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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109 views

Limit distinct count of group by

Suppose for simplicity that I have a table t with columns id and value. I can find the ids that have more than one distinct value using a query such as SELECT id, COUNT(DISTINCT(value)) AS count FROM ...
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36 views

Did I Properly Diagnose That It's Not A SQL Server Issue?

We have a job that populates about 450,000 rows nightly in an update/insert job via a stored proc nightly. The .Net app pulls in data from a noSQL DB via an API call then pushes it out via a stored ...
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2answers
66 views

Can an EXISTS clause be improved when the condition is checked for the same value multiple times?

Assume that I'm modelling a Blog engine. Blogs have n Posts. Each User can be granted a role on different Blogs (Admin, Approver or Editor stored as enums/ints). Each Post can have a State (Draft, ...
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1answer
66 views

How to Implement Different Object Types as Similar Tables?

I have a database I am attempting to design. I am trying to determine the best approach to declare similar, but different types of objects, each with their own sets of properties (perhaps some ...
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15 views

How to find an application for a specific system?

I have a distributed storage platform that I wanted to test. I launched a benchmark (i.e. IOzone) over it, given the following workload: I/O size = 4kB, 100% read, and 100% write, random access. ...
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2answers
149 views

Is it possible for increasing the SQL Server max memory limit to degrade performance?

As far as I can tell, raising the SQL Server max memory limit has no drawbacks, provided that sufficient memory is left for the OS and other applications. Assuming this is the case, can there be any ...
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1answer
81 views

How database buffer pool work?

For example we have 2 scenarios: Scenario 1:- We have very small buffer pool size of 100MB. My query data is 500MB. Does the system keep 500MB query data in RAM such that a new ...
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0answers
460 views

Application running slow when querying against SQL Server 2008R2

I'm having an application that is starting to run really slow when inserting and querying data from a SQL Server. The database is on a dedicated virtual box with 10 GB ram, AMD Operon 6134 processor ...
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1answer
331 views

PostgreSQL 9.4 analysis, performance of normal column, indexed column and jsonb key

If I have a table containing: CREATE TABLE test( id SERIAL PRIMARY KEY, name VARCHAR(200), age INT, data JSONB ); and data column populated with {"name": xxx, "age": yyy}, sometimes ...
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132 views

Galera cluster consume many CPU percent and CPU high load

I have implemented a cluster include three nodes: two stored nodes and one garbd (also haproxy - load balancer). Some information about servers: SSD 480G Raid1 Memory 32G Swap 16G 2xCPU, number of ...
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1answer
91 views

my.ini configuration for a huge server

I have developed a web based app in PHP MySQL and Flash Builder. It was running fine until a few days ago when the client began to connect a lot of users. Then the app started to freeze and sent ...
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3answers
93 views

How can I speed up an sql query that round trips between two tables

These tables are not that big, but the time taken to process this query is long. What can I do with the following queries to speed up the process taken to return results? $msc=microtime(true); ...
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1answer
237 views

Columns count in SELECT query and SQL Server buffer cache

Let's assume that I have a table with 30-50 millions records. It has ~40 columns. Currently when I request data it always requests all columns because of legacy ORM that we use. I know that if we ...
3
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1answer
124 views

Help with indexing narrow table with many millions of rows

I have a good amount of experience with SQL Server, but not much with indexes and I fear I'm a little bit out of my depth in trying to figure out how to correctly structure a table that has 100+ ...
2
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1answer
379 views

Query shows SELECT 0

I'm looking through the queries being executed by a third party application. The application was flagged as being slow by some of our end-users. It seems to INSERT records into a HEAP, then DELETE ...
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0answers
83 views

Optimizing postgres row overlap constraints involving UUIDs and GIST

For various reasons all my tables have UUIDs as primary keys and I need to exclude duplicate rows where the combination of area_id, user_id, and finished_at <-> started_at window. The only way I ...
0
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1answer
120 views

Increase performance WITHOUT adding indexes [closed]

I'm having a rather large table (350MB, 1.3M rows) and there are dozens of queries arriving at this table every second. Most queries are super-fast thanks to indexes - but some others aren't. ...
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3answers
58 views

