Improving the performance characteristics of a database application or system.

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4
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1answer
46 views

Is it possible to connect MS SQL Server Express 2012 through DAC Connection?

Is it possible to Connect MS SQL Server 2012 Express Through DAC. After moving from SQL Server 2012 Enterprise to MS SQL Server 2012 Express, some performance problem were there. When i have checked ...
2
votes
1answer
279 views

Stack Dumping and performance degradation of sql server process [closed]

I would like to say that today i got first time SQL Server log message in My SQL Server 2012 Database. ***Stack Dump being sent to D:\MSSQL11.MSSQLSERVER\MSSQL\LOG\SQLDump0012.txt * *****************...
0
votes
2answers
62 views

MySQL Change in execution plan after upgrade

We upgraded the MySQL 5.0 to MySQL 5.6 last week. After the upgrade most of the DMLs are very slow. Especially the inserts and updates using JOINs. There is a difference in execution plan of these ...
3
votes
2answers
196 views

Release MySQL Memory and Performance Tunning

I am new to the MySQL database. I have recently installed MySQL 5.7 and configured the my.ini file. Please find the below copy of the file. The server is a dedicated server for MySQL database and the ...
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 ...
0
votes
2answers
48 views

More Efficient Use of Union

Looking for a more efficient way to achieve what my view is doing. This view joins tables to themselves to show where each part in the database is used. In other words if I am a part of a part list ...
1
vote
0answers
99 views

How Can I Increase Performance of This MERGE Statement?

I have a INSERT INTO/MERGE statement that is part of a stored procedure that needs to be really efficient. The execution plan shows that 90% of the procedure is due to the following statement shown ...
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) ...
0
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0answers
20 views

server response is getting slow day by day

MySQL server 5.5 > running in Linux Box is getting slow. MySQL server is being used by Java Web application, please help me to figure out the problem.
0
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1answer
45 views

Tuning read-intensive queries - Oracle

Now this might be very vague but Im sure I can provide more info on them.. my query is that is it recommended to use tablespaces if different block size because I have a table in which number of reads ...
3
votes
3answers
257 views

Can I find out which database is queried on the most?

We have a number of database which all have the same schema for each customer. I was wondering if there was a query which could select count(*),db_name from somesysview group by db_name; From a ...
3
votes
1answer
863 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
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0answers
51 views

Optimizing DB for performance by archiving/partitioning

I have a table in my Database which would be loaded with huge amounts of data each day. These are basically status of the orders customers has placed. The UI in my application which calls the DB for ...
1
vote
0answers
227 views

Mongodb Huge Number of Open Connections and Write Locks

We are seeing around 800 open connections to our Mongodb. To clarify our issue: We have 5 different clients who write the data into Mongodb. Each of these clients - write four different type of ...
3
votes
3answers
194 views

Simple yet problematic update query

I have a rather simple update/query, that has been causing me a lot of grief over the years. in simplest form it is : update VillageSemaphore set TimeStamp = getdate() where VillageID in (...
0
votes
0answers
32 views

Minimum Oracle table size making IOT advisable?

I have inherited an IOT that doesn't seem to merit it because: only 25k rows fairly pure join table, non-index fields rarely queried total index width only ~125 bytes total row width only ~160 bytes ...
0
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0answers
146 views

Why my mariadb slow when I select all from empty table?

I try to find why my database slow when I select all table . That's empty table... MariaDB [kohadata]> select count(*) from biblio; +----------+ | count(*) | +----------+ | 0 | +----------+ ...
2
votes
2answers
63 views

Can moving tables to another MySQL database help performance?

I want to know if I using different databases can help performance. I have one big table support_chat with more than 5 million rows. I need to scan this all the time (3s with ajax) to check new ...
1
vote
0answers
55 views

Mariadb improve performance while import dumpfile

I have a dumpfile with millions data inside. I want to decrease time because I waited too long. I imported 10 million data (3 GB) and I waited 1:30 hours. I will import nearly 100 million data (30 GB) ...
4
votes
1answer
608 views

Do I have a memory issue?

