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Questions tagged [database-tuning]

deals with optimizing the performance of a database. It can be about file design, and selection of the DBMS, OS and platform.

Database tuning is about maximizing the performance of a database. It can include hardware, software, file system, OS and DBMS selection. See the wikipedia article for more.

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How to find out which columns are most accessed or frequently used in Oracle 12c

I'm dealing with a huge table that has 618 columns. The team does not want to embark on the research of what columns are not being used and modifying the code to delete them, and I understand the time constrain. One suggestion is to identify which…
jjsai
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Choice of a data type for a Paquet join columns (i.e., keys)

With RDBMS we usually use a numeric columns for keys (both foreign and primary), as it allows for a better joined query performance and smaller resource usage, in most cases, than other data types (like strings). The question is, what should be the…
Matvey Zhuravel
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Dropping Unused Indexes

I am referring the Unused Index Script blog. I got to know that if Seek = 0, Scan = 0, Lookup = 0, User Update = 0 then we should delete index as it is not needed. The unused script gives me many indexes but should I delete all those indexes? Can…
Yatin
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Cassandra - TWCS increased cpu usage and LiveSSTableCount

We have been historically using STCS as the compaction strategy for our Cassandra table, which was resulting in too many tombstones. Given data in the table is append only and uses a TTL of 30 days (No manual updates or deletes), we switched to…
Abhinav
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Mysql memory usage growing until OOM and system kills / restarts

I have MySQL 5.7.27 under Ubuntu 16.04.4, 64 bit, 4GB RAM and SSDs (it's a virtual machine). I am observing resident memory growth in mysqld until no more resources are available and the OS kills / restarts mysqld. Some background - The system is…
Mark Bradley
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Query Tuning and rewrite - SQL Server

Could you help to optimize the below query to perform better? Can I reduce the cost? SELECT this_.id AS id1_20_0_, this_.version AS version2_20_0_, this_.domain AS domain4_20_0_, …
Dothertechie
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Why there are current block reads in my TKPROF output on a simple select statement? Why there are two parses in one query?

In the query below, I used the sample SH schema in my query in Oracle. When I get the TKPROF output for that query, I see that, there are some current block reads. But as far as I know, current block reads happen when that block has a change on it.…
oramas
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SQL Server : How to detect appropriate timing to update table/index statistics

May I ask is there any way to get to know appropriate timing to update table/index statistics? Recently performance is getting worse with one of major data mart table in our BI-DWH, SQL Server 2012. All indexes are cared every weekend to…
Sachiko
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Mysql 5.7 performance tuning. Stored procedure taking too much time to respond

Mysql stored procedure taking too much time after migration to new server. Stored procedure taking too much time to return results. My cnf file as follows [mysqld_safe] socket = /var/run/mysqld/mysqld.sock nice = 0 [mysqld] user =…
rakesh pakkam
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Check performance of ETL in SSIS

How can I check how long it lt took to extract data and load data in SSIS. I am using Attunity connector now for extracting Data from Oracle and then using OLE DB destination to load it in SQL Server. Using Attunity is not making any difference in…
Doodle
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Tuning mysql. Mysqltuner recommendations

Good afternoon. The site is located on VPS (10 GB RAM, 2 CPU core, 65 GB SSD). I want to improve the speed of the site. But I do not understand all the parameters of mysql. I wrote out the current mysql settings, as well as the mysqltuner…
Boroda32
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Postgresql performance - Index page hits

I run the following query to estimate the ratio of index pages read rom memory (buffer hits) to index pages read from disk select t.schemaname, t.relname as "Table Name", io_i.indexrelname as "Index Name", case when…
MaterialGirl
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SQL Server Database Tuning Advisor Blocking Issues

This is occurring during the end of the analysis when the DTA tries to drop the indexes it created. Unfortunately, with the database in use, this is causing terrible blocking issues. Is there a way to prevent this? Using SQL Server 2008
Brian
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Speeding up my cloudant query

I was wondering whether someone could provide some advice on my cloudant query below. It is now taking upwards of 20 seconds to execute against a DB of 50,000 documents - I suspect I could be getting better speed than this. The purpose of the query…
J Deane
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Oracle SQL query improves performance on second and third execution

We are analyzing sql statements on an Oracle 12c database. We noticed that the following statement improved by running several times. How can it be explained that it improves by executing it a second and third time? SELECT COUNT (*) FROM asset …
r0tt
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