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.

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Significant difference between duration for querys in SHOW PROFILE and SHOW PROFILES?

I have use mysql profiler to optimize an opencart query which takes more than 10 seconds to executes. mysql> SHOW PROFILES; ...
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1answer
71 views

Slow INSERT/UPDATE on InnoDB

I have a problem with the performance of my MySQL server, let me explain: I instaled a MySQL server, version 5.5.20 Server version: 5.5.20-log Source distribution SELECT queries runs fast on ...
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75 views

Why is this query stuck if there are no waits?

I am working with a vendor's activity logging system. One of the tables has 70+ million records and is constantly increasing at several hundred records per minute. They have a utility to delete old ...
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1answer
65 views

Oracle: index vs. table stats [closed]

In Oracle, when would I want to gather index stats, instead of just gathering stats on the table? In which use case would index stats make a difference?
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1answer
300 views

Improve MySQL Query Performance - Too many records

I am using MySQL RDMS for a contact management system. Now a days my database grew in size and contains more than 1 million records. Checking duplicate phone numbers became a big issue during ...
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1answer
278 views

MongoDB insert performance rapidly dropping

I'm currently experiencing a rapid decrease of the insert Performance. I have a rather simple data model { "Id": "ObjectId", "SomeProp": "xy", "SomeTags": [ { "key": ...
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55 views

Oracle: separate column histograms for partitions

I have a partitioned table like MY_TABLE(PART_KEY, DATE_KEY, ...) with a local partitioned index on (PART_KEY, DATE_KEY). When I collect stats on the table, I end up with a HEIGHT BALANCED histogram ...
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70 views

SLEEP_TASK and PAGELATCH_XX peaking after upgrade to R2 SP1

I wanted to just add a comment to this question: SLEEP_TASK Wait Type in SQL Server - What does it indicate? But I'm having not only SLEEP_TASK wait but also PAGELATCH_SH and PAGELATCH_EX wait types. ...
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2answers
172 views

DBCC CheckDB causing high values for resource_semaphore wait type

On one of our production server, where SQL Server 2008R2 (Service Pack 2) is installed with 24 GB memory and 24 CPU cores grouped into two NUMA nodes, we are facing high counts for resource_semaphore ...
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1answer
127 views

Oracle using index on partitioned table when full scan would have been better

Trying to make some sense out of this observation in Oracle. Query: SELECT ... FROM MY_TABLE WHERE PART_KEY=x and DT_KEY between 20120101 and 20120731 Uses an index scan on PART_KEY/DT_KEY, even ...
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2answers
99 views

Seeking help to test a use case on sql server memory

This is a question which came out of curiosity to know of how sql server handles memory. Assume I set a very low value for max server memory and I increase my workload like running dbcc checkdb, ...
2
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1answer
117 views

poor and/or unreliable InnoDB performance

I recognize that there are a ton of posts like this, but after reading up on InnoDB performance problems, nothing I tried has helped. I have a database containing four InnoDB tables. The largest ...
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23 views

How can I determine the performance (rows/second) for a certain query on one of my tables?

I want to find the performance (rows/second) for an UPDATE query on one of my tables so I can adjust my WHERE clause to select an appropriate number of records. The table has around 10 million rows. ...
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1answer
70 views

Slow queries InnoDB occasionaly

I have the next table: CREATE TABLE `sessions` ( `session_id` char(32) COLLATE utf8_unicode_ci NOT NULL, `session_expires` int(11) NOT NULL DEFAULT '0', `session_data` varchar(10000) COLLATE ...
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2answers
105 views

Disk I/O Activity

Resource Monitor on our SQL Server DB server shows very high fluctuating disk activity that I cannot understand. I then check Activity Monitor and the Database I/O looks ok. Any ideas why I am seeing ...
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1answer
57 views

Insert (write) performance

We are trying to speed up the queries in our application and in the process identified all queries which took more than 100ms. We noticed that there were few insert statements which took more than ...
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1answer
42 views

Why is logging “slow”?

On an empty transient table, inserting a single row took 50ms before changing it to UNLOGGED, 1ms afterwards. Why is this exactly? If the table structure is necessary, I'll post it, but it's only ...
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3answers
147 views

MySQL: How to avoid case sensitivity in SQL queries when migrate from Windows to Linux?

