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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4
votes
2answers
408 views

Is an SQL Server trace 'considered harmful' in production?

Context: Careful DBAs We've been bought out a few times and our latest overlords have DBAs who keep carefully guard their production database servers. Overall this is good. However, we have run ...
0
votes
0answers
14 views

Write operations on the RDS Mysql Database becomes Slow during long run load test [on hold]

I'm having serious performance problems with MySQL and the InnoDB engine in long run load test. Even the simplest table makes writing operations.I'm using Amazon RDS m3.xlarge instance for performance ...
2
votes
1answer
47 views

Ways to Reduce Database Size and possibly improve performace. Untouched enviroment.

I am new to an environment. The Databases are virtually untouched by a seasoned DBA. I am looking for ways to reduce DB size and possibly improve performance. Unfortunately, I only have WEb edition ...
1
vote
1answer
14 views

Address Windowing Extensions Overhead

I just found another SQL Server (2008r2) with AWE enabled on a 64-bit OS/SQL combination. Has anyone done an research as to the overhead created by enabling AWE on the 64-bit OS/SQL combination? It ...
5
votes
1answer
51 views

Find rows where integer sequence contains a given subsequence

Problem Note: I refer to the mathematical sequences, not the sequences mechanism of PostgreSQL. I have a table representing sequences of integers. The definition are: CREATE TABLE sequences ( id ...
2
votes
0answers
19 views

SQL Server 2014 vs Amazon Redshift performance [on hold]

I have heard the SQL Server 2014 using clustered columnstore indexes is second only to HANA in performance. Does anyone have any metrics that compare RedShift to SQL Server 2014 for query performance ...
1
vote
0answers
21 views

Single Redshift table vs several mysql/ pgsql (on RDS) tables for small (200 tables * 20 columns * 1 million) monthly aggregation data

We're providing SaaS Data Analytics Dashboard for around 200 clients. We're using Amazon Redshift for storing data in in around 5 tables. We're getting around 30 million hits per day. Currently our ...
0
votes
0answers
28 views

Tuning MySQL with InnoDB engine for my application

I've read through a lot of answers, and I realize this is mostly application specific, so I wanted to give some background as to what I'm doing with the database and hopefully get some tips on tuning ...
0
votes
0answers
17 views

Informix performing slow - Query is around joining 10+ tables and spanning 70 lines [on hold]

At work, we have an Informix database server, managing our data. We have multiple queries spanning 70 lines and accessing 10+ tables using a join. The query takes approximately 4s to return. All the ...
4
votes
1answer
40 views

Fast alternative for “NOT IN”

I have a table A that got a field called id that is the primary key of this table. I also have a table called B which also have a field called id as primary key. Now I want to get all rows from ...
0
votes
0answers
27 views

optimizing a wild card search query in mysql

I want to have a search option in my game portal site. (right now i'm using google's in site search) I want a user to search to enter a search term and need my query to search the search term in the ...
0
votes
1answer
59 views

Multi-threaded inserts vs serial

I have a large database application on SQL Server 2012 Standard Edition which receives data from hardware in chunks of 500-1000 (100 byte) rows every few seconds through a stored procedure. Would a ...
0
votes
1answer
33 views

Custom big key-value database indexing [closed]

I want to make a key/value database with millions of records. A custom-length unique UTF-8 text will be used as key 16 unique bytes will be used as value What is the best way of storing this ...
12
votes
1answer
869 views

Best way to write SQL Query that checks a column for non-NULL value or NULL

I have a SP with a parameter that has NULL as default value and then I want to do a query like this: SELECT ... FROM ... WHERE a.Blah = @Blah AND (a.VersionId = @VersionId OR (@VersionId IS NULL AND ...
0
votes
0answers
35 views

Improving SELECT queries involving multiple joins

I have the following query: SELECT event.* FROM event LEFT OUTER JOIN invalid ON invalid.event_id LIKE event.id AND invalid.userid LIKE '<userID>' LEFT OUTER JOIN owner ON owner.id ...
2
votes
1answer
50 views

MySQL (MariaDB - 10.0.16-MariaDB-1 (Debian) strange performance issues

I am running version 10.0.16-MariaDB-1 (Debian GNU/Linux 8.1 (jessie)) on Dual Xeon CPU, total 32 cores with 128 GB of RAM. This is a dedicated DB server and has been recently migrated over from ...
0
votes
1answer
36 views

Cache statistic data in SQL Server

Currently my team develop additional web app to let customers analyze user statistics to theirs portals. So we have a table with all logins. It contains about 100 millions of rows. One user could ...
1
vote
0answers
23 views

How to best distinguish between “types” of missing data?