MySQL select with between optimization

I got issues with some geo IP query. So basically here is create code of table: CREATE TABLE `geo_ip_city` ( `id` INT(5) UNSIGNED NOT NULL AUTO_INCREMENT, `begin` BIGINT(20) NOT NULL DEFAULT ...
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2answers
33 views

MySQL rapid Data Replication from multiple Databases

I am a Freelance Web Developer but not a Database Administrator at all except basic Database Operations like DML etc. Today I got a client asking me to develop a Web based application but there is a ...
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1answer
136 views

MongoDB Insert Performance

I have some data which are aggregated in chunks and later pushed into another collection. The problem is that aggregated data pushing to another collection is very slow and takes from few hours and i ...
1
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1answer
192 views

Can I trigger events based on timestamp data or should I use polling?

I'm asking this question for SQL Server 2008+ but this could really be for any DBMS. Imagine you have scheduled data, something like: ID Data Timestamp 0 NULL 2014-11-22 1 ... ...
1
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1answer
335 views

postgres materialized views and indexes to improve aggregate performance

I have a large table with a number of materialized views used for pre-calculating aggregates. New data is inserted only once a day so think of this as a data warehouse type system. Obviously when I ...
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0answers
32 views

Allowing users access to SQLPLUS and to compile PLSQL [duplicate]

As a DBA - assuming my users are knowledgeable with PLSQL and SQL - why would I not grant my users privileges to compile and run their own PLSQL code. We have an MI database environment where the data ...
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0answers
252 views

SQL Server spending a lot of time creating sp_dbmmonitorupdate

I have an SQL Server 2008 R2 Standard with around 80 databases, 18 of which are a synchronous mirror primary. I'm having a lot of complaints about database speed lately, so I've started digging with ...
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1answer
45 views

MongoDB Tag-Aware Sharding Workflow

I wonder the work flow of sharding cluster in Tag-Aware Sharding. --- Sharding Status --- sharding version: { "_id" : 1, "version" : 3, "minCompatibleVersion" : 3, "currentVersion" ...
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0answers
151 views

MySQL 5.6.19a InnoDB Concurrent Insert [closed]

I've looked through most of the threads on this topic but still had question I was hoping someone would be gracious enough to help with. I am seeing low CPU usage and write latency but transaction ...
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1answer
68 views

Similar hardware, Same DBconfiguration and Database but different status variables result between Windows and Linux server [closed]

I have two database servers - one is Windows - 2008 and another is RHEL5 with similar hardware configuration. Both OS are 64 bit. MySQL 5.1.58 community edition is installed on Windows servers while ...
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1answer
255 views

Improve the insertion rate of mongo sharded cluster

I can't disable the write concern while i mongorestore with .bson file. It totally damages the insertion rate (insert/sec). This is my sharding status. mongos> sh.status() --- Sharding Status --- ...
4
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1answer
195 views

AlwaysON : Log_Send_Queue_Size is increasing but the log_send_rate keeps decreasing?

Question Why, despite the increasingly log_send_queue_size for these two databases, did the log_send_rate keep decreasing? There were no bandwidth issues on the network at this time, and no other ...
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0answers
61 views

SQL Server is very slow [closed]

In company with 30 clients(computers), after 3-4 hours working with financial software, SQL Server is very slow SQL Server can not free used memory and the query execution time is very slow but after ...
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0answers
99 views

PostgreSQL queries slower than before?

I am using PostgreSQL 9.3 server on my production server. Everything had been working fine for the past couple of months. But since the past week or so, PostgreSQL seems to have becomes very slow with ...
1
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1answer
140 views

Localization: One table or multiple tables? (MySQL)

I need to be able to store string messages in various languages. I guess I need a column for each language string. For example my columns could be: ID | message_EN | message_DE | message_FR Now, I ...
0
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2answers
46 views

SQL Performance: COUNT or extra attribute?

