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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36 views

Multiple columns VS one big-capacity-column?

I have a table like this: // table_A +--------+---------------+------------+ | id | short-text | long-text | +--------+---------------+------------+ int(11) varchar(200) text ...
9
votes
2answers
255 views

To partition or not to partition?

Having already read several questions on SO, external blog posts and manual SO: Foreign Key constraint to partitioned table in Pg dba.SE: Different ways of handling FK to partitioned table in Pg ...
0
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1answer
74 views

mysql: expected time for a simple group by on a single table, 2M records, single user?

related to MySQL tuning (my.cnf) for very large tables and ad hoc queries I have a really small table with 2M records, on a 32GB machine, running Windows 10 Pro with nothing serious running except ...
5
votes
1answer
69 views

Are there practical scenarios where inserts + deletes are faster than updates? (SQL Server)

I'm just wondering if there are common scenarios where an insert/ delete combination is faster than an update else insert function. Here is my specific example. I have to update a database with ...
6
votes
1answer
69 views

SELECT xyz INTO #Temp from SSMS is 5x longer in one environment than another [closed]

First time posting, I hope I'm doing it right. I'm a "dba by accident" who is learning a lot but admittedly still has a lot more to learn. Here is my brain dump: Prod server has 5 million rows. I ...
1
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0answers
43 views

PostgreSQL long transaction on a table performance

We have a long processing pipeline running on PostgreSQL 9.0. Is it faster or slower to perform many operations on a single table within one transaction, versus doing auto-commit for each operation? ...
4
votes
3answers
263 views

Does an order by clause have a negative effect on performance?

I couldn't find the answer by googling. I only over heard a senior dev telling a junior dev that using an order by clause has a negative effect on performance and he shouldn't use it(Oracle). In ...
5
votes
1answer
97 views

Measure Performance for INSERT, UPDATE and DELETE commands on DB2

I have a DB2 database with a table for daily transactions, which is cleared to a history table at the end of the day, every day. I insert rows to this table via java-JDBC INSERT commands and they ...
3
votes
0answers
51 views

Proc Cache Drop Assistance [duplicate]

We are noticing performance issues with one of our applications. When the application issues begin the procedure cache size goes from 4.5GB to 0. The plans are then rebuilt and still the application ...
1
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0answers
54 views

Is PostgreSQL text really that much faster than Oracle CLOB? [closed]

I have an oracle 10g table with 1 clob column. The clobs aren't very large mostly around 2-8 kb. However reading many rows takes an excruciating amount of time. Even with storage in row enabled. I ...
11
votes
2answers
58 views

Why do my Batch Requests increase when doing a Differential Backup

I have started doing some long-term tracking of various activities on our 2012 SQL Server and I have noticed an increase in Batch Requests during our incremental backups. To give an idea, normal day-...
3
votes
2answers
260 views

Deciding EC2 Instance type & Volume IOPS for Mongo DB

We have 500GB data in our Mongo(v2.6.3) including the indexes. We currently run this on AWS m3.large(8GB RAM) instance. Yes, Single machine. Our MongoDB Cloud Manager shows these stats: ...
0
votes
0answers
28 views

calling multiple procedures from my application Vs calling procedures inside another procedure

I have a scenario of saving user details into my database(MySQL 5.1); i have three tables for saving user details; user_data,user_contact,user_address, so if i insert one user data i have to check for ...
0
votes
1answer
74 views

How to optimise multiple joins with OR?

I need to extract some statistical information form drupal database tables. The problem with drupal is that it splits it's data for entities across multiple tables and getting simple information from ...
0
votes
0answers
31 views

T-SQL script to analyse recent changes in SQL Server configuration?

