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.

learn more… | top users | synonyms

0
votes
0answers
35 views

General error: 1615 Prepared statement needs to be re-prepared

I have been running into this issue every time I try and sync a medium size JSON object to my database so we can perform some reporting on it. From looking into what can cause it I have come across ...
1
vote
1answer
111 views

Execution plan index suggestion - difference between similar queries

I am trying to analyze queries on this table: CREATE TABLE [dbo].[Values]( [tid] [smallint] NOT NULL, [t] [datetime2](3) NOT NULL, [v] [real] NOT NULL, CONSTRAINT [PK_Values_Unique] ...
2
votes
0answers
28 views

longitude lattitude performance

I have to store frequently (at least every min) the position (longitude, latitude) of animals in a DB, and perform for each update a search in order to determinate if ananother animal is near to it. ...
0
votes
1answer
85 views

What is the fastest way to clone/copy oracle databases on the same machine?

I want to clone oracle 11g databases on the same machine and I need to change user etc. from e.g. PROD to DEV. For that I use expdp/impdp, but this tends to be slow with increasing database size. I ...
0
votes
0answers
17 views

Joining 2 big tables turn into a server down problem

Recently I was using a database (MySQL with Workbench) in the company that I work for (I'm a business analyst, not a DBA), and wrongly I created a query joining 2 tables that basically are the same. ...
1
vote
0answers
18 views

What is the fastest way to clone/copy oracle databases on the same machine?

I want to clone oracle databases on the same machine and I need to change user etc. from e.g. PROD to DEV. For that I use expdp/impdp, but this tends to be slow with increasing database size. I need ...
0
votes
0answers
47 views

Why would call to scalar function inside a Table Value Function be slower than outside the TVF?

I am writing a Table Value Function, calling the function takes 10x as long as directly running the code. I traced this to a call to a multi-line scalar function inside the TVF. The call to the ...
2
votes
1answer
85 views

What is running on my server every night?

My data disk queue is high every night at about 1:00 AM UTC. I did sql profiler trace and found that there are many queries running at the same time similar to these: Can someone tell me what is ...
1
vote
1answer
33 views

Print, transaction and cursor performance in Transact-sql

I'm having some performance issues when I run a script. I was reading about the problem with print and its performance, but I cannot figure out how to reduce the impact. The algorithm is O(n^2). The ...
2
votes
2answers
45 views

Does the system process slow down my Database access?

I have a Fairly large DB containing mostly html documents. I wrote a python script that fetches always 1000 html documents at once from my database cur.execute("SELECT id,url,html_file FROM html ORDER ...
0
votes
0answers
22 views

How to figure out how to split a table using the proper scheme

If you have a big table that you want to partition and you have 2 candidates as the partitioning key (in the sense that 50% of the queries use one column and 50% of the queries use the other column ...
3
votes
1answer
248 views

Optimizing large database query (25+ million rows, using max() and GROUP BY)

I'm using Postgres 9.3.5 and I have a large table in the database, currently it has over 25 million rows and it tends to get even larger rapidly. I'm trying to select specific rows (all unit_ids with ...
2
votes
1answer
47 views

Which database technologies to consider for a data search application?

I'm designing an application that only does read queries to some database tables (it's a kind of search application); the queried data is updated at night by the system (so speed is less critical, ...
0
votes
1answer
35 views

MySQL/MariaDB Limitations

we're running MariaDB on our DB server. We have to install multiple databases on each DB instance (in fact each DB server runs multiple MariaDB instances) because each database must be separated. ...
0
votes
0answers
22 views

Mysql performance tunning [closed]

I have 2 VM : one x.x.x.22 "16G RAM" and "Intel(R) Xeon(R) CPU E5620 @ 2.40GHz 8Core " and one x.x.x.21 "8G RAM" and "Intel(R) Xeon(R) CPU E5620 @ 2.40GHz 8core" Now , app is installed ...
0
votes
0answers
52 views

is this dead simple query too slow?

I have added and removed a few indexes from my user table and, while testing, didn't see the performance gains I had hoped. As a result, I removed the indexes and tried a simple query to see what my ...
3
votes
1answer
281 views

Is there any performance difference in using a unique index on primary key?