I am working on large tables (> 100 fields each) currently organized in flat-files in csv-format. An Oracle DB is to be created to store all the data and allow for several more or less intricate ...
1
vote
2answers
182 views

What is the best way to purge data from a table with minimum damage to performance?

When you purge records from a database table, deleting them, you have impact on the logical and physical structure of the target table, as well as indexes and statistics. What maintenance should be ...
0
votes
2answers
20 views

Separate indices for the field I want to get the MAX() and the ones in the WHERE clause

My customer's database has a gigantic table (hundreds of millions of records) and a SELECT that, by cumulative use, is eating a huge chunk of processing time. Each exec takes almost a minute in ...
1
vote
1answer
15 views

Postgres or MapReduce to Match Reciprocal Needle Pairs from a Stack of Needles?

I have a Postgres (latest version) table with about a million lines (a_lat, a_lon, b_lat, b_lon) that each have about a dozen criteria. These lines go together in reciprocal pairs (A - B, B - A), ...
13
votes
2answers
96 views

Index on a persisted computed column not seekable?

I have table, called Address, that has a persisted computed column called Hashkey. The column is deterministic but not precise. It has a unique index on it that is not seekable. If I run this query, ...
2
votes
1answer
59 views

why update a table take so long on oracle

I have a table A which has 3800+ rows, another table B with 300+ rows. when I execute a update like this: update A set some_colum = '2' where another_column not in (select id from B) it takes 33 ...
2
votes
1answer
69 views

Why is ORDER BY LIMIT 1 so much faster than MAX?

Here are my two queries: select sts_in from sta_session where sts_user_id=2006 AND sts_sessid!='0jitkt80gg3avere03tqk4lhi6' order by sts_in desc limit 1; And select max(sts_in) from ...
3
votes
3answers
196 views

Do I want an index if all I care to query is field not null

In SQL, do all the common considerations about indexes apply if everything I'll ever want to query (in the where condition) is when a field is not null? Is there a special configuration of the index ...
2
votes
3answers
138 views

SQL Server Slowdown?

We're a small shop, and I'm certainly not a DBA by any stretch of the imagination, but I've recently inherited a somewhat large older database (been running since at least 04), that in the past month ...
0
votes
2answers
54 views

Multiple WHERE IN on multiple columns

I am not very experienced with sql queries and looking for an efficient way to perform the same WHERE IN condition on multiple columns. More specifically, i'm doing the following: SELECT a, b FROM ...
0
votes
1answer
27 views

Does PostgreSQL benefit from more cores or faster cores for READ heavy applications? [closed]

I have been trying to figure out how to go about configuration of a PostgreSQL instance that will have 64GB ram (which is far larger than the database) and if I should opt for more cores or faster ...
6
votes
2answers
153 views

Optimizing WHERE condition for TIMESTAMP field in MySQL SELECT statement

I am working on a schema for an analytics system which tracks usage times, and there is a need to see total usage time in a certain date range. To give a simple example, this type of query would be ...
0
votes
0answers
21 views

Data transfer in sql server 2008

I have following requirement In SQL server 2008,Trying to implement in stored procedure source table T with 100000 records need to be insert into destination table T1.A Job will be schedule for this ...
2
votes
2answers
39 views

SOS_Scheduler_Yield wait type

I am having a process that has a last_wait_type as SOS_Scheduler_Yield and is inserting 100 records to a table. This process has been with this wait type forever with low CPU utilization %. There are ...
0
votes
0answers
53 views

Oracle Performance on 2 servers

I have the same database on two different servers(production and test) with major differences in query time as follows: Query1: SELECT distinct dms_get_FAST_serverpath(d.id) full_name FROM ...
3
votes
1answer
50 views

Why does it take so long for Postgres to return a sequence number?