Last week suddenly one of our VMs running SQL Server slowed down considerably and its performance dropped to the level where some of us cannot work on it any more. Just to give you an idea about the ...
1
vote
1answer
285 views

Postgres 'could not write to hash-join temporary file: No space left on device'

I was getting this error a while ago and I was curious about two things - 1- How do the internals of postgres work that cause this message to occur in the first place? What is the hash-join in ...
1
vote
1answer
488 views

memory usage oracle query

We see Direct path read temp frequently in the database. It started with one query and later followed up to all the queries running in database at that moment. I understand that data is read from ...
8
votes
3answers
228 views

Application querying empty tables

My company uses an application which has pretty major performance issues. There are a number of problems with the database itself which I am in the process of working through, but many of the problems ...
2
votes
1answer
83 views

SQL Server is running slow after a certain amount of time [closed]

We've been experiencing some issues with our SQL server recently. I have noticed that some of our SQL jobs are running longer than normal. One job normally runs in under 3 minutes will take over a ...
0
votes
2answers
69 views

Optimal database structure for fast inserts

I am using MySQL Percona server. This table needs to do fast bulk inserts using 'INSERT INTO ... VALUES' for smaller requests (about 100k records) and using 'LOAD DATA INFILE' for larger (up to 10kk ...
1
vote
1answer
45 views

Update by iterating table in batches faster than whole table in PostgreSQL

I have a table with approximately one million rows. It is being used in production and I ran an UPDATE which covers ~95% of those rows. After five hours I cancelled the request because it was taking ...
0
votes
0answers
56 views

MySQL performance affected by calling functions from inside procedures?

this is the very first question I post, so please bear with me ... When working on a project, I tried to get the LAST_INSERT_ID for a table, by invoking it from inside a procedure right after an ...
-2
votes
2answers
142 views

Random numeric string as a primary key - security, performance, efficiency?

I'm building an app aimed to store lots of records (millions) and trying to find a best way to store records identifiers that is publicly accessible from the web (record URL). I'd like to get: ...
0
votes
0answers
18 views

Sudden performance gain when performing mysql queries twice, lacking on live host

I was having performance problems and could improve it down to 14 seconds roughly per execution (if you see any way to improve that further, I would be really thankful). Which, is still very slow. ...
6
votes
1answer
246 views

How does SQL Server calculate the initial size of a (compressed) backup?

When a backup is created, SQL Server guesses(?) the a size of the intial backup file. Later on, maybe when it appends the log the size will be re-adjusted, sometimes multiple times until the final ...
1
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0answers
48 views

Improving PostgreSQL cluster performance

I am trying to cluster my table faster. The table is 27 GB worth of data, and has one index using a point geometry which is 19 GB in size. I am seeing about 5.5 hours to cluster the table. I am ...
3
votes
1answer
56 views

Are database connections from an application expensive from a performance point of view?

A colleague tells me that connections to a database are expensive and could harm performance of the application. They ask me to create a procedure that calls say another 8 procedures, that way they ...
2
votes
2answers
69 views

Performance issue during count Postresql 9.4 - Creating index on pivot table key…?

Disclaimer: I am new to Postgres, I need some advice... I have a huge table, with full of poker hands.(will contain 20M records, right now 2M records in it) aggregated_hands I have a pivot table, ...
3
votes
2answers
186 views

SQL Server transferring results slowly in table result set, but instantly with XML

I have a query that left joins 100+ tables and returns 2,000+ columns, but only a few rows (10-20). This part is out of my control at the moment and it used to run ok with a bit fewer columns (maybe ...
1
vote
2answers
65 views

How to improve performance of frequently updated table in mysql?

my table structure:: CREATE TABLE `gps_device_data`( `imei_no` bigint(15) NOT NULL DEFAULT '0', `ioelementpriority` int(1) DEFAULT NULL, `longitude` int(15) DEFAULT NULL, `latitude` int(15) ...
0
votes
2answers
76 views

Best way to update list of rows in oracle database

I need to update a variable list of database rows. The list of the affected ids will be generated by an application, the statement will be executed about 100 times a day (with an always different ...
0
votes
0answers
32 views

Correlating Disk Latency on Application side Vs. EMC SAN

Our OLTP databases have encountered several I/O issues. During those events: Avg disk sec read on the data file was 0.2 second or higher We found windows eventlog entries stating: "SQL Server has ...
6
votes
2answers
306 views

Doubts in a Glenn Berry Query ( CPU per Database )

Please, if this is not place to post questions like these, let me know and I will delete it. Inside the Glenn berry's Diagnostic queries, there is a query to show how much CPU a database is using. ...
0
votes
0answers
1k views

