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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18 views

Can This Update Query Be Made Faster?

update line_items set product_id = dups.latest_product_id from line_items as li join products p on li.product_id = p.id join vendors v on p.vendor_id = v.id join vendorgroups vg on ...
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27 views

Slow queries but CPU is not over 10-12%

I am currently stress-testing a web application and the results are pretty horrifying. The search scenario/query part on the website is the worst performing part. It takes a long time for the DB to ...
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21 views

Combine multiple query into 1 query

I have a message table that contains words field, array type, with random words of a message. Now I have an array of words [A, B, C]. I need to find the number of messages that the words contains ...
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10 views

Are there any known benchmarks/statistics on UnQLite?

I came across UnQLite the other day in Stack Overflow and it has me intrigued for some software I'm working on. However, very few tests have been published on how well it performs. There are plenty of ...
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20 views

Counting per status group makes query very slow

I have an Intranet system developed that takes in orders and every order item has their own status, i.e. "Printed", "Labelled", "Filed", etc. This query will need to count how many items there are in ...
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34 views

Oracle: How to AUTOTRACE in my program

You can display the results of EXPLAIN PLAN with explain plan for select * from foo; select * from table(dbms_xplan.display); How can I similarly display the results for an AUTOTRACE in my program? ...
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1answer
24 views

What is a scaleable database design for querying items and only returning those a particular user has not already seen?

I'm looking at database architectures that will allow the storage of a list of items a user has already seen so that I could subsequently query the items table and only show the user items they had ...
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1answer
24 views

Storing multiple IDs in column or in new table

I'm fairly new to the databases and I'm now creating little project where I have a database and I want to store deck of cards into the table where each card has its own ID (for example 52 cards in a ...
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1answer
19 views

How to improve mysql replication performance reading the relay logs in slave?

I have a mysql 5.5 row-based replication being done. The slave is slowly getting delayed relative to the master. On show slave status I see the distance between Master_Log_File and ...
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1answer
23 views

Converting a GraphDB schema to a relational database schema

I currently am using a graph database and am considering moving off of it to a relational database like Postgresql. My concern is that I have lots of relationships between entities (since this is ...
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2answers
31 views

Speeding Inserts of longtext or longblob columns

i'm currently migrating a DB2 database to MySQL, using SQL WORKBENCH Tool It basically does a select from DB2 and Insert to DB2. It works fine, but on the tables with longblob or longtext columns ...
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25 views

Tunning MySQL Variables

we have a dedicated mysql server with 10 CPU and 32G of memory After doing some readings came up with those configs : # This was formally known as [safe_mysqld]. Both versions are currently parsed. ...
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28 views

Query for a table with paging and filtering vs. CTE (common table expression)

Intro In PostgreSQL 9.3: I am building a query that fetches data for a table that supports sorting, filtering and paging. Think Customers for example, you want to show name, surname, some detailed ...
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21 views

big transaction slowdown row insertion rate [closed]

I have lots of rows inserted in a single transaction. Over time insertion rate slows down. How can I tune database to avoid performance degradation? I would like to have one transaction, so ...
2
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2answers
53 views

unusual relation, binary aspect

I have question very unusual for databases. I’m not a good English speaker, but good English reader :) so for explanation I’ll give you examples. Part1 In MySQL, I have two tables with relations ...
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2answers
70 views

Why is “select join insert” so much faster than “loop insert”?

MySQL docs state that the time required for inserts has these approximate proportions: Connecting: (3) Sending query to server: (2) Parsing query: (2) Inserting row: (1 × size of row) ...
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0answers
21 views

Performance Implications of Explicit Collation Conversions across Linked Servers

I locally host host databases from two vendors on two different SQL instances, but on the same network. These servers frequently communicate with each other (through joins and whatnot), so we have ...
3
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1answer
119 views

Can SQL Server 2008 R2 extended events execute stored procedure or query?

I'm trying to use extended events to track queries that never complete using Event Pairing as a target. (see this question I asked a few days ago). The event pairing target should let me find ...
2
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1answer
23 views

Is using MySQL views a good translation mechanism?

We want to use a foreign vendor MySQL database, but the whole schema is barely understandable by our development team. We could alter the schema to rename tables and columns once for all, but the ...
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1answer
46 views

Performance of MySQL BLOB fields processing

Suppose, I have large (about 1 GB) strings in ASCII encoding. I have to choose whether to store them as separate blob fields or split each one of them into smaller pieces and then store them as ...
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47 views

Is it possible to trace queries that never complete with SQL Server 2008 R2?

Running SQL Server 2008 R2. We have some queries that typically take less than one second to complete, but, occasionally, they are taking longer than 30 seconds which causes a client timeout. ...
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1answer
73 views

Improve Query Performance

I have the following sqlite3-Tables: db.execute("""CREATE TABLE IF NOT EXISTS STATIONS (StationUID INTEGER PRIMARY KEY AUTOINCREMENT, StationNumber TEXT NOT NULL, ...
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1answer
31 views

InnoDB Table has backed up INSERT and UPDATE queries, high CPU

I am running an MySQL DB with all InnoDB tables. I often have many queries backed up for the same table when I run SHOW PROCESSLIST; Basically, I keep a table of every logged in customer and update ...
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1answer
45 views

Can mutli-threading java client cause high CPU utilization of SQL Server 2008?

