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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1answer
105 views

What does a “Buffer cache hit ratio” of 9990 mean?

I got this query from a blog post: SELECT object_name, counter_name, cntr_value FROM sys.dm_os_performance_counters WHERE [object_name] LIKE '%Buffer Manager%' AND [counter_name] = 'Buffer cache hit ...
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0answers
29 views

Replication / Bulk Update between Servers

I'm looking to update several tables between two servers daily to have a replica of the data available. My question is, what is the least resource heavy and most effective method to implement this? ...
0
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1answer
173 views

Compare two big tables in PL/SQL

I need to implement comparing 2 tables by set of keys (columns of compared tables). By this comparing i should check equal records (equal = equal by set of defined keys (columns in these input ...
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2answers
77 views

Preventing sysquerymetrics from being created ASE 15.7

Can I prevent Sybase ASE 15.7 from creating the sysquerymetrics view for a database upon creation? And also, if the view is dropped how can it be added later?
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2answers
329 views

Perl - MySQL/MariaDB - slow with no identifiable bottleneck

I am running a Perl script (using DBI) which reads from raw files from a hard disk, and updates MySQL database (which is on a separate SSD). My performance is rather slow (1000 files processed in ...
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4answers
630 views

At What Point Should I Split or Partition a Very Large but Simple Table

Our site has some large but simple (INT, INT, DATE) tables for stats. Each table has up to 300,000,000 rows, and gets bigger every day. The hosting provider has suggested that we split or partition ...
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2answers
125 views

Unexpectively slow data loading into Oracle

Big amount (4.000.000+) of files (1-4Mb each) are loading into Oracle 10g for about several days. Table is allocated in big tablespace, which was created on special volume (labeled BIG_VOL) over ...
2
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1answer
53 views

Resource cost of a blocked query

I'm currently reviewing a case where an SSRS server is experiencing frequent blocking and deadlocking. The reports are not business-critical, and they are frequently killed to alleviate the blocking. ...
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2answers
1k views

Join on dm_db_index_physical_stats very slow

I'm running a small query below in a MS Dynamics AX 2012 database and it runs more than 5 minutes which I had to cancel and it is showing PAGEIOLATCH_SH wait type. The database data file is 560GB and ...
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1answer
128 views

How can I measure the number of IOPs for a certain query

I need to estimate the max IOPs for a certain MySQL DB (one that does not exist yet). The OS is Linux and the DB is MySQL 5.1.x (though I don't think the DB brand is important for the asked topic) ...
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0answers
49 views

Can CTE sub-statements be prevented from executing at all?

Through this strategy, time consumed by queries for my application have dropped to extreme lows; however, some queries consume more milliseconds than necessary. The reason why is that upon ...
1
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1answer
110 views

optimize design for a table with 50 columns [closed]

I have a table with 50 column and one of my friend has told me to split the table in 4 different table to save 12 column in each table. He proposed a design to have Master table and refer the PK of ...
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2answers
99 views

How to tune the below query

I am currently working on below table structure to pull the data/ generate any one time report. Let us consider the table name to be ABC. ID Field Value 1 Name Nagarjuna 1 Gender Male 1 ...
2
votes
1answer
120 views

Prepared statement overhead

I am using libpqxx to communicate with a PostgreSQL 9.3 server. For multiple table inserts, if they are split into individual prepared statements, they cost approximately 2ms each. If they are all ...
3
votes
1answer
48 views

Best Design for this “Sweepstakes” Project?

Hello there fellow developers, Merry Christmas first aff all, and i hope you will have a happy new year soon. :) I was having more or less a problem with an idea that came to my mind. I am currently ...
0
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0answers
142 views

Oracle - Slow queries without prepending schema name or providing hint

I am logged in as the schema owner in Oracle 11gR2 on Linux. I have 55 million rows in table. select max(col) from table; - takes 300 seconds (index full scan) select max(col) from schema.table; - ...
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5answers
4k views

Is it advantageous to scale out using multiple SQL Server instances on the same server?

For a use-case of 9 databases spread across 3 time zones, is it advantagous to spread the databases onto multiple SQL Server instances on the same server? What will I gain and what will I lose? ...
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0answers
65 views

Data warehousing: data transfer process too slow with larger batches

I have two primary instances of SQL Server, one for OLTP and one for reporting. The data warehouse for reporting is basically a Type 2 SCD: every table has DWDateStart and DWDateEnd columns and the ...
0
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0answers
62 views

What minimum RAM should the server have for a Django application with Postgresql server?

I have a Django application. The database is Postgresql with 8GB size. We are also using Nginx with gunicorn. Will a 4GB server be enough for good performance ( like on Digital Ocean) ? I was under ...
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0answers
30 views

JDBC4/SQL or Hibernate/ORM?

I have an upcoming thesis project that may be used by the school itself if the system proves to be good. It is a web application (Struts2) for an Online Teacher's Performance Evaluation System. The ...
2
votes
4answers
470 views

Help understanding SQL Server 2005 execution plan

One of my stored procedure has long execution time (average around 4 to 7 minutes). Now I trying to tweak it an make it run faster. I am looking at execution plan and two things I see that using ...
7
votes
1answer
101 views

Is there a performance hit by breaking out tables into different schemas in SQL Server?

