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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1answer
40 views

What MySQL activity eats CPU? [closed]

I have noticed weird CPU consumption peaks for MySQL process. When I monitor running queries, it's empty or some reasonable queries being executed. How do I better address the problem? Is there a ...
2
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1answer
149 views

MS SQL high tempdb disk I/O during merge replication of BLOBs

Having a merge publication for replicating BLOBs (sql type - image), got very high tempdb disk I/O for my size of data. Publication is download-only and has no filters. High disk I/O is caused by ...
1
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1answer
53 views

How do I optimise XPath Querying over a large dataset?

I have a table that has 220 M rows. Also the table has a xml column that has XML data. I have configured single file for data and another ndf for index. Table's primary key is guid column. When am ...
3
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0answers
54 views

MS SQL Server IO read increase appear randomly

The number of read (IOPS) in my MS SQL Server database increased randomly even during the night (low activities) from 0.3 MB/SEC (normal) to 25-30 MB/SEC. After like 30 minutes, it's capped to 6 ...
2
votes
1answer
69 views

Can this UPDATE be faster with indexes?

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 ...
4
votes
1answer
128 views

Combine multiple queries into 1 query

I have a message table in Postgres 9.4 that contains a words field of array type, with random words of a message. Currently I have millions of messages: \d messages Table ...
1
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0answers
100 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 ...
2
votes
1answer
71 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 ...
0
votes
1answer
47 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? ...
1
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1answer
32 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 ...
1
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1answer
82 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 ...
0
votes
1answer
77 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 ...
2
votes
1answer
36 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 ...
1
vote
2answers
118 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 ...
0
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0answers
55 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. ...
1
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0answers
72 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 ...
2
votes
2answers
60 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
281 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) ...
2
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0answers
44 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 ...
4
votes
1answer
220 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
votes
1answer
32 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 ...
0
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1answer
63 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 ...
2
votes
0answers
52 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. ...
0
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1answer
79 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, ...
0
votes
1answer
39 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 ...
0
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1answer
214 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
votes
1answer
280 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 ...
2
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0answers
96 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 ...
2
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0answers
320 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 ...
0
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0answers
24 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
votes
2answers
622 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 ...
0
votes
3answers
143 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 ...
1
vote
1answer
151 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 ...
0
votes
1answer
90 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 ...
0
votes
1answer
24 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 ...
1
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2answers
194 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 ...
0
votes
1answer
85 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 ...
1
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1answer
50 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 ...
1
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0answers
41 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 ...
1
vote
1answer
170 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 ...
1
vote
1answer
496 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 ...
1
vote
1answer
98 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 = ...
0
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0answers
26 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 ...
0
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1answer
90 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
32 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 ...
0
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2answers
70 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?
0
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2answers
64 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?" ...
0
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1answer
29 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 ...
0
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0answers
86 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
votes
1answer
41 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 ...