tune our MySql. One alert we're getting in phpMyAdmin is this: Select full joinDocumentation 421 The number of joins that do not use indexes. If this value is not 0, ...
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2answers
258 views

MySQL query caching - what happens if Server runs out of RAM?

so I have enabled query caching on my server but now from the 8 GB RAM there is almost non left! CPU is around 3% ! Now what happens when there is no more RAM left? Will this just increase CPU load? ...
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3answers
185 views

True or False: a table with large records (rows) and lots of fields (columns) will take longer to return a SQL query? [closed]

True or False: a table with large records (rows) due to lots of fields (columns) will take longer to return a SQL query? That is, if I have a SELECT ... WHERE...query in SQL that operates on a table ...
3
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1answer
829 views

Speed up MySQL inserts with partitions on MyISAM with unique key

I have a large MyISAM table (~30M rows). At some point I've switched it to fixed row format, so now table takes ~40Gb on disk and 2Gb for indexes. Table has a unique index and there are 100 'insert on ...
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1answer
35 views

If i were to develop a software for DBA's to help them in query optimization, what features could i incorporate? [closed]

What would be your expectations from such a software. I am planning to show the DBA a list of the top cpu and memory intensive queries along with the query plan, etc. How could i assist the DBA more ...
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2answers
599 views

Switching on MySQL query profiler for a website?

I want to "swtich" on the sql query profiler for my php/mysql site and leave it ru nnig for a while. The idea is to capture usage details over a day and then analayze the queries and work out which ...
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4answers
90 views

Requesting Oracle DBA to use SCSI instead of IDE

We want to improve the performance of our oracle database which stores around 10 TB and is OLTP. I noted that the Oracle server uses IDE hard drive, and have heard that SCSI is faster than IDE. Will ...
0
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1answer
985 views

Weird MySQL query plan: why is this query using temporary & filesort? How to optimize it?

I have a query: SELECT * FROM amp_ads,amp_c,amp_c_countries WHERE (amp_c.zone = '24' OR amp_c.zone = '25') AND amp_ads.ad_complete = '1' AND amp_ads.ad_type = '17' AND amp_ads.accept = '1' ...
1
vote
1answer
153 views

how to make a server that handles 1000 clients [closed]

I am looking for server software to handle data for thousands of clients (internal company employees). This server should be multi-threaded to handle all the clients with good client overhead ...