I have an application that does bulk loads into a large table (100 million rows). I am using Postgres' COPY FROM functionality to load data from a flat file. The target table has a primary key of id. ...
2
votes
1answer
44 views

How to make a query using “where MONTH(datetime)” faster?

I already tried to add an index on the datetime column, but the result is still unacceptably slow. SELECT s.id, s.player, COUNT(case when dg.winner = 1 AND dp.colour <= 5 then 1 when dg.winner = 2 ...
3
votes
2answers
50 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 ...
2
votes
1answer
117 views

Excessive CPU use in vendor SQL Server DB

Background: I've got a SQL Server 2012 DB provided by a vendor so modification of queries and tables is limited. We do own the DB though, so we can add and maintain indexes. Indexes haven't been ...
0
votes
2answers
65 views

Managing tables in database

I am new to web development field and particularly very poor at database management. I am developing a web application which resembles Project Management System where new companies can add their ...
3
votes
0answers
46 views

How to do Statistics in Partial Indexes of PostgreSQL efficiently?

This answer motivated think again my following tables but I am still uncertain how to store statistic data for quick selection. I think it is well done with partial indexes because only a subset of ...
1
vote
1answer
44 views

Update records from one table to another in different databases where condition is accomplish

I have two tables stored in two differents DBs and I need to perform some sync between both tables based on lastmodifieddate and lastSyncAt. Let's call them as db1 and db2. This is the DDL schema for ...
2
votes
1answer
50 views

What is limiting the batch requests per sec

We have a newly created azure sql server 2014 instance. The specs for the server are as follows Pretty bare bones I know. Since this is just a testing server, we have opted to set up the data files ...
1
vote
0answers
41 views

Measure SQL Azure Transaction Rate

We are on SQL Azure v12 Standard/S2 Service Tier and are not satisfied with the performance so I am trying to measure where the bottleneck is. I realize that we could be hitting the limits of the S2 ...
1
vote
1answer
32 views

How to write marker messages into the MySQL general_log?

I'm build a performance testing harness for our distributed web app. I'm using JMeter to drive it by simulating poorly performing parts of the app from the web side. I've set up MySQL to log to the ...
2
votes
0answers
84 views

Transaction log bloat when writing to table on replicated database with parameterized filter

We are observing abnormally large log writes whenever we update a table that is used for parameterized filter in a merge replication. There are a number of join filters as well. When executing a ...
1
vote
1answer
83 views

What is the best option to easily fix fragmented heap indexes?

I have SQL Server 2008 R2 SP2 and also SQL Server 2012 SP2 on these servers. I have a database in which there is a lot of heap indexes which are more than 90% fragmented. What is the best option ...
2
votes
0answers
72 views

No significant performance increase after migrating from SQL Server 2005 32bit 4 Cores 4 GB RAM to SQL Server 2012 64bit 4 Cores 32 GB RAM [closed]

We run regularly a series of data analysis scripts on one of our databases. The MDF File of the database is several gigabytes big, the scripts perform not only selects, but also inserts, updates and ...
4
votes
0answers
66 views

Which to trust?

We are troubleshooting a long-running issue with a vendor. Their software has a tendency to freeze up and stop working once or twice a week causing major disruptions to our operation. They have been ...
0
votes
1answer
35 views

Best approach to compare specific columns of 2 tables in different databases?

I'm running an application who does have a shorten version of a table in the backend database. Both application- and backend-tables are having the same primary keys and some specific key columns. ...
0
votes
2answers
76 views

How can i update my database from another database using temporary tables?

I want to update tables of my database using another big database every day with using temporary tables and without returning result. How can i update it? This my temporary table : use data_pro; ...
1
vote
1answer
30 views

MySQL Read/Write Benchmark

I'm trying to benchmark Read/Write speed in MySQL 5.5. Currently I have a stored procedure that insert rows with random numbers to a table and I'm measuring time of execution before and after ...
4
votes
0answers
125 views

Why is my Azure SQL Server so slow?

We currently have a VM that is very underpowered and are proposing to move to an Azure VM with better specs. The problem is, the Azure VM is much slower than the original VM even though it is of a ...