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

4
votes
1answer
69 views

Any potential issues/ DoS risks with frequent connections/ queries to a SQL Server db?

A database team suspects there may be an issue with a third-party ETL application opening, and closing, connections to a SQL server database repeatedly. In terms of exact numbers --- it opens about ...
0
votes
0answers
37 views

What is the fastest way to do a REGEXP find and Replace in MySQL database?

I have a table with 700,000 entries and I need to check each entry for 1,000,000 words and then replace the word if found from hello to #~hello~#. Words can occur multiple times in an entry and need ...
1
vote
0answers
296 views

iSeries Linked-Server SQL 2012 performance issue

I have a seen a serious performance dive when moving from SQL2008R2 to SQL2012 on my linked server queries. I have set the linked server on the SQL2012 server as a Microsoft OLE DB Provider for ODBC ...
1
vote
2answers
97 views

Partitioned Tables and Indexes - what are the downsides?

When talking about Partitioned Tables and Indexes for tables with less than 100 partitions, no nonaligned indexes: with that I mean: Nonaligned index An index partitioned ...
4
votes
2answers
214 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
70 views

Is there a Windows Performance Counter which contains the “Log Send Rate” for Availability Groups?

I wish to be able to get the "Log Send Rate kb/s", as per the SSMS AG dashboard (which is also available via log_send_rate column on the DMV sys.dm_hadr_database_replica_states) I'd like to get it as ...
0
votes
1answer
80 views

SET ANSI_NULLS - Performance of Stored Procedures

Does setting ANSI_NULLS ON/OFF affect the performance of stored procedures? SET ANSI_NULLS OFF GO SET QUOTED_IDENTIFIER ON GO CREATE PROCEDURE [dbo].[TestProcedure]
3
votes
1answer
174 views

Faster query with pattern-matching on multiple text fields

I have one Postgres table with more than 20M tuples: first_name | last_name | email ------------------------------------------- bat | man | batman@wayne.com arya | vidal | foo@...
2
votes
0answers
64 views

Postgres: CREATE INDEX, but very slowly, to reduce performance hit on rest of database?

I have a large production PostgreSQL (9.1) database running on Ubuntu Linux. It is currently being queried and used. However there is another use I need later, and I will need to create a large (...
3
votes
0answers
735 views

Slow inserts/updates into partitioned table with lot of partitions

I'm designing the partitioning for our new database, but we are facing performance issues in inserting or updating the partitioned table. For simplicity suppose we have one table T, which have an ...
0
votes
0answers
10 views

Reason of poor performance of ANSI joins in Oracle 9i

Please before flagging as duplicate, read the last paragraphs. In an Oracle 9i database this query runs in 0.18 seconds: select count(*) from dba_synonyms s,dba_objects t where s....
1
vote
0answers
117 views

MongoDB very poor query performance vs Oracle

I'm a MongoDB noob and trying to import data from an Oracle table. My Oracle table has 1 unique index on a single column, which is an id (a number - primary key). I successfuly imported data to ...
5
votes
2answers
140 views

Confused about why a particular index is being used

I have a table (with 170M rows) that looks as follows: CREATE TABLE [dbo].[Panel] ( [SubId] [varchar](15) NOT NULL, [LineageId] [int] NULL, [Buck] [varchar](20) NULL, [Lot] [varchar](...
0
votes
0answers
68 views

ORM and performance for SQL Servers

In a past SQLBits, one of the speakers went into some detail about ORM software's effect on SQL Server performance. The example the speaker was referring to was one in which the application was ...
1
vote
1answer
74 views

SQL Server - High Performance Record Comparison [closed]

Scenario : I have a collection of records to be inserted/updated into a table. Each record before getting inserted/updated in the table must be checked with the other rows in the table so as to find ...
1
vote
1answer
136 views

MIN, DATEADD, DATEPART, DATEDIFF functions cause table scan

A performance issue has been brought to my attention. It appears an application executes a query from time to time that takes nearly 3 minutes to execute successfully. The column is of data ...
5
votes
2answers
127 views

Joining two subqueries with union all and join leads to suboptimal execution plan

I've faced the similar problem on my production environment, but I managed to reproduce this behavior on Northwind DB. Consider the following query: USE NORTHWND; DECLARE @ids TABLE ( Id NCHAR(50) ...
1
vote
1answer
104 views

