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

13
votes
10answers
1k views

What are the top 3 performance Issues that you encounter with your SQL Servers?

I am a student from Fontys University in Eindhoven, and I am currently carrying out a series of interviews to help with the development of a SQL Server tool and I would like to get feedback from the ...
2
votes
2answers
48 views

Filtering UNION ALL result is much slower than filtering each subquery

(edit: see end for a simpler example) I'm searching in a table named "cases" (135k rows, 29 columns). Some of the rows in this table have a type of parent-child relationship (of different types), ...
3
votes
1answer
51 views

Execution time with warm up cache

I have a query that takes around 1 second on first execution and 15-50 ms after running the same query again. The only difference between EXPLAIN outputs is that the second execution contains a lot of ...
0
votes
1answer
41 views

Same query same data different server different query plan

I have a query that hits a view, which references other views etc...several levels down. The query plan is a bit complex. I run the query on 2 different servers. On both servers, the number of rows ...
6
votes
2answers
145 views

Does table size matter?

I have a table like this (with more columns though): CREATE TABLE [dbo].[MyTable]( [SnapKey] [int] NOT NULL, [SnapDt] [smalldatetime] NOT NULL, [Company] [varchar](4) NOT NULL, ...
3
votes
1answer
55 views

Amazing improvement of script execution speed when split - not understood

I have an ETL job that merges data into about 20 columns of a fact table, all integer non-null (default 0) columns. There are 8 merge statements to completely update all the columns and they involve ...
0
votes
0answers
59 views

Suggestions for indexes or how to partition a table in SQL Server 2008R2

Table structure and DBMS SQL Server 2008 R2 I have a single table structure (flat) that has summarized sales data (YTD,MAT etc) by unique combinations of "Customer", "Product" and "Territory". ...
1
vote
1answer
33 views

SPID Change for a process?

On SQL Server 2012 can a process SPID change mid-operation? We have a very unique query that we've been monitoring (production, but controlled testing) and have seen it at different intervals with ...
4
votes
1answer
397 views

MS SQL high tempdb disk I/O during merge replication of BLOBs

Having a merge publication for replicating BLOBs (sql type - image), got very high tempdb disk I/O for my size of data. Publication is download-only and has no filters. High disk I/O is caused by ...
0
votes
2answers
24 views

Good reason to convert LONGTEXT column to smaller width if field is smaller?

We have a database that uses a LONGTEXT type for a column that does not need that much space. The maximum row size currently has about 6500 characters and that's with a few million inserts so it's ...
3
votes
0answers
47 views

LOB_DATA, slow table scans and some I/O questions

I have a rather big table with one of the columns being an XML data with an average size of XML entry being ~15 kilobytes. All other columns are regular ints, bigints, GUIDs etc. To have some concrete ...
0
votes
0answers
28 views

Want To Learn About MongoDB [on hold]

I am doing a little bit of research on MongoDB related to the following key points: (i) Experiment And Results (In which applications, MongoDB is used and what are the results) (ii) Threat To ...
2
votes
1answer
74 views

Improving mongodb read throughput for tiny database

I am given to understand that MongoDB will essentially perform like it is pulling records from memory if the working set is small. I wrote a simple MongoDB test program that inserts just one record ...
0
votes
0answers
20 views

problem with column oriented dbms features

I am currently looking for a free(or at least low cost) column oriented DBMS with really good compression abilities (at least 10:1 ratio) and fast response time. Having evaluated multiple open source ...
1
vote
1answer
700 views

Internal query on CDEF$ and CON$ very CPU bound

I am checking an application (Infor ERP LN) that loads a lot of data into an oracle 10.2 database. While checking one of the user sessions with SQL_TRACE and its output with tkprof, I found that the ...
0
votes
0answers
27 views

Sql Server Stored Procedure calling table-valued function - Performance

I'm using Sql Server 2012 and I have a stored procedure that does about 15 left joins and one of those joins is a CROSS APPLY to a table-valued function. The first 14 left joins are not gonna restrict ...
1
vote
2answers
31 views

Mysql Query Take Longer To Prcoess On My Dedicated Server Than My Local Server

One of my MySQL queries takes a very long time to process on my live server compared with my development server. My live server (Windows dedicated server) is more powerful than my local (development) ...
1
vote
2answers
45 views

Database logging optimization and maintenance in SQL Server

One of the Web applications I am working on, uses NLog to log debug and error context information in the database. Basically, it performs a moderate number of inserts (I appreciate some tens of ...
3
votes
1answer
509 views

What does “cleaning up” mean in MySQL InnoDB transaction status and how to prevent it?