Is there any kind of performance hit when querying by placing tables in different schemas in SQL Server. For instance if I had 2 tables, Table1 and Table2, and put Table1 into the test schema and ...
0
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1answer
77 views

Large long-running reporting queries are causing very slow new mysql connections

Usually, mysql's connecton time is in the 0.001 second range. However, when I run a large reporting query (that spans multiple tables with aggregates), I get tons of warnings saying that new mysql ...
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0answers
14 views

Can MySQL Index Merge an Composite index with a single column index?

I am tuning a query and currently have an index as following : Index 1 : (col1, col2) An example query would be : SELECT * FROM t1 WHERE col1 = '1' AND col3 = '2'; I have created an index on ...
2
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1answer
116 views

SELECT query with DISTINCT on a table-structure for graphs is very slow

I have 2 tables where nodes contains about 60m rows and edges about 500m rows (both growing fast). These two tables represent a directed graph. CREATE TABLE edges ( node_from bigint NOT NULL, ...
4
votes
2answers
79 views

Using Database Engine Tuning Advisor in production

I have a SQL Server 2008R2 OLTP database which is experiencing performance issues during work hours. I would like to run Database Engine Tuning Advisor on this instance but I don't know how it will ...
1
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2answers
663 views

What is com_set_option?

As the title says, I'm wondering what is this command and why am I seeing a large amount of this query on my database? It's currently 13.30% of my total queries. I've tried googling this but there's ...
0
votes
1answer
71 views

Is my SQL Job causing the High Disk usage?

I have a concern regarding High Average disk queue length for one of my server with below configuration: Version: SQL 2005 with SP3, standard edition. windows: version 2003 r2 SP2 No Processors= 4 ...
1
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1answer
63 views

Best approach to get last value inserted

I have several devices that report via Edge network their position (and more data) to a UDP server which directly inserts this data in a SQL 2008 r2. I want to know which is the best approach to ...
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2answers
177 views

Improving a search query [closed]

I have a query for search function. Basically search function allowed user to define what they "have" and "want". Then this query will filter out all the possible result which created by other user. ...
3
votes
1answer
171 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 ...
0
votes
2answers
404 views

VARCHAR primary key - MySQL

Currently, I have a categories table with 2 columns - category VARCHAR(50) NOT NULL PRIMARY KEY and parent VARCHAR(50). The parent column is a foreign key (FK) to the category column. This seems like ...
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2answers
141 views

Security or performance risks using SQL CLR [closed]

Are there any particular security or performance risks in using the CLR in SQL Server ?
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0answers
46 views

Physical Table being used a Temp Table in a warehosue. Any advantage?

As I stated in previous posts I've inherited a warehouse based on SQL Server framework. In my continuous review of existing components and the practices adopted by the predecessors I found something ...
3
votes
2answers
287 views

Why is my CPU usage increase after setting database to read-only on SQL Server 2008 R2 [closed]

I administrate a reporting database. We run all the de-normalization process on a database DB1 daily, then we copy all the data to an another database DB2 on the same server which is queried by web ...
0
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0answers
106 views

Database design for price comparison site - too complex?

I'm working on a regular price comparison site with two exceptions. I want to show price history and also allow users to subscribe to a product with a specific size and color. As a result, I've ended ...
0
votes
1answer
67 views

Select Query takes more than a minute to retrieve data

I have a table that has 99 columns, all of them are not needed but they were there when we started. There is a Primary Key (Objectuid) which is a GUI and has the Clustered Index on the PK. The Table ...
1
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1answer
55 views

MySQL Latest Deadlock Explanation

Can someone explain this deadlock to me? It seems as if there are 2 inserts happening within milliseconds of each other with the same Primary Key. I'm not sure how this can cause a deadlock. At most a ...
0
votes
2answers
63 views

Does it make sense to order condition in where query?

We have a clustered index in table Tbl with order of A,B,C. Does it make senses to write a query to have WHERE A = @a, B = @b, C = @c or it'll be as same as WHERE C = @c, B = @b, A = @a Does the ...
0
votes
1answer
35 views

large SQL Performing quite slow (roughly 2 seconds for 290 rows) when having to deal with entries that can be NULL

SELECT version_stamp, pscdesc_id, psc, pscdesctext FROM pscdesc_history WHERE ( psc IN (SELECT psc FROM pso_history AS c ...
8
votes
1answer
2k 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 ...
0
votes
1answer
614 views

Amazon RDS CPU Usage keep increasing without any long running process in Show Processlist

We are using Amazon RDS(db.m2.2xlarge), CPU usage is suddenly increasing gradually even after we reboot the DB Server. This is happening just past 2 days and we didn't give any new build recently. I ...
13
votes
6answers
33k views

How to efficiently check EXISTS on multiple columns?

This is an issue I come up against periodically and have not yet found a good solution for. Supposing the following table structure CREATE TABLE T ( A INT PRIMARY KEY, B CHAR(1000) NULL, C ...
0
votes
3answers
55 views

SQL Server Compact - Will it perform well with heavier traffic sites? [closed]

I'm using Orchard CMS, and on initial setup, the default setting is to use SQL Server Compact. I'm not too knowledgeable about different database types and performance. So, will SQL Server Compact be ...
0
votes
2answers
29 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 ...
1
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1answer
46 views

Oracle performance loss from 10.1.0.2 to 10.2.0.5

I am testing an application on two database servers with the same data : 10.1.0.2 on Windows (for development) 10.2.0.5 on Solaris (for validation). We have a script which recreates a huge table ...
0
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1answer
46 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 ...
1
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1answer
68 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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0answers
31 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 ...
0
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2answers
58 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, ...