Measuring MongoDB I/O and CPU performance

I am new to MongoDB and I'm experiencing this NoSQL db through a series of very simple queries, with an Oracle exported data set. Aside measuring the execution time with primitives like db.system....
2
votes
0answers
52 views

Simple insert with Wait_Info = WRITELOG()

We have a query ( the same as some questions I made here ). a simple insert: INSERT INTO [My_Ttable]([IDChamada],[Evento], [Resposta],[IDTarifador],[ProximoEvento],[NomeDaMaquina],[DataMaquina]) ...
1
vote
1answer
172 views

CPU Time Slower in SQL Server 2014 than in SQL Server 2008 R2 [closed]

We’re upgrading a virtualized database server from an old SQL Server 2008 R2 Standard (vmware) to a new shiny SQL Server 2014 Standard server (hyper-v). We were doing some performance testing and to ...
2
votes
0answers
61 views

Query that can benefit from index, cluster or hash-cluster

I'm trying to find a equi-join query that shows a decent performance bump when I use an index, cluster or hash-cluster structure on my data. I initially need to run the query on unstructured data ...
2
votes
0answers
91 views

Every time I run a stored procedure it takes longer to complete until I restart the SQL Server [closed]

I need to optimize a critical stored procedure running on SQL Server 2012. The idea was to measure how long it normally took to run this procedure, make a few changes, measure the improvement and ...
0
votes
1answer
60 views

Is it possible to break down query time?

We have a setup of a few cloud servers that connect to a MySQL cluster on dedicated servers over Rackspace's Rack Connect network. We have noticed recently that the time for database queries (via PHP) ...
2
votes
1answer
199 views

CPU Time Slower in SQL Server 2014 than in SQL Server 2008

We’re upgrading a virtualized database server from an old SQL Server 2008 R2 Standard (vmware) to a new shiny SQL Server 2014 Standard server (hyper-v). We were doing some performance testing and to ...
0
votes
0answers
39 views

Non-structured Query performs better than on clustered, hash-clustered and indexed?

I am using the following query as a base line on some unstructured data (no indexes, no clusters etc) and the query is performing better on the unstrutured data than when I add indexes to the join ...
8
votes
3answers
187 views

Poor cardinality estimate disqualifies INSERT from minimal logging?

Why is the second INSERT statement ~5x slower than the first? From the amount of log data generated, I think that the second is not qualifying for minimal logging. However, the documentation in the ...
0
votes
1answer
126 views

Slow mysql query full text search tag database

In the database are ~700k images. Each image has its own tag(s). I want to be able to search images by the tags with a full text search query. The query does exactly what I want but it's very slow. ...
2
votes
1answer
37 views

Excluding rows by lots of ids

I need to exclude some rows that the user has already seen. Currently I am doing this by simply comparing the ids that the user has seen to the row's ids by running this query (there are also other ...
1
vote
0answers
195 views

Two servers with the same exact specs taking way different times to run the same query

I have 2 servers with the same exact specs: Test Server and Production Server The same exact database with the same exact data is on both of these servers. I remote into each server using remote ...
0
votes
0answers
35 views

Query performance tuning with joins on views with large data

I've this query in oracle. This is basically the query of a BA report which I'm trying to tune. SELECT DIM_PROJECT_OL.PROGRAM_ID, DIM_ANALYTIC_STRUCT_ACCOUNT_OL.STRUCTURE_ID, SUM(NVL(...
0
votes
1answer
123 views

How to profile trigger database performance impact

I want to set up some triggers on a DB2 box (LUW, 9.7). The DBAs are concerned that if the trigger fires too often, it will adversely affect general performance. What's a reasonable cheap approach ...
1
vote
0answers
48 views

Identify a blocking process in MongoDB

I have a single MongoDB instance is performing quite badly. I noticed that db.currentOP().inprog.length quite often becomes quite big, sometimes even goes up to 100. When I drill down to the actual ...
2
votes
1answer
94 views

Computational power required for this query

I am not sure if the query I am trying to run is unreasonably large, in terms of computational power. The query will identify islands (and their duration) of a certain condition in my db. Things work ...
4
votes
1answer
644 views

Should I use UUID as well as ID

I've been using UUIDs in my systems for a while now for a variety of reasons ranging from logging to delayed correlation. The formats I used changed as I became less naive from: VARCHAR(255) ...
3
votes
0answers
53 views

Isolate database performance on an instance

I have SQL Server 2014 Standard Edition installed on a machine with two different users and two catalogs, each of them accessed by a different user (each user is strictly tied to his catalog). Is it ...
6
votes
4answers
482 views

How can I Debug a Buffer Issue?