I know there are lost of similar questions to this one, but none that really answers this: Is there ANY difference in performance in using an unique index in a primary key, using a MyISAM table on a ...
7
votes
1answer
124 views

Lower performance on newest servers

We have several db servers on production, 4 of them with very similar hardware configuration. Dell PowerEdge R620, only difference is that 2 newest ones (bought and configured 3 months ago) have RAID ...
0
votes
1answer
82 views

How to increase sql server performance? denormalization (making cascade delete off) vs making duplicate data

I have a database with following related table ( sql server enterptise edtion 2014) each state have many citites which each city has may municpalArea and so on State => Cities = > ...
1
vote
1answer
80 views

Calculating a running balance to store with transactions

I need to put a read-only copy of balance and transaction data from a legacy system, which will only be used to view/print statements. Balance | id | member_id | product_id | balance | | 1 | ...
2
votes
1answer
78 views

MySQL CPU & Memory Spikes

Every couple of days, my server's CPU and memory usage spikes up to 100%, making our vBulletin forum almost unusable for 5-10 minutes. CPU is typically at 1-2, Memory at 3GB. During the spikes, CPU ...
0
votes
1answer
71 views

Is normalization advisable on transactional data?

I have read a lot of articles about normalized vs denormalized schemas, but I find very little mention of the cost of row insertion. I am considering the impact of converting a 100% denormalized ...
0
votes
1answer
21 views

Stored Procedure Performance Issue in Sharepoint Report

We have a report stored procedure that runs in about 1 minute in production; however, when executed from the Sharepoint it populates, it rus for over 20 minutes, with exactly the same parameters. ...
0
votes
0answers
14 views

RAID configuration for mysql [closed]

I attached 4 10G disks to mysql Server and I used RAID 0 but still same mysql performance the same, Do I have to change configuration in my.cnf to let mysql know about RAID 0
1
vote
2answers
150 views

RAID configuration for mysql

I attached 4 10G disks to mysql Server and I used RAID 0 but still same mysql performance the same, Do I have to change configuration in my.cnf to let mysql know about RAID 0. this is my mount ...
0
votes
1answer
59 views

What's faster: two UPDATEs with WHERE (in / not in) or one UPDATE with CASE?

What's best performance wise, two separate UPDATEs: UPDATE table1 SET enabled = 0 WHERE code NOT IN ( SELECT id FROM table2 ); UPDATE table1 SET enabled = 1 WHERE ...
8
votes
2answers
269 views

Why are simple SELECTs on InnoDB 100x slower than on MyISAM?

I have quite an annoying problem. I want to use INNODB as my main database engine and give up on MyISAM as I need the former for using galera-cluster for redundancy. I copied (description follows) ...
1
vote
2answers
89 views

How do I maintain high INSERT-performance on PostgreSQL

I'm working on a project which is parsing data from measurement files into a Posgres 9.3.5 database. At the core is a table (partitioned by month) which contains a row for each measurement point: ...
3
votes
1answer
128 views

Why does my query end up with two seeks instead of one and how do I fix that?

I have these two tables: CREATE TABLE [TaskItems] ( [ItemId] UNIQUEIDENTIFIER NOT NULL UNIQUE PRIMARY KEY, [LastOperationTime] DATETIME NULL DEFAULT GETUTCDATE(), [OwnerId] ...
1
vote
2answers
78 views

Changing compatibility level of database causes performance improvement of stored procedure

We have a Web Application in a Windows Server 2012 Datacenter (IIS 8), running under .NET Framework 4.0, which connects to another Windows Server 2012 Datacenter with SQL Server 2012. My Database has ...
2
votes
1answer
41 views

Innodb DB Consuming IO even when no operations are being done

I am currently doing some stress testing where I am pushing inserts to the database as fast as I can. The simulation inserts 10000 records per second. After inserting around 200 million records I ...
0
votes
1answer
44 views

Optimal way of loading, registering, indexing and querying a huge XMLDB

I've got 35 million highly structured XML documents, with a total size of 500 GB. An XSD is available for this data, and the end goal is to transform the data into an RDB. All fields can be considered ...
0
votes
0answers
44 views

MySQL DATE vs DATETIME read/write performace

Did anyone perform accurate read/write performance comparisons of MySQL's DATE vs DATETIME column types? Please do not bother writing "It should be faster" or "I think it's faster". I am looking for ...
0
votes
1answer
74 views