I ran sp_Blitz that pointed me to a memory issue saying: Memory Dangerously Low The server has 32755 megabytes of physical memory, but only 235 megabytes are available. As the server runs ...
0
votes
1answer
61 views

Sql Server 2012 Failover Replica in Synchronous Mode between Primary-Secondary on VPN is very slow

I have installed SQL Server 2012 Clustered HA with Replica in Sync mode between two nodes connected by an high-speed VPN. The DB is encrypted. Everything works fine, but to do the replication, the HA ...
13
votes
2answers
317 views

Why do SQL Server row estimates change when I add a join hint?

I have a query that joins a few tables and performs pretty badly - row estimates are way (a 1000 times) off and Nested Loops join is chosen, resulting in multiple table scans. The shape of the query ...
0
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0answers
61 views

SQL Server File Latency

I've a Database which is in SQL Server 2012. For the last couple of weeks it's very slow and some times not responding to the queries. So I checked the read/write latency and the result is - Read ...
3
votes
1answer
134 views

How to tune the query on all_constraints in Oracle 12c?

How to tune the following query, as it's taking around 8 seconds: select constraint_name,table_name from all_constraints where r_constraint_name in ...
2
votes
0answers
83 views

PAGEIOLATCH_SH and WRITELOG waits

We have a slow overnight process which I was asked to look at with the top waits being PAGEIOLATCH_SH and WRITELOG I have been collecting information from sys.dm_io_virtual_file_stats and can see ...
8
votes
1answer
260 views

Does RSS Profile have an effect on SQL Server with NUMA setup?

I'm curious whether the RSS Profile which is default NUMAStatic on Windows 2012 R2 could/should be changed for SQL Server with a NUMA setup. Has anyone done performance benchmarks on high load SQL ...
0
votes
1answer
144 views

Identifying root cause of high cpu load

I need to research what caused a high load in our Oracle database some days ago. I wish to see a list of of high-load SQL statements. We don't use any Oracle tools like ADDM or AWR. I tried to ...
2
votes
1answer
59 views

Associate SQL Server Queries with Databases

Is there a way via T-SQL and DMVs to show which database a query was run against? The goal is to look at CPU and I/O by query by database so I can redistribute the databases as I reconfigure the ...
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0answers
93 views

Update queries randomly slow on INNODB Mysql

I have been struggling with a slow update query. Have already tried using indexes and other query optimization techniques. I have been using MYSQL database with INNODB engine. The issue is that, ...
1
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0answers
23 views

Several Data Importation Illogical Latency in MySQL [closed]

I am used to importing a 4GB of data from an .sql file towards a testing server (hardware). I tweaked the database to speed up inserts, and, so far, the script takes 6 hours, more or less. We were ...
1
vote
3answers
54 views

Speeding Up MySQL Full Text Search

I am doing a complex full text search on a table with 130k+ records. It takes .5 seconds to complete. I was hoping it would be a bit faster. Is there anything I can do to make it faster? Below is ...
3
votes
1answer
217 views

PostgreSQL doesn't use all the RAM it could

I'm having performance issues with my PostgreSQL 9.4.1 server. I have tuned the server using the usual best practices (pgtune + google). Here's the relevant config: # <snip> the default config ...
0
votes
1answer
147 views

Oracle 11g PGA advice view is empty when it shouldn't

I have the following situation in an Oracle 11g server (it's part of a RAC). PGA_AGGREGATE_TARGET is set, STATISTICS_LEVEL is TYPICAL, and yet V$PGA_TARGET_ADVICE shows up empty. Why does this happen? ...
7
votes
2answers
4k views

Latin1_General_BIN performance impact when changing the database default collation

I have set the database collation to Latin1_General_BIN, to make string comparisons case-sensitive. Will this have an impact on performance? Will it have any impact on DML or DDL operations in the ...
1
vote
0answers
264 views

DB CPU parameter in AWR - Oracle

What is the significance of DB CPU paramater in Automatic Workload Repository? Say in my case it's always above 100. Does it have benchmark metric as such to say that so and so number is the right ...
1
vote
0answers
34 views

Why do Statistic recommendations disappear from DB Tuning Advisor after implementing recommended indexes?