I have a production "Microsoft SQL Server 2012 (SP1) - 11.0.3128.0 (X64)" that is showing weird buffer and page life expectancy (PLE) symptoms. I am running this every minute on my server (to track ...
2
votes
2answers
103 views

Nested table hierarchy: foreign key duplication vs. join

I have a nested table hierarchy, similar to the following one (this is an example but demonstrates the schema well enough): +---------+ +---------+ +---------+ +-------------+ | users | | ...
2
votes
1answer
374 views

What is the best index implementation for a really large databse

I have a really large SQL SERVER table with only non clustered indices for several columns , while querying the table the execution plan shows RID Lookups , i expected to see this kind of lookup ...
6
votes
1answer
196 views

Performance problem after migration from SQL Server 2005 to 2012 [closed]

Last Friday, I migrated a SQL Server instance from 2005 Enterprise Edition to a brand new Windows Server 2012 server with SQL Server 2012 Enterprise Edition installed. Since then, users have started ...
0
votes
1answer
225 views

Database-design for a small filter / search tag function

I'm building a search function in php for a database with 1k to 4k articles. It's going to be built on a tag system. I've been reading some tutorials, blog posts, q&a etc about it. Most important ...
2
votes
1answer
106 views

Understanding performance of highly unique WHERE clauses

I've been struggling to understand how to deal with a specific type of performance issue that shows up very often in this scenario: when you are wanting to apply multiple filters in a query, but you ...
-6
votes
1answer
36 views

Changing numbers in a where clause on the same SQL can it make faster or slower [closed]

I just received a question from one of the developers and the question is, he ran a SQL statement with a where clause and when he puts 004 the SQL finished very fast, and on the same SQL when he puts ...
0
votes
1answer
165 views

Convert UNION query to JOIN. Is it actually needed for high performance?

I have the following table structure in MySql. To get the list of roles for a particular user, I use the following union Query, SELECT r.ID, r.ROLE_NAME, r.TENANT_DOMAIN, r.PROVIDER_ID FROM `...
1
vote
0answers
72 views

Postgres search and replace

What is the difference between the search in search and replace, (the replace function) and full text search (tsvector) in Postgres? Or, put another way, can tsvector be used in search and replace (...
1
vote
0answers
41 views

SQL Server on big machine falls over inexplicably

We've been doing some throughput testing with our web application. The production application resides on a couple of machines in the amazon cloud, consisting of a web server and a database server. ...
2
votes
2answers
96 views

MariaDB server with 80K-100K DataBases

BACKGROUND : We have an environment where there is a new DB created almost every minute and it will be Dropped after few days or weeks (maximum 1 month) such that the space used is about 300GB~400GB ...
4
votes
0answers
171 views

How can we improve this PIVOT operation? ( SQL Server 2008 R2 )

We have this query, that runs in 1:10. We need to improve this. This is just a test query, but we will implement this upgrade on our real query. select top 100 * from ( select codCliente ,...
5
votes
1answer
416 views

Slow fulltext search for terms with high occurence

I have a table that contains data that is extracted from text documents. The data is stored in a column called "CONTENT" for which I have created this index using GIN: CREATE INDEX "File_contentIndex"...
0
votes
0answers
111 views

How come MySQL LIKE is faster then FULLTEXT?

So, I was trying to optimize my MySQL queries, but found out that i'm actually doing this wrong. I've changed my query from using SELECT * FROM test WHERE tst_title LIKE '1%' To: SELECT * FROM `...
1
vote
2answers
81 views

Duplicate Same Table for Multiple locations

We have an "appointments" table with following schema. appointments(app_id,.....,app_type,location_id) app_type - type of appointment location_id - keeping the location for multiple location setup. ...