I have migrated my Database from Windows to Linux server. In many places, query has been written without focusing their cases (uppercase / lowercase). So, these queries are not getting executed and ...
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1answer
597 views

Does SQL Server allow INSERTs into tables and indexes to be written in parallel?

If I have a table that has many indexes, and I run a statement that inserts rows into the table, will SQL Server insert rows one-at-a-time, or will the rows be inserted using parallelism?
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1answer
43 views

Is it OK to duplicate parent field in child table for performance?

I have a very complicated query which involve more than 10 tables. Some parent tables are loaded only to search on one field. I wonder if I can copy this field in the child table (this data is never ...
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30 views

Performance Metrics for TempDB [duplicate]

I've been tasked with gathering performance metrics on a few database servers that have one TempDB data file. It seems prevailing wisdom is to have one TempDB data file per core up to a certain ...
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1answer
101 views

How to speed up looped INSERT INTO statements?

I currently use the following statement, for 10,000 rows it takes about 150 seconds. I tried removing the index on the target table, but this didn't help. Running the loop without the INSERT INTO ...
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1answer
726 views

Is SQL*Net message from dblink > 30% a performance issue?

I have a Java web-application running under Glassfish. App accesses Oracle using JPA (eclipselink). Last 2 days I'm observing some perfomance issues: some messages about long running queries (10 to ...
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1answer
105 views

Do triggers affect DB performance

I have a database with 250 small and medium sized tables. These tables are related with both MyISAM and InnoDB storage engines. There are multiple triggers that have been created on different tables. ...
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1answer
85 views

Will adding more indexes speed up using RedGate SQL DATA compare?

We want to use RedGate's SQL Data Compare to migrate user data from one DB to a DB on a completely different provider. This will be a time-sensitive operation as we do not want our site offline for ...
6
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1answer
607 views

Database design for handling 1 billion rows and counting

We receive real-time GPS data at a rate of around 5000 pr. minute (from 4 TCP servers). Each server uses a single connection to insert the data, and buffers data in between inserts. Every 15 minutes ...
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1answer
133 views

Optimizing a large number of INSERT … SELECT statements

I have a MySQL InnoDB database with two tables related by a foreign key. Each time a row is inserted into one it uses an INSERT ... SELECT statement from the other to get the corresponding foreign ...
2
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1answer
971 views

SQL Server PerfMon: Compilations/sec > Batch Requests/sec

I've been looking at various PerfMon metrics on one of our client's SQL Server instances trying to get a good gauge of where our database (or server) could use improvements. One measure that has me ...
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36 views

more queries vs storing results in database

Environment: Embedded (smartphones) Data Structures: Object Table A: id, field1, field2... Object Table B: id, field1, field2... Object Table C: id, field1, ... , Object A, Object B ... many ...
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1answer
74 views

What are possible causes for consistently volatile INSERT performance in MySQL tables?

I have a Java program running on a VM that is sequentially feeding a queue of single row INSERTs through a single connection to a MySQL server on the same VM. The queue execution is not artificially ...
2
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1answer
53 views

How to efficiently count rows in a query by limiting the number or found rows?

I have a website where I output a pagination with a limited number of pages, let's set it to 50 for example. That is, if there are actually 51 or more pages of content the 50th will be the latest that ...
8
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2answers
264 views

Why would MySQL do serial synchronous I/O?

When looking at a particularly annoying query over MyISAM tables which takes a long time to execute on a number of occasions, I have noted that MySQL seems to expose a rather strange I/O pattern: when ...
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1answer
59 views

Is a single batch request equivalent to a single tsql request?

I'm looking into some performance metrics and every recommendation includes monitoring Batch Requests/sec. But, maybe a silly question, does a singe batch request correspond to exactly one tsql ...
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1answer
62 views

How to prepare executon plan for given sql query on a server with 4 processors (Oracle database)

4 processors means the query runs in parallel. Select /*+ parallel(4) */ T1.A FROM T1,T2,T3 WHERE T1.A = T2.A AND T1.B=T3.B AND T1.C=T3.C Tables T1,T2 and T3 have 4,8, and 16 partitions ...
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2answers
300 views

SQL server query is slow *without* including execution plan

I have just set up fresh installation of SQL Server 2012 on a new server and I'm experiencing very strange performance problems. Long story short, for some reason not including execution plan makes my ...
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3answers
422 views

best practice for 'staging' relation in stored procedure: use temp table, or view?