Why is it, when analyzing a query through Database Engine Tuning Advisor, statistic recommendations disappear after some or all of the suggested indexes are implemented? For example, Query X suggests ...
2
votes
1answer
967 views

Can I exchange partition between two table with partition with same name?

I am trying to restore one partition from a backup table. Both tables have partitions with the same name. My goal is to grab the data from the backup table partition x and put it in original table ...
1
vote
1answer
24 views

Access to Server and Real Data for Performance Tuning [closed]

I'm newbie in performance tuning (PT) in SQL server and I have read some documents about how to do it. It is based on theory from the articles or books. The next step to is to learn about it by ...
15
votes
4answers
1k views

Should the index on an identity column be nonclustered?

For a table with identity column, should a clustered or non-clustered PK/unique index be created for the identity column? The reason is other indexes will be created for queries. A query which uses a ...
1
vote
2answers
650 views

How to tune a stored procedure that is fast on test data but slow in production

If you have a SQL Server 2012 database with test data in development and preproduction phase and the real from the company's server take place only in the production phase. In other words, the real ...
1
vote
1answer
58 views

Tuning MySQL query from explain

I am working on a search query in MySQL. I am getting this from explain: Original screenshot These are my indexes: Table definition: Original screenshot Query: SELECT `t`.`id` AS `...
3
votes
1answer
406 views

Postgres 4x Slower Than It Was

Our Postgres performance has gone down to 1/4 of what it was, and we can't figure out why. We have two machines with identical hardware (let's call them A and B): Intel(R) Xeon(R) CPU E5-4640 0 @ 2....
2
votes
1answer
202 views

Dropped Index during Database Engine Tuning Advisor

I was analyzing a query using "Database Engine Tuning Advisor". During this time the database started to get blocking, long running queries and ended by restarted the instance. When I checked after ...
0
votes
2answers
59 views

Finding the longest entries for a given column (nvarchar(100))

I am trying to find the biggest / longest entries of a column which is of type nvarchar(100). I need to understand if I can maybe restrict that column to be only nvarchar(20) or something. Is there a ...
3
votes
1answer
177 views

MySQL (MariaDB - 10.0.16-MariaDB-1 (Debian) strange performance issues

I am running version 10.0.16-MariaDB-1 (Debian GNU/Linux 8.1 (jessie)) on Dual Xeon CPU, total 32 cores with 128 GB of RAM. This is a dedicated DB server and has been recently migrated over from ...
2
votes
1answer
20 views

Is Oracle 10g smart enough to work on a WHERE clause identically as the equivalent INNER JOIN?

Way back when Michael Jackson was still alive, I made this question: http://stackoverflow.com/questions/1018822/inner-join-on-vs-where-clause And now I'm performance-auditing a system in which the ...
2
votes
0answers
81 views

MySQL memory is keep on increasing , any reason?

On one of our production host MySQL memory is keep on increasing day-by-day. I tried reboot of MySQL instance but still no avail. System has 16Gb of RAM. TOP output top - 13:05:13 up 35 days, 1:...
0
votes
1answer
67 views

NC Index not being used [closed]

I have a table (9mm records) with a field called filename nvarchar(max)(I didn't decide on this datatype and can't change it). I'm wanting to count how many records meet the following criteria: ...
4
votes
1answer
52 views

How to increase performance in Cross Database operations?

We currently have a SQL Server 2008R2 being accessed by a legacy ASP application. Among different processes, one of them essentially SELECTs data from one database and INSERTs (or UPDATEs) them into ...
2
votes
1answer
58 views

Accurate PG database size for comparing representations

I have a Java/JDBC program that takes a sample file and imports the data into the database, shredding it across multiple relations. The program does this multiple times for several different ...