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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0
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1answer
996 views

How to configure my.cnf for Mysql 5.1, which is using too much CPU?

I am new Database engineer. I am having trouble in my server which is using too much CPU on database query(simple count statement). I have googled about it, so i found out it depends on system ...
0
votes
3answers
233 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 ...
4
votes
2answers
391 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
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0answers
12 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
50 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 ...
1
vote
2answers
287 views

SQL 2008 Server - performance loss possibly connected with a very large table

We have SQL Server 2008 with 3 active databases running on it. DB1 - cca 400 MB size DB2 - cca 8 GB size DB3 - cca 42 GB size - but the majority of records are not used at all In DB2 we have a ...
2
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0answers
16 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
20 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
27 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
1answer
123 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 ...
0
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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
38 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 ...
1
vote
2answers
392 views

Mysql improve Self join performance large table?

I have a task to help identify conflicting IP ranges , I want to highlight when one companies IP range falls within another's ... below is the sample table, I have converted the IP ranges from .dot ...
6
votes
1answer
266 views

Timestamp-based index

I have a big database (200GB+) that contains some log info. And I want to speed up SELECT queries and stored procedures. I have a table with a GeneratedOnUtc datetime column, and have a non-clustered ...
0
votes
1answer
177 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 ...
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 ...
2
votes
2answers
2k views

Improve MySQL Query Performance - Too many records

I am using MySQL RDMS for a contact management system. Now a days my database grew in size and contains more than 1 million records. Checking duplicate phone numbers became a big issue during ...
0
votes
1answer
57 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 ...
2
votes
1answer
335 views

Database design for a table with both bulk insert and single row insert

I have to design a table where records will be inserted in two ways. Bulk insert from a batch process from a delimited text file between 2 - 3 million rows in a short burst. Later the same records ...
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 ...
86
votes
7answers
80k views

How can I optimize a mysqldump of a large database?

I have a symfony application with an InnoDB database that is ~2GB with 57 tables. The majority of the size of the database resides in a single table (~1.2GB). I am currently using mysqldump to ...
1
vote
1answer
164 views

MongoDB Insert Performance

I have some data which are aggregated in chunks and later pushed into another collection. The problem is that aggregated data pushing to another collection is very slow and takes from few hours and i ...
12
votes
1answer
863 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 ...
26
votes
5answers
19k views

Index Seek vs Index Scan

Looking at an execution plan of a slow running query and I noticed that some of the nodes are index seek and some of them are index scan. What is the difference between and index seek and an index ...
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 ...
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 ...
10
votes
2answers
15k views

What is the fastest way to insert large numbers of rows?

I have a database where I load files into a staging table, from this staging table i have 1-2 joins to resolve some foreign keys and then insert this rows into the final table (which has one partition ...
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 ...
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 ...
13
votes
2answers
94 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
2answers
3k views

MySQL / InnoDB: Does daily optimization improve performance?

Would performing daily optimizations of tables increase performance for MySQL and InnoDB? I have never did this before, but I have seen this module for Drupal http://drupal.org/project/db_maintenance, ...
2
votes
1answer
147 views

What are possible causes for consistently volatile INSERT performance in MySQL tables?

I have a Java program running on a VM that is sequentially feeding a queue of single row INSERTs through a single connection to a MySQL server on the same VM. The queue execution is not artificially ...
2
votes
3answers
137 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 ...
1
vote
1answer
496 views

SQL Server performance is slow when migrated from SQL Server 2012 to SQL Server 2014

We are trying to migrate from SQL Server 2012 to SQL Server 2014 on Windows 2012 R2 OS. After the upgrade, we are doing performance testing and observed huge difference in running a simple query from ...
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), ...
0
votes
2answers
19 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 ...
2
votes
1answer
58 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
195 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 ...
0
votes
1answer
190 views

MYSQL: How to improve performance of inserting over 1M rows to a table with over 100M indexed rows

I have this mysql table: CREATE TABLE `codes` ( `code` bigint(11) unsigned NOT NULL, `allocation` int(11) NOT NULL DEFAULT '0', `used` tinyint(1) NOT NULL DEFAULT '0', PRIMARY KEY (`code`), ...
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 ...
2
votes
1answer
149 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
1answer
26 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 ...
1
vote
1answer
506 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 ...
6
votes
2answers
151 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 ...
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 ...
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 ...