I am a Java Developer, not a DBA, and would like to consult about an issue encountered in high CPU utilization in the SQL Server 2008 (not in the Java app server). The Java client uses ...
3
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1answer
184 views

Can't get Dell PE T420 (Perc H710) perform better than a MacMini with PostgreSQL

It's months that I'm trying to solve a performance issue with PostgreSQL. SYSTEM CONFIGURATION Our deployment machine is a Dell PowerEdge T420 with a Perc H710 RAID controller configured in this ...
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0answers
42 views

Case Statements, subqueries, and datediff

First time posting on this website so please let me know if you require any other information. This first section of code worked perfectly and resulted in correct information. [Field 1] = (CASE ...
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0answers
54 views

How to resolve RESOURCE_SEMAPHORE and RESOURCE_SEMAPHORE_QUERY_COMPILE wait types

We are trying to figure out root cause of slow running sql server queries hitting/fetching data from one of the database , size 300 GB, hosted on server with below configuration: Windows server ...
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0answers
19 views

DB space vs query complexity tradeoff

I have a dilemma - Right now I have a query that I do constantly - joining 5 tables on different columns, calculate stuff per row, distinct on that, and do that with offset and limit (pagination). I ...
3
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2answers
270 views

RAID10 vs. RAID5 for data files

We are trying to evaluate the potential performance improvements that could be gained by switching an existing applications .mdf files to a RAID10 LUN vs. the existing RAID5 LUN they are living on ...
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3answers
37 views

MySQL Date field: filter by LIKE vs MONTH()

I have a CRON task that needs to extract customers with birthday in a given month, from a MySQL INNODB table. The birthday field is indexed and of type DATE. I can query the customers table by either ...
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1answer
95 views

SQL server not using the memory allocated

We have noticed that for one of our SQL server with below configuration ,memory is not getting availed as allocated. SQL server 2005 SP4, 32 bit Windows server 2003 R2 SP2, 32 bit with 16 GB ...
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1answer
71 views

Most efficient way to set up a database handling millions of links? [closed]

I'm looking at making a site that will potentially have up to a million users, and each user will have hundreds/thousands of links connected to a set of sites, as well as other info. I'm using mysql ...
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1answer
17 views

I have a DB that is locking up from numerous updates to a table: Should I convert it from MyISAM to InnoDB?

FYI: I don't believe this is a duplicate question, I've looked and most are general questions with vague answers. See more specifics below: Currently a database I am in charge of locks up every once ...
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2answers
184 views

Is it a good idea to include a value column (e.g. from measurements) in an index?

Is it a good idea to include a value column into an index for a table which has many million rows? For example a measurement table which looks kind of like this: CREATE TABLE measurements ( id ...
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1answer
55 views

Best way to rank all the columns in a table and store those ranks in another table

I have SQL Server 2008 and a table w/ hundreds of thousands of records and about 50 columns. I run a sql statement like: Select rank() over(order by col1 desc) as Col1Rank, rank() over(order by ...
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1answer
29 views

Can the number of tables and functions affect performance? [closed]

I have some big database with hundreds of functions and tables. They also have a lot of sequences, custom types and some views and triggers. There is a point when the quantity of objects will be a ...
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0answers
20 views

SQL - Optimize table population with dynamic queries

I need to optimize the following pl/sql procedure. So, fundamentally my question is: There is a way you can do a bulk insert in a pl/sql that could be more efficient than loop through an associative ...
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1answer
54 views

Poor query performance due to recheck condition on index scan

We are testing the performance of metadata when stored in JSONB compared to a traditional EAV catalogue (commonly used in biomedical scenarios), using a PostgreSQL 9.4 server. I get a problem when ...
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0answers
56 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 ...
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1answer
95 views

How can I improve this update?

I'm working with SQL Server 2014 Express edition and I want to upload some OpenStreetMaps data. Data is a 172 Mb XML and it loads ok. The problem is with this script: UPDATE ways SET geog4326 = ...
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14 views

PostgreSQL analyze only parent table only

I am moving data from a few billion records table to newly created partitions. I am inserting into the child table directly and deleting from the main table with filters on the appropriate columns in ...
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1answer
60 views

How to speed up mysql query against a 204 million record table

For some reason my server has been finicky lately and for the life of me I can't figure out why. I monitor the memory usage by running shell# watch -n 5 free -m without running any activities ...
1
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1answer
14 views

Requests to local CouchDB have 40ms latency

Requests to a CouchDB instance on the same machine have about 40ms latency when HTTP keepalive is used by the client, about 0-1ms latency when the client does not use keepalive. What causes this ...
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2answers
47 views

Max Degree Of Parallelism [closed]

What is the Best Practices for Enabling and Disabling the MaxDop Setting for SQL Server on regular basis. Is it ok to create a job and run the job as required or have the script stored as SP?
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2answers
57 views

Proportion of MySQL variables

I made some research on MySQL performance. After doing some tests and verifyed the improvement, (thank you guys) I end up asking myself: "Is there any formula or metric between groups of variables?" ...
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1answer
27 views

What is less time costly?

I'm migrating a database from DB2 to MySQL. There are big tables, so it takes a huge amount of time. The question here is: If there's a table with about 9 millions of records with InnoDB storage ...
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0answers
30 views

mysql eating RAM without queries?

Somehow MySQL eats up 50% of my RAM on the server being used. I checked and there are no queries, show full processlist is empty. I restarted the mysqld and within a couple of minutes the RAM usage ...
2
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1answer
35 views

How should a numeric value that is an external key be stored?

This is something I was pondering recently. trying to determine how to store certain values. The best wide spread example I can think of is Federal Employee Identification Number - more commonly knows ...
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27 views

PostgreSQL slow update -> does autovacuum have anything to do with it?

I am quite new to PostgreSQL as I only need it to create a map (using PostGIS). So I don't really know on hot how to optimise my DB... I have a table with a lot of polygons that I'd like to save in a ...
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1answer
112 views

Update taking too long

I am updating a table with 250 million rows in SQL Server, and it's been running for 4.5 days. I'd like to use the computer it's running on for other memory-intensive work, so I'm torn about whether ...