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Questions tagged [performance]

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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mysql simple update with 40 million and 128GB RAM taking too much time

We are having trouble with simple updates on a single table taking a long time. The table contains ~40 Million rows. and the job runs every day that truncates the table and inserts new data from ...
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2answers
52 views

Poor SQL Server Performance With Nested “OR” Conditions In LEFT OUTER JOIN

I have a tricky bit of SQL that's giving me a bit of trouble. I'd like to introduce several new columns to a key table whose components may or may not be used based on user configuration (Dimension's ...
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0answers
19 views

what is the overhead of Mysql database users [on hold]

i have one application where we wish to create new connection for all users so everything is new for all means , new database, new mysql users everything new but is it a good practice. we are doing ...
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1answer
26 views

Hi all, I am not getting the proper result set as shown below [closed]

There are two tables tbl_sales_hdr and tbl_sales_ftr. I am struggling to get the results as shown below. Please help me to arrive at this kind of result set. tbl_sales_hdr date inv_no ...
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29 views

RAC DB Slowness - AWR Report

While going through the AWR report found that the row lock waits on indexes and buffer busy waits are more (rest of the stats look normal). Could someone tell me if we can interpret by the below if ...
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What does 'innodb_buffer_pool_reads' and 'innodb_buffer_pool_read_requests' actually mean?

Mysql version: 5.7.18 (Innodb) I have a table with the following specification Structure: CREATE TABLE `dummybigint10` ( `pk` int(11) NOT NULL AUTO_INCREMENT, `name` varchar(255) DEFAULT 'A ...
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1answer
21 views

Performance: storing list of thousands of items in postgresql's JSON field vs having separate table for items?

Let's say I have some table A which have json-field items: A: foo: 'foo' items: [ {a: 1, b:2}, {a: 3, b:4}, ... ] There could be couple of thousands of items in one A object. Is there any ...
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12 views

Still getting values for performance_schema.global_status after setting 'Performance_Schema' to OFF

In mysql version 5.7, I have turned off performance schema (performance_schema=OFF in /etc/my.cnf), but still getting values incremented for variables in 'performance_schema.global_status' table. Why ...
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39 views

Creating index on a big text column in postgres

We are talking about postgresql 9.5 on windows with a database which has UTF8 encoding and "English_United States.1252" (default) LC_COLLATE and LC_CTYPE. The column is of type text and it is used ...
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15 views

Postgres - Storing Attributes in 1:0 related object, performance improvements?

In my DB's central table, "Profiles," I want to collect activity statistics that will be updated often, although not all profiles will have statistics. The "Profiles" table is already heavily updated ...
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1answer
21 views

How is it possible that a key of char+bigint has better performance than key of bigint+bigint?

I would like to store some user related data into a table. The data is identified by MD5 hash. I have 2 options: option 1 - have a table with 2 columns: hash_id (unsigned bigint) and md5 (char(32))...
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How can I store data with unpredictable data types in a table?

I'm currently working on a Headless CMS project and was wondering what approach would be the best for storing "fields" data in the database. Basically, users would be able to create a content model ...
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1answer
57 views

PostgreSQL performance with (col = value or col is NULL)

This question deals with PostgreSQL 9.5 query performance. The table is: CREATE TABLE big_table ( id integer NOT NULL, flag bigint NOT NULL, time timestamp with timezone NOT NULL, val ...
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1answer
30 views

Should I create seperate referenced table or go with serialized data in a column?

I have a table with name app_client with the below fields id, user_id, name, age, phone, gender, related_entities_json (long text datatype), created_at, updated_at I have 200k+ records in this ...
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40 views

How to increase Mysql 5.7 Performance?

We are running production slave database with 3 TB data in MySQL running on Azure VM with server configuration of 16 core and 32 GB. The major challenge is regarding over all MySQL performance. please ...
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2answers
90 views

Sql Query Performance

I have one query for the report. Query Use RIS select CİHAZ,sum(sayi) as [Çekim Sayısı], count(*) as [Hasta Sayısı] from (select CİHAZ,[KABUL NO],[TC NO], count(*) as Sayi from (SELECT a....
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2answers
41 views

Tuning mysql 5.7.1 for predominantly write workload on huge partitioned innodb tables

I recently got a task to tune MySQL for predominantly write workload on multiple innodb tables which are huge and partitioned. About the application: It's Nimsoft suite, so the SQL queries are not ...
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1answer
34 views

Performance of mysql equi-join observed in HDD and SSD

I experimented performance of queries having equi-joins. I have simplified version of EXPLAINs of the queries. Mysql version : 5.7.18 Engine : Innodb Cache state : Mysql restarted before experiment ...
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1answer
35 views

One vs. Many Tables for Frequently but Asynchronously Updated Columns?

As part of my Postgres 10 schema, I have two tables; current and historic -- both have the same columns. current has about 20 (+/-) columns, and holds the most up-to-date information for accounts. I ...
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2answers
65 views

What happens when sga and pga reach limits?

