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
4answers
417 views

Is there any scenario where the existence of one or more Indexes in a table can prejudice it?

The title sums it up. I've learned and always heard that indexes in tables improve CRUD operations. A developer that I met last weekend told me that he does not like Indexes because they are bad - ...
0
votes
1answer
58 views

sqlite database table with 1000's of columns

I am using sqlite3 in an application to conduct an alalysis of distances between sets of points. Distances between these points have been precomputed using dijkstra's algorithim and left me with a ...
1
vote
1answer
192 views

Vertica performance on select from view with union

We have a huge number of rows(tens of millions), and for each table we have an associated view that is a select with UNION ALL between that table and several others. Now, we are doing a select from ...
6
votes
1answer
154 views

What is more appropriate sp_updatestats or UPDATE STATISTICS?

In a system there is a nightly data load process where all the foreign keys are dropped, all tables are truncated, repopulated from an external source, and the foreign keys are put back in place. At ...
0
votes
0answers
61 views

MySQL performance issue after migration

I have a MySQL performance issue with a brand new server, and am somewhat of a beginner as a database administrator (I'm mostly a general-purpose Linux sysadmin). I'm looking for pointers where to ...
5
votes
3answers
462 views

Warning about implicit convert

I have table with 2 name columns: CREATE TABLE Test ( TestID int identity primary key clustered , Name_Eng nvarchar(50) , Name_Nat nvarchar(50) ) Now I need a query to get this Name column ...
1
vote
1answer
55 views

Best way of order processing

I would like to write a procedure for order processing Single Order can have multiple items, how can I process the order ? Consider below JSON is an example: { "Order": { "OrderId":...
1
vote
0answers
25 views

PostgreSQL: Improve system performance, KNN modification with GiST Index

In my PostgreSQL 9.5beta2, Postgis 2.2.0 compiled by Visual C++ build 1800, 64-bit I am running a Nearest-Neighbor-Query with the additional complication of unique assignment. I am running this on i5-...
1
vote
1answer
30 views

Update all rows when sort/ordering value is changed for single row?

I am in the process of creating a GIS application with multiple layers and many pieces of content shapes on each layer. Currently each layer/shape is drawn in the order that it was returned from the ...
0
votes
0answers
22 views

MySQL 5.6.18 got signal 11

My MySQL Server 5.6.18 got signal 11 today very randomly. Has not happened before. This is the stack trace : stack_bottom = 7fdb9bcb1e0f thread_stack 0x40000 /usr/sbin/mysqld(my_print_stacktrace+0x35)...
0
votes
1answer
74 views

AWS EBS I/O Bottleneck

I'm hoping someone can help me understand some EBS Bottlenecks that we are experiencing with a new Windows SQL Server instance we're configuring. We're running some tests by conducting a full backup ...
0
votes
2answers
64 views

Un-optimize a MySQL database?

I want to run ANALYZE TABLE and OPTIMIZE TABLE on a large production MySQL database (v 5.0) to increase performance. But as this would lock tables causing downtime for an unknown amount of time, I ...
21
votes
2answers
919 views

IF EXISTS taking longer than embedded select statement

When I run the following code it takes 22.5 minutes and does 106million reads. However, if I run just the inner select statement by itself it only takes 15 seconds and does 264k reads. As a side note, ...
0
votes
1answer
32 views

Perfmon Counters that relate to SQLIO

I am trying to benchmark a new virtual SQL server. this will be the first time I have virtualized a production SQL server. I don't think this is a supper busy server. 100-200 users, of varying ...
1
vote
0answers
45 views

SQL Server 2012 AG replication issues

We just went away from SQL Serer clusters in SQL Server 2008 to SQL Server 2012 with AG – have five servers with replicas in a secondary datacenter and syncing over a dedicated eline/LAN layer 2 ...
0
votes
0answers
68 views

How to optimize this query on oracle?

I have built this query in oracle to get some data i need from the two tables below. At SELECT REGEXP_REPLACE i get the IN_01 as input parameters from the user and it can be much bigger list than that(...
1
vote
1answer
130 views

Index performance for CHAR vs VARCHAR (Postgres)

In this answer (http://stackoverflow.com/questions/517579/strings-as-primary-keys-in-sql-database) a single remark caught my eye: Also keep in mind that there's often a very big difference between ...
-2
votes
1answer
24 views

Application load considerations, use what you get vs. not all at once

General question: Should I as an application use all resources I can get and thrust the OS schedeuler or should I already do some load considerations for the OS. If so, what metric should I use? ...
0
votes
0answers
79 views

Linked Server to Oracle seems to be slow

we have a linked server between a SQL Server 2008 R2 instance and an Oracle 11.1.0.7 instance using OraOLEDB.Oracle Provider. The enabled options for provider are: Dynamic parameter Nested queries ...
1
vote
1answer
64 views

Which database should I look at for analyzing ~30gb, 700M records dataset?

I'm looking at analyzing a kaggle dataset which is pretty normalized, specifically joining, grouping, slicing and dicing the 3 tables patients(2M) <-> diagnosis(700M) <-> doctors(2M). I ...
2
votes
1answer
61 views

Primary key addition for a table which contatins no data is too slow

We are using mysql. We are running 10 alter queries which contains 3 Primary key deletion and 4 column addition and 3 primary key addition. And this alter query is on three tables which don't contain ...
0
votes
0answers
38 views

Database calculations question

I am creating a MySQL database that is going to be used to store a lot of timestamps. There are currently 6 timestamp fields that data can be entered for one row. I am utilizing timestampdiff to ...
1
vote
1answer
120 views

Error in loading data using DB2 load command in DB2 10.5 [on hold]

I have a IBM DB2 database in our application. We have a monthly Java batch process which loads data in the tables using "load Replace" sql command. Around millions of record will be updated every ...
4
votes
2answers
479 views

SQLServer:Buffer Cache Hit ratio is a good indication of POSSIBLE memory bottleneck?

I am looking for an indication (if any) that would either disregard the memory bottleneck option, or accept it, or make me investigate further. for instance: page life expectancy: SELECT [...
-3
votes
0answers
39 views

Procedure taking so much time [closed]

Can anyone help me out. This is first time im working on performance tuning can anyone help me out. If want i can paste the proc also.
1
vote
3answers
69 views

Will different tables for different Users help in performence

I have this Posts table. Somehow Read/Write ratio is 50:50. And we have to write very frequently. Now suppose I am going to update 1000 post 500 users each, every minute. I think this will overcrowd ...
1
vote
0answers
35 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
252 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
votes
1answer
73 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
68 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
68 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
vote
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
224 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
87 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
vote
0answers
51 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
214 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
27 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
27 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
222 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
413 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
227 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
80 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
65 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
42 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
49 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
131 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. ...