When I write stored procedures that take relation A and output relation Z, I like to create 'staging' relations along the way, so I can inspect the state of the data after each step in the programming ...
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1answer
186 views

PostgreSQL - Out of memory on count group by query

I'm trying to execute the following statement in PostgreSQL database: create table tmp_nodes as select node_id,count(way_id) as count from way_nodes group by node_id; This query fails because the ...
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60 views

Adding additional condition significantly degrades performance

Have the following query: SELECT * FROM table_A INNER JOIN table_B ON /* conditions */ INNER JOIN table_C ON /* conditions */ INNER JOIN table_D ON /* conditions */ WHERE table_B.state = 'active' ...
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1answer
97 views

SQL Server - Data and Log Separation

We have a SQL Server 2008 R2 which has, among others, a 12K RPM HDD and a 7.2K RPM HDD. The original intention was to store the data files on the 12K drive and the log files on the 7.2K drive, as is ...
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2answers
347 views

Major Discrepancy Between SQLIO IOPS/Throughput Stats and DBCC CHECKDB Operations

I'm conducting time trials on a new SSD array running both SQLIO tests and a real-world workload of DB restores and DBCC CHECKDB calls. I'm seeing a major discrepancy between the IOPS and throughput ...
2
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1answer
134 views

Need help tuning my.cnf file

I need help tuning mysql. Currently it is using a lot of CPU. I dont find any query that last longer than 3 seconds in SHOW PROCESSLIST and there are only around 20-25 running most of the time. Still ...
2
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2answers
91 views

Does having many databases affect MySQL performance?

I have huge unused databases in MySQL. Do they affect my MySQL engine performance even if they are unused? Do they consume memory on their own? Thanks
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0answers
281 views

Are mongodb bulk inserts really increase server perfomance (and faster)?

Bulk inserts always are faster in client side because of saving round-trips, but at the server-side is there any sensible performance improve? It seems the code for bulk inserts, just loops over ...
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195 views

Best design of mongo replica set for DB read/write speed

I'm building a Node app that uses MongoDB. Whilst it would probably be fine to have node and mongo sitting on the same VPS, I want to ensure that the MongoDB is backed up and maintain high ...
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2answers
67 views

Index is not used with same Query on two Servers [closed]

I have two notebooks with same specs (same model, only ram is 24GB/32GB, same ssd) and exact same database and same sql server version. SQLIO is 3300 and 3600. Now I run a query on one notebook and ...
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1answer
167 views

Optimistic Paging and separate query for COUNT?

I am using SQL SERVER 2012 FETCH/OFFSET after searching a lot that this will give me the best performance. But for paging to work, I need a Total count. There are 2 ways to achieve this. 1) Paging ...
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1answer
111 views

Optimizing a slow MySQL query

I'm trying to optimize a ~100GB database. All data values are in one single innodb table, is this bad? Here's what a common query looks like: SELECT `CensorCode`, `LocalDateTime`, `UTCOffset`, ...
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94 views

Any way to speed up my queries in MariaDB with tables less than a 4 GB in size?

I'm doing some text mining work and a bit frustrated that queries are taking 6 to 10 minutes to run. My workstation has a 3.5ghz Xeon, 32GB of RAM, and 2 SSD as RAID 0. Is it possible to do ...
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1answer
62 views

How can I rewrite the following removing the date_format function?

I have a table with a column when that is of type datetime. I am doing the following filter which can not use and index: AND DATE_FORMAT(t1.when, '%Y-%m-%d') <= LAST_DAY(now() - interval 1 month ) ...
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1answer
65 views

Impact of replication compression & encryption on performance, traffic?

What is the impact of MySQL compressed-slave-protocol on replication traffic? According to High performance MySQL it can lower the traffic to a third of the same replication without the compression. ...