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

1
vote
1answer
39 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
147 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
727 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
197 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 ...
4
votes
3answers
232 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
238 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
92 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
108 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
512 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
25 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
85 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
64 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 ...
4
votes
1answer
82 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
78 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 ...
7
votes
1answer
98 views

Two servers, different execution plans. Several orders of magnitude difference in run time

Two servers, Development and Live. Live server is an Amazon RDS SQL Server Web instance. Both servers have identical schema and data. There is a good spatial index on the geometry column. On my ...
3
votes
2answers
214 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 ...
3
votes
1answer
185 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
82 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 ...
6
votes
0answers
125 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 variables/results from data analysis for quick selection in post-processing. If stored, I think it is well ...
1
vote
1answer
58 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
91 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 ...
5
votes
0answers
134 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
58 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
93 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
394 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
77 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 ...
8
votes
2answers
155 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
191 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
288 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
125 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 ...
6
votes
1answer
2k 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 ...
3
votes
0answers
94 views

Why the stored procedure is much slower than a temporary table? [closed]

I want to do the updating of my database every day and I will like to use stored procedures but the time of execution of the temporary table is faster than the stored procedure. How can I optimize my ...
10
votes
1answer
183 views

Why is query thousands of times slower with DESC?

I have a PostgreSQL database (AWS RDS) and ran the following queries in psql: livenet=> EXPLAIN ANALYZE SELECT * FROM outputs ORDER BY height LIMIT 10; Limit (cost=0.57..36.82 rows=10 ...
1
vote
1answer
250 views

Why is my stored procedure very much slower than the same MYSQL query? [duplicate]

My stored procedure is very slow compared to a normal query or a temporary table. How can I optimize my stored procedure? CREATE DEFINER=`datasll`@`...` PROCEDURE `product`() BEGIN EXPLAIN ...
12
votes
1answer
340 views

Why does referencing a variable in a join predicate force nested loops?

I came across this issue recently and couldn't find any discussion of it online. The query below DECLARE @S VARCHAR(1) = ''; WITH T AS (SELECT name + @S AS name2, * ...
1
vote
1answer
71 views

Intervals query of huge data

My question is more or less theoretical - what is the best approch to get query data by intervals. The situation I have a system that manage counters (thousands of counters - counts consumption of ...
1
vote
5answers
130 views

TSQL insert table using view — performance issue

I have a big view joining multiple tables that in a regular basis materialists itself into a table (this step occurs for viz's tool read a table instead of a view during data source refresh): select ...
1
vote
1answer
118 views

Automatic migration failed on Azure Database

I am using Entity Framework 6.1.1. The database has three million records; migration has to change the precision of a column of type decimal. The migration timeout window is set to the maximum value, ...
0
votes
1answer
45 views

Get all possible parent ids only if has parent bigger than 0

Right now If I call get_parent_id(4) I will get all id parents. This means 3,2,1. Is not hard to guess that 1 has parent 0. This is my problem. I want to output all ids unless the parent is 0. To do ...
1
vote
1answer
69 views

RDS Postgres Peformance

I have recently set up a new RDS instance to test out working with a AWS postgres instance vs a heroku postgres instance. What I've found is that when I load an instance of 1000 entries in RDS its ...
0
votes
1answer
279 views

Using TEXT or even MEDIUMTEXT for all text columns in a MySQL table?

I'm using a PHP script to insert millions of rows into a MySQL. Each of the rows contain a diversity of columns that are very different across the rows. Basically I'm using MySQL as a key-value pair ...
1
vote
1answer
120 views

Disk Read IO Throttle not showing in perfmon Windows Server 2012 r2

I am working on Windows Server 2012r2,SQL Server 2014. I am trying to create a new data collector to review Disk IO in perfmon. When I get to the step to add the available counters there is no Disk ...
0
votes
1answer
238 views

SQL Server Data File/Log File poor performance

I've been asked to look at a database/application server that's "performing slow". No one could really tell me what was performing slow (except for the database backups) so this has been a discovery ...
1
vote
3answers
390 views

Are TEXT fields stored separately from the row in MySQL-ISAM?

We have a "notes" table and some of the queries are getting very slow even though we're not searching on the note contents. We're wondering if moving the note content into a separate table would speed ...
1
vote
2answers
184 views

High SOS_SCHEDULER_YIELD and Signal Waits

I have run Paul Randals wait script and can see SOS_SCHEDULER_YIELD is at 60% with an average signal wait of 10ms. I have also run a script to find out the what percentage of my waits are signal ...
2
votes
1answer
747 views

Indexed VIEW in SQL Server with PIVOT

A simplified version of my problem is as follows: I have three tables Records, Inputs, and Outputs. Records Id DTS   1  2015-01-01 00:00 ... Inputs Id RecordId ...
1
vote
1answer
154 views

Divide a PostgreSQL database into schemas

My Postgres database will be focused on multidisciplinary organizations. The project axis is: a person could belongs to diverses disciplines (ex: arts, sports) for the same organization, and this ...
1
vote
2answers
103 views

Will frequent small select queries slow down frequent write queries in InnoDB table in MySQL?

I'm running a MySQL database with tens of tables in remote server. To monitor the data, I write a small program to query to database via VPN connection every 10 seconds. Each query is a union of 20+ ...
0
votes
1answer
46 views

mysql Quiz leaderboard filter by points, time taken

I have a quiz report table which shows a report for every quiz a user takes. I need to create a leaderboard from this, which shows the top users best score, filtering by points and then time taken. ...
1
vote
2answers
272 views

Slow “CREATE TABLE” and “TRUNCATE” on MySQL / MariaDB

I am fighting with performance issues on a local MariaDB instance. Fun thing: I previously had problems with all my INSERT and UPDATE and DELETE queries. This got signigicantly faster (~40ms -> less ...