MySQL 5.7 InnoDB is extremely slow on spatial data compared to MySQL 5.6

I have a table area which contains ~300,000 rows. It is defined as follows: CREATE TABLE `area` ( `area_id` bigint(20) NOT NULL AUTO_INCREMENT, `boundary` geometry NOT NULL, `name` varchar(255) ...
1
vote
0answers
27 views

PostgreSQL: labels vs columns

I have a data structure similar to this: date foo bar baz boo ---------------------------------------- 2015-11-18 1 null 2.5 81.0 2015-11-19 1 78.4 12.8 ...
4
votes
1answer
81 views

SQL Server Memory Shrinking

I had a strange issue today on a 3rd party vendor's SQL Server. This is a VM running SQL Server 2012 SP1. The min and max memory settings are set to 9GB. Task manager showed SQL Server was getting the ...
0
votes
1answer
418 views

MySQL Config for server with 8gb RAM and 4 cpus

I have a server with 8gb ram and 4 cpus. I don't have enough time for testing and bench marking so I would like to get the advise of experts like you guys, let me know if something is wrong with my ...
0
votes
0answers
19 views

Need some advice on db layout

I have some data that gets exported from a different system that I want to suck into mysql for some analysis. Currently, the export consists of 2 files, essentially file1 is the list of transactions (...
2
votes
1answer
100 views

Disk I/O Utilization at 95%

My disk I/O utilization is at 95% at my MySQL server. What are steps I could take to fix this? It is a Ubuntu VP with 16 GB Memory and 8 cores. Here is a screen-shot of the load:
0
votes
1answer
57 views

Does LIMIT 1 still have effect on a unique column

I know that adding LIMIT 1 when searching for only one record makes a lot of difference when it comes to performance. But does it still have any effect when we search a column with a unique constraint?...
0
votes
0answers
29 views

Does extending datafiles affect performance

We have an Oracle 10.2.0.3.0 on Windows 2003 Server which is scheduled for upgrade within the next six months. One tablespace is about 2TB in size with over 250 data files. Some of these were ...
3
votes
1answer
972 views

What does “cleaning up” mean in MySQL InnoDB transaction status and how to prevent it?

In our database (MySQL 5.6.22 on RDS) we have a lot of transactions (~500) in a state "cleaning up" under the load: > SHOW ENGINE innodb STATUS; ... ------------ TRANSACTIONS ------------ ... ---...
0
votes
0answers
28 views

Performance issue for daily calculations - Sybase Adaptive Server

I need an advice from the community, there is no wrong answer I'd like to have as many advice that I can ! I manage a process that does every day a lot of financial calculations and they are ...
0
votes
1answer
38 views

Consultants using old version of Hibernate ORM for new application - should I be concerned?

My company currently has consultants developing a Java-based application. They are using Hibernate ORM 3.5 (released 5 1/2 years ago in 2010) in this application. The back-end is SQL Server 2012. ...
0
votes
1answer
34 views

Large Sleep counts causing THREADPOOL wait?

When I run sp_whoisactive throughout the day, I usually see we have around 500-700 connections on our server. We are occasionally getting threadpool waits and high signal wait ratios (so we are thread ...
2
votes
3answers
211 views

Why do large images stored in database hurt performance [closed]

I have read on the internet that it is better to keep large images on file systems since storing them in the database hurts performance. My question is why do large images hurt db performance?
2
votes
2answers
99 views

Merge two huge tables keeping only the unique rows

I have two tables: table1 with 61 million rows and table2 with 59 millions rows. The columns in both are the same (name and type). Both are imported from backup files. I want to merge these two ...
10
votes
1answer
1k views

Why are multiple COUNT faster than one SUM with CASE?

I wanted to know which of the following two approaches is faster: 1) Three COUNT: SELECT Approved = (SELECT COUNT(*) FROM dbo.Claims d WHERE d.Status = 'Approved'), Valid ...
2
votes
1answer
150 views

Is it ok to have 'view count' column in the same table?

Let's say I have a website similar to YouTube where I'm storing and displaying the 'view counts' for each video. It is ok if I'm storing the view count column in the same table as the actual view ...
8
votes
2answers
157 views

Why is TOP operation in SQL execution plan

After searching for a while, I decided to post this question for lack of finding an answer and apologize if there is a similar question/answer out there. When running the query below on two similarly ...