Multi-Column Full Text Search Going Very Slow

I have a full text index on a table articles for the columns content, title and keywords When doing the search on each of the columns, like so select count(1) from articles where ...
6
votes
1answer
178 views

Huge differences of performance of MySQL in two servers

We have a MySQL server installed in two different machines, a testing server and a production server, both windows, which is used by a web application. The problem is that there are HUGE performance ...
2
votes
0answers
33 views

Sample a Mysql table to increase performance

we are storing all our clients traffic data in a MySQL 5.1.73 database (MyISAM) and then we use it to generate user and internal statistics/graphs, always searchinng for a client id and a date/hour. ...
0
votes
0answers
34 views

What is “good” single-block read latency?

Is there a reference anywhere that I can go and see what kind of single-block read latency I can expect from Oracle given a certain hardware configuration? I can run a query to show the current ...
0
votes
0answers
23 views

Optimal layout strategies for Time-Series using Columnar storage

In the context of time-series and specifically columnar storage systems. Question: What are the processes or heuristics that are used to determine how best the columns of contiguous values be grouped ...
0
votes
0answers
15 views

MySQL: What are the pros and cons of running with engine=Memory vs on a memory-mapped filesystem?

What is the difference (in terms of read and write perf, alter tables, backup and recoverability and consistency) of running a MySQL database on a memory-mapped filesystem vs with ENGINE=MEMORY
0
votes
0answers
20 views

Which benchmark assess string pattern matching in a database?

I have a postgresql DB in which I do a lot of string matching ala : UPDATE table1 SET colum1 = TRUE WHERE colum2 LIKE '%teststring%'; colum2 is a whole html file As I said I do A LOT of this and ...
0
votes
1answer
48 views

creating a 24 hours data table - Suggestions/improvements

I am planing to have a table to store the data based on every hour , in short I have a file with 24 hour data and I need to use this to populate a hourly bar/line graph. Below is a sample 24hr data ...
1
vote
0answers
24 views

Troubleshoot of WRITELOG on new machine running very slow? [closed]

I recently moved away from an old Intel 2,4 GHZ Dual Core dev. machine with 4 GB RAM and SSD to a XEON 2.8 GHZ, 8 GB SSD machine Both machines running Win 7 pro. My trouble is that this new machine ...
2
votes
1answer
173 views

Finding reason behind high write IOPS on MySQL (RDS) server

I am having performance issues with an AWS RDS instance (running MySQL 5.6). This is the backend db to an XMPP server called Tigase. According to Tigase Inc. this type of db instance should be able ...
0
votes
1answer
48 views

If a query contains two identical subqueries, will they both run?

Say I have a SELECT query that contains two identical subqueries, like the below: SELECT (SELECT SUM(Price) FROM Product p WHERE p.GroupID = g.GroupID) AS 'TotalCost', (SELECT SUM(Price) ...
1
vote
1answer
27 views

Optimizing bulk update performance in Postgresql with dependencies

Basically my question is the same as this one, but WITH dependencies, so drop/renaming the table is not a trivial option (I assume). We are refactoring a large, poorly designed table which has many ...
0
votes
0answers
37 views

How do triggers work on partitioned tables?

I have partitioned a table on the basis of a column. This column can either have 0 or 1. So, only two partitions (p0, p1) have been created internally. On this table there are 3 triggers which execute ...
0
votes
0answers
27 views

Performance implications of mixing VARCHAR and CHAR fields in MySQL Table

I read the following answers in this forum: What is the performance impact of using CHAR vs VARCHAR on a fixed-size field? MySQL: Does the order of the fields in a table make a difference in ...
3
votes
2answers
220 views

Can I update every datetime in bulk?

The current database assumes all times are local to the user. Now we're changing this so the database stores everything in UTC and our application converts the UTC time in the database to the correct ...
2
votes
1answer
85 views

If an INNER JOIN in a query returns no rows, do additional INNER JOINS add a significant performance overhead?

If I make a query as follows: SELECT * FROM TableA A INNER JOIN TableB B ON A.AID = B.AID INNER JOIN TableC C ON B.BID = C.BID Does the INNER JOIN with TableC add significantly to the performance ...
1
vote
2answers
199 views

MySQL performance problem using indexed datetime column

I tried to solve the following problem for about one hour now and still didn't get any further with it. Okay, I have a table (MyISAM): ...