If I want to count the number of a multivalued attribute, which way is faster: a) using COUNT(attribute) on a whole table or b) adding an extra attribute which counts these stored values (to be ...
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0answers
88 views

Multiple databases with medium tables or Single database with huge tables

I've developed a shop management software using Postgresql and JAVA. I would like to know which of the solutions below is the best one for my specific situation: Only one database with huge tables ...
1
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2answers
110 views

Simple query is slow on 4M-rows table

I have in production a MySQL table pageviews with 4M rows that records page views of users on posts. I need to know which posts a specific user have read, but this request takes up to 15 seconds to ...
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0answers
85 views

Looking for a recipe to merge multiple rows to single row

I have a aggregation table that is written by multiple processors (around 20). Each row has a composite key - location-id, campaign-id,... and aggregate stats about it. I need to merge the ...
1
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1answer
79 views

Will switching from Concrete Table Inheritance to Single Table Inheritance improve the performance of my queries?

I currently have an application that allows people to view and share 10 different types of posts (ex SportsPost, WorldNewsPost, TechnologyPost, etc). All posts types are conceptually the same, but ...
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1answer
128 views

SQLAnywhere: Visualize in real time CPU and RAM consumption of sql connections

I want to keep track of which connection use most of resources. Within Sybase Central (SQL Anywhere 9, 12), for each server and database, we have pane to check in real time All Connected Users and ...
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0answers
84 views

Very poor MySQL query performance after upgrading from server-5.5 to server-5.6

I'm in the process of trying to migrate a database from an old server to a new one. The old server is running an Xampp installation which has been more than adequate for the use case. For the new ...
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1answer
498 views

Query optimization for multiple joins postgres

ER Diagram Brief description The database to be used is postgres. The database might contain upto 2 million AccountHolder records. Since the AccountHolder table is accessed and updated frequently ...
0
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1answer
34 views

MYSQL improve query performance when using OR

I have a very simple MYSQL table with 2 columns and I run this query: SELECT * FROM table WHERE (col1 = '123' AND col2 = '456') OR (col1 = '456' AND col2 = '123') Col1 and ...
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2answers
30 views

MySQL improve query syntax

I have this simple MySQL query: SELECT * FROM table1 INNER JOIN table2 ON table2.col = table1.id WHERE table1.id = '123' id is the primary key in table1. table2 has composite primary key of two ...
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0answers
85 views

Can High CPU be triggered by Login Failures?

On our SQL Server (used for TFS) we have recently had the CPU pegged at 100% (with a few occasional dips) for nearly a day and a half. Looking at the SQL Logs, there appears to be a correlation in ...
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0answers
68 views

Billion records mysql performance with large result sets

I'm currently developing an application which will have several mysql tables where 3 of them have very large amounts of records. The thing is that my app will have to sync each account on a hourly ...
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1answer
43 views

Mathematical or Computing Alternatives for MySQL Combination Queries operating toward their Performance Limit

We regularly run a contest that is becoming quite popular. In the contest, we need to select the combinations of contestants from 8 groups whose cost is under a threshold, and who combined have the ...
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2answers
121 views

Signal wait always high

I'm not sure if this is the right place to ask this question, so apologies in advance if not. Problem I'm facing is: One of my server's signal wait floats at around %35 and won't go down. Top 3 ...
4
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3answers
2k views

Keeping default max memory 2147483647 MB value in SQL Server, a bad practice?

Based on that msdn page : server memory settings it's a good practice to keep the default values for SQL-Servers min and max memory to keep it dynamic... From what I learned through tutorials you ...
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2answers
97 views

PostgreSQL and storing configs

The problem is to store and use global configs such as currency/date format etc. Since this functions are commonly called I'm concerned with the performance impact. Lets take currency as an example. ...
5
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3answers
372 views

SQL Server clustered index, index balancing and insert performance using NewID

I have a large (6db) trace table. It has a clustered key (DateTime) which is created through GETDATE(). The connection pool for connections to this database/table rises as high as 50 on average ...
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2answers
941 views

Transaction speed benchmarks for mySQL v5.6 replication - seems very slow

I'm trying to select the best configuration for our new infrastructure but got a bit confused about the results. I used sysbench v0.5 for the tests: prepare data sysbench ...