In our database (MySQL 5.6.22 on RDS) we have a lot of transactions (~500) in a state "cleaning up" under the load: > SHOW ENGINE innodb STATUS; ... ------------ TRANSACTIONS ------------ ... ...
0
votes
1answer
99 views

Slow ranking values in MySQL

I have a table of around 30 million retail products, with various INT columns that describe sales counters and pricing at different retailers. I'm supposed to display well over 70 different rankings ...
2
votes
0answers
43 views

Clustered index on a fact table

I'm trying to work out what field(s) to use for the clustered index of my fact tables (which all have a similar structure). I'll use FactSales as an example: CREATE TABLE dbo.FactSales ( ...
3
votes
1answer
60 views

Finding hash match aggregate

After reading following blogs, I understand that hash match aggregate causes blocking. Using appropriate indexes it can be made as stream aggregate. Blocking/non-blocking aggregate operators The ...
0
votes
1answer
26 views

Storing mail in database, data type

I've found pretty poor informations about mail databases. My need is to archive mail messages downloaded from a normal pop3 or imap account: I am an ordinary user and I do not own the server, but ...
0
votes
3answers
490 views

Fastest way to do bulk import in MYSQL

I have got a question about the fastest way to copy a large number of records (around 10 million) from 1 table to another in MySQL. The target table has 1 primary key, 4 indexes and 3 foreign key ...
1
vote
1answer
125 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 ...
4
votes
2answers
185 views

SQL Server query on server taking longer than laptop

Our program uses an SQL server database as its back-end (SQL server 2008-r2 - 2014). The program is OK for performance but the Database seems to slow down a bit too much. As part of the nightly ...
2
votes
1answer
35 views

Possible causes that a MySQL/MariaDB query is slow under some table conditions

I am having a strange issue with a slow query under certain conditions: I have made a few tests and was able to isolate the issue to one single table called products_description (all the tables are ...
1
vote
0answers
38 views

SQL Server 2008R2 - BAK file backup performance issue

Just note I'm not a DBA or anything close to that. Problem: We are using SQL Server 2008 R2. We have 32 databases and backup to local disk (3PAR) using SQL Server maintenance plan. Normally it ...
10
votes
2answers
399 views

Minimizing Indexed Reads with Complex Criteria

I'm optimizing a Firebird 2.5 database of work tickets. They're stored in a table declared as such: CREATE TABLE TICKETS ( TICKET_ID id PRIMARY KEY, JOB_ID id, ACTION_ID id, STATUS str256 ...
3
votes
1answer
314 views

MySQL - Where can I find metrics on the performance of Blob vs file system?

I know and understand that there are performance hits in storing blob data in the database, but the blob portion of the data is going to be rarely retrieved/viewed, it is for smaller data (the vast ...
0
votes
0answers
34 views

Improving query performance involving similarity and full-text search

I have been trying to improving the performance of this query involving similarity and to_tsquery. I have a table (440,000 rows, PostgreSQL 9.5.2) with the following characteristics: test_db=> \d ...
2
votes
2answers
58 views

Filtered index error when using two column condition

I created a filtered index (in SQL Server 2012) and compared it with non-filtered index – I could see promising improvement as shown below. Now I need to change the filter condition to use two ...
9
votes
3answers
11k views

How do I best measure the query performance?

