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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High disk IO from MySQL database on Ubuntu

We have a MySQL database (the master in a master-slave setup) running on Ubuntu that is experiencing high disk IO as reported in newrelic and by iostat. Now, the server normally has ~150 connections ...
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17 views

Seconds behind the master is getting increased how to reduced that. since i haveupdated my salve and started back the replication [on hold]

MariaDB [(none)]> show slave status \G; *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: ...
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25 views

Identifying high load sql

We had an oracle outage some days ago. We have inbetween awr tools. I genarated awrrpt report but dont see anything suspicious. Which report should I generate to see sql, which caused very high cpu ...
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1answer
23 views

Is it good to save Keywords stored by users in a new DB schema?

My question is more from the schema design and of further performance of the DB. I'm designing a DB schema which will store primarily strings. Actually, users work on these string, as normal mortals, ...
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1answer
72 views

Is adding the join columns to a table a good practice to improve performance?

Say we have 3 tables, A, B and C. Assume all table relationships I refer to below are 1 to many. Suppose A joins B in a1 = b1 and B joins C in b2 = c1. Is it a good practice to add b2 and a1 to ...
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1answer
31 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 ...
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1answer
54 views

Deleting large amounts of cascading records with minimal locking

I'm looking for a strategy to purge large amounts of logically deleted data from a MySQL database. The deleted records are in a relatively small table, but are referred to with many ON DELETE CASACDE ...
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26 views

Slow inserts in oracle 12c inmemory table

We are running some tests to check the in-memory performance on a 12c (12.1.0.2.4 EE) RAC. Servers have 56GB memory and 20core CPUs. Our plan is to have a few read-performance critical tables in ...
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3answers
144 views

Setting maxdop 1 vs setting the threshold for parallelism high

I am looking at a possible fringe case for parallelism settings. I've long since followed the credence that maxdop 1 is a viable option for Microsoft Dynamics CRM databases. As the nature of the ...
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1answer
52 views

How can I minimize impact of expensive queries in Database A on Databases B, C, D

How can I configure SQL Server so that activity in 'Database A" has minimal impact on users in 'Database B' The Context Our (very large) production SQL Servers have a lot of databases on them ...
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1answer
20 views

MongoDB 3.0 Indexes maximum limitation

I have a mongo DB that store user's public messages. Each message should be categorized by at least one TAG (3 max in an array) The TAG can be anything up to 32 characters. ([0..9a..z]) the Tag ...
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1answer
50 views

Mysql Slow when join query running increaed

Our Mysql dedicated server box always have around 40 - 80 active user connection , so the query speed very good and Cpu usage low . (around 4 - 8 core from 24 core) but sometimes when some wordpress ...
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1answer
65 views

4m Rows in MySQL, ~5 Minutes to Run Query

I have 2 tables, a users table and a log table which literally logs each time a user signs in. What I'm trying to do is grab a list of all users with a certain rank who have not logged in for over a ...
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1answer
32 views

Why is my Target Server Memory slightly higher than my Total Server Memory?

I'm doing a performance test on a high traffic (16000+ users, estimated 1000+ concurrent at peak) Microsoft Dynamics database. The server has gone on line a few months ago, and I'm doing some tests to ...
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0answers
27 views

Speed of Split Database vs ODBC with SQL Server vs ODBC with Azure Cloud

I would like to be able to host my data either in the cloud or in SQL Server, as having all my data in one Access file just doesn't seem the most secure to me (or am I wrong?). My forms contain many ...
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1answer
36 views

Creating index for large table is taking forever

I am trying to create Index for a large table with row count of 496,000,000 and the database is on SQL Server 2012 Enterprise edition. I know how to create index but its taking forever and would like ...
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1answer
85 views

ASP.NET & SQL Server 2012 timeouts once a month

We have an intranet site which works fine, except one day a month. There are slow queries, unoptimized tables, tables with ~8 million records, etc. but daily usage is fine, although some ...
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41 views

Upsert - Should I verify the row exists first, attempt an update, or try to insert first?

In a software that I'm working, I have a table with a few columns and a id. In some events in my software, I need to update some column of a record with a certain unique field (other column), but ...
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64 views

Creating MSSQL Performance Baseline Monitoring

In order to get an overview and compareable data my current task is to create a performance baseline to get some figures about the different productive sql instances. My thoughts are: I want to ...
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1answer
29 views

Things to keep in mind while editing Mysql “my.cnf” file

Today I tried to boost mysql's(installed in my system Ubuntu 14.04) performance as I have many sites(PHP/Magento) installed in my system which relies on mysql as database server, but when I edited the ...
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2answers
46 views

Identical SQL Server databases hosted in the same physical DB server

We have hosted similar SQL Server 2014 databases TestDB and TESTDB_Copy on the same physical server. The two databases are almost the same and there may be minor differences in the number of records ...
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1answer
90 views

Increase SQL Server Performance

I have a fairly simple SQL Server 2014 Standard database with one main table. Here's the workload: I insert a row, do a few updates to it (up to 5 updates), and move on. I always update recent rows. ...
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1answer
90 views

Low CPU Utilization but High Signal Waits

I have a server with 16 CPUs that is configured with a max degree of parallelism of 8 and a max worker threads setting of zero. For a given hour, my signal waits were 20% yet my OS CPU utilization ...
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1answer
41 views

Is it worth time converting Access query to T-SQL query

Let me just say, before anything else, that I am a enormous noob when it comes to databases in general, so please forgive me for my rather stupid thoughts and actions. I had a database built in ...
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43 views

Metrics for performance of Oracle

I am trying to measure various metrics for a stored procedure - that we are tinkering with and using under different loading (i.e. size of tables). So I have drawn up this list of metrics to plot ...
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2answers
439 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 ...
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1answer
50 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 ...
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1answer
16 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 ...
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2answers
115 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 ...
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0answers
31 views

SQL Server 2014 vs Amazon Redshift performance [closed]

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 ...
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38 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 ...
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0answers
44 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 ...
4
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1answer
49 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 ...
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28 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 ...
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1answer
72 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 ...
13
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1answer
1k 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 ...
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37 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 ...
3
votes
1answer
62 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
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1answer
39 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 ...
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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 ...
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2answers
202 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
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2answers
21 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 ...
0
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1answer
21 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), ...
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2answers
111 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
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1answer
95 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
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1answer
83 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 ...
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3answers
205 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 ...
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3answers
149 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 ...
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2answers
59 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 ...
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1answer
41 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 ...