I have 2 stored procedures, where the second stored procedure is an improvement of the first one. I'm trying to measure by exactly how much that is an improvement. 1/ Measuring clock time doesn't ...
1
vote
1answer
87 views

Cursor Performance in New Server

I bought a new server with spec : HP ProLiant ML310e Gen8 v2 8 GB Single Memory, Intel Xeon E3-1220v3 3,1 GHz, 500 GB SATA 7.5K RPM, Windows Server 2012 R2 x64, SQL Server Standard 2014 x64, RAID 0 ...
0
votes
1answer
254 views

How to track IOPS statistics?

Is there a way to access statistics about IO operations per second in DB2 9.7? I am not interested in the buffer pool hit ratio, just IOPS.
0
votes
1answer
511 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 ...
3
votes
1answer
22 views

Performance schema: 'stage/sql/Sending data'

Background I am using MariaDB 10.0 but MySQL 5.6 answers are also of interest. Two machines cloned from the same image, same MariaDB configuration as far as I could tell, same dataset. One machine ...
0
votes
1answer
169 views

Application is hanging when database upgraded from SQL Server 2000 to SQL Server 2008 R2

Presently we are working with SQL Server 2000, the database is perfectly working with our software for retail sales counter application developed with VB 6.0. But after upgraded to SQL Server 2008 R2, ...
0
votes
0answers
40 views

MySQL: So many prepared statements in general log file

One of my clients complained serious performance issues in a web-application written in Java. I was suspecting that there might be some unoptimized queries which are causing the problem. I've enabled ...
0
votes
1answer
22 views

Speed benefits of Mysql Multiple Delete/Insert vs Select

I am working on a web application which involves a regular API call to the Amazon Product Advertising API. Given that Amazon limit the calls to one per second, I am looking at the fastest ways to ...
1
vote
1answer
61 views

Use of Trigger on table which can have 100 hits / second. Will it hamper performance?

Currently in one of our projects we have the following situation. The server computer is Windows Server 2008 Standard SP2. Processor is Xeon (R) 2.13 Ghz. We are running SQL Server 2008 R2. We need ...
0
votes
0answers
19 views

Performance Comparison using extended events

I am using SQL Server 2012. In my development database I have an old (MySP_Old) and new(MySP_New) versions of a stored procedure. This procedure has around 10 big queries in it. I need to compare each ...
2
votes
2answers
65 views

Filtering a result set on a very large table (using INCLUDE index in SQL Server)

Consider a very large table having hundreds of millions of rows defined as -- Here ObjectIdName and ObjectTypeName together are unique. -- Due to their size they aren't indexed, but rather they are ...
0
votes
1answer
60 views

Hashed and heap indexed object storage table insert and query performance

This question is partly to ask advice and assure this design is sane. I state the the desired properties upfront here, then go in more detail in the rationale and follow up with the design and example ...
0
votes
1answer
124 views

Query running slow on script and producing error 500 when run in phpmyadmin

I have a query that seems to take a good 30 seconds to execute even when the query produces no results. There are 4000 lines within the database and queries that produce all results run within ...
1
vote
0answers
20 views

MongoDB with multi core instance

I have a "large" EC2 instance with 2 cores running MongoDB as part of a Replicaset. Does MongoDB use both cores in parallel by default or do I need to make some configuration change?
17
votes
2answers
10k views

Configuring PostgreSQL for read performance

Our system write a lots of data (kind of Big Data system). The write performance is good enough for our needs but the read performance is really too slow. The primary key (constraint) structure is ...
1
vote
3answers
652 views

Oracle Compatible Parameter to set

Is there any difference in setting the Compatible Parameter to 11.2.0.0 vs 11.2.0.4 ? Are there any advantages / dis-advantages ?
1
vote
0answers
49 views

sys.dm_db_index_physical_stats slow on first run after rebuilding indexes

I have a 10GB database in SQL Server 2016 RC1 on Windows Server 2012 R2 where I just performed many insert and delete operations. Afterwards, I ran: EXEC sp_MSforeachtable @command1="SET ...
0
votes
2answers
167 views

Please recommend changes for my.cnf

I am not having any performance problems per se but want to improve my sites' performance if possible. Would appreciate any advice for how I can improve my.cnf. I have just one server, not ...