I have the following doubt, I have a server with Oracle 9i and another with Oracle 12c, in both cases I have the doubt that happens when Oracle reaches the limit imposed by the defined memory ...
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2answers
50 views

Slow Performance of SQL Server Database [closed]

I have a SQL Server Database, In two weeks in each four months many insert operation is executed to the database and in this time the database experience very slow performance, it takes a lot of time ...
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1answer
27 views

Postgresql responses are slow without internet

I have a Postgres service in Centos 7 and it works normally. Each time when the internet service (by an IPS) is down, the responses are slow, other times the DNS is reset by an electrical trouble, ...
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1answer
31 views

Using a caching tool for a remote database

When the DB is on a remote server, is there any tool to cache frequent queries on the main server in order to reduce database connections? If there are any available, what features should I consider ...
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1answer
57 views

Could a busy database affect others on the same server? [closed]

I have a very busy database with lots of reads and writes. I want to create another database on the same server, but I am wondering if that busy database will slow down the performance of the second ...
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1answer
21 views

SQLite how to store translations

Im looking for advise because my experience is not really good in SQLite. My table look like this: CREATE TABLE IF NOT EXISTS Route ( id integer PRIMARY KEY UNIQUE AUTOINCREMENT NOT NULL, name ...
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2answers
564 views

Is there any difference between a predicate using a literal value or a parameter value when that value will always be the same?

I have a query that always filters on a status, is there a performance benefit of one of these ways over the other? (This is in the context of an ad-hoc query. The datatype of UserStatus is int) ... ...
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1answer
80 views

Poor temporal table performance on older values

I'm encountering a strange issue occurring when accessing historical records within a temporal table. Queries that access the older entries in the temporal table via the AS OF sub-clause take longer ...
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1answer
49 views

CPU and Hard Drive Spike for 20-30 Minutes

I'm collecting data on the performance of our Microsoft SQL 2008 server in preparation for moving it to Azure. It's a very low load server (currently max concurrent transactions max out at 3), ...
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0answers
32 views

Poor query planning in Postgres 10

The query planner in Postgres10 seems to be ignoring the fact that my tables are clustered. I have to explicitly put "hints" in my query to have it perform the correct type of join. Here's my ...
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1answer
54 views

powerful VPS but slow MS SQL- why? [closed]

VPS (Contabo) : 10 cores (Xeon E5 2.2GHz), 60 GB RAM, SSD, MS SQL Web Edition (configured to use 10 CPUs), Windows Server 2016 When running SQL takes ~32GB of RAM, When I execute SQL a stored ...
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0answers
42 views

User permission businness logic

This question will also be posted in the stackoverflow, since dba and programmers may have different opinions. First of all sorry for the long question, but I wrote some extra code so that I can ...
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1answer
23 views

What index strategy to use to improve multi-condition SELECT?

As far as I understand, indexes should be selected on fields with high cardinality of data - e.g. sex only has two values ( male and female ) so low cardinality, whereas something like sha256sum field ...
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3answers
31 views

Linking Waits to a process/statement

I'm starting to take on more of a DBA role and trying to get tooled up with scripts and knowledge to help with this. I have been trying the sp_blizt procs in a dev environment. A key area I'm trying ...
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1answer
43 views

Does an index improve the querying performance in just two ways? [closed]

As far as I know, an index improves the querying performance in the following two ways: The index only contains the values of the column that it was created for and pointers to the rows in the ...
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2answers
167 views

Clustered Sequential GUID Primary Key vs Non-Clustered GUID and Clustered Sequential ID Primary Keys

I'm trying to figure out what the optimal solution is in regards to size and performance when using GUIDs as a primary key. The main reason for wanting GUIDs is that it's more appropriate in our micro-...
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1answer
74 views

Improve Performance on GROUP BY - large table PostgreSQL

I have a Postgres table containing the following three columns: origin (INT, b tree index) destination (INT, b tree index) minutes (SMALLINT, b tree index) The table has ~ 1.4 billion rows. Each row ...
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1answer
45 views

Mongodb as a data ware house?

Will mongodb a good choice as a data warehouse considering following situation? We are building analytics, report generation platform for our client and a typical table growth in terms of rows will ...
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1answer
90 views

PostgreSQL ANALYZE execution time over 24h (still running)

I upgraded a Postgres DB 9.3.2-->10.5 using pg_upgrade (in place). I did everything according to the documentation and the instructions given by pg_upgrade. Everything went fine but then I realized ...
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1answer
45 views

BETWEEN query on two indexed columns exponentially takes longer on minimal changes to LIMIT

This is a minimal example of my problem, but I reproduced the problem with this structure. I have the following table: | column name | type | |----------------+-------------| | id ...
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2answers
31 views

Mp3 file directly in a Database Without using BLOB [closed]

I need to store Mp3 files in a Database. Problem is that the files are going to be accesed with a smartphone. As the Smartphone is going to need to decode the Blob it would be very slow. I tried ...
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1answer
50 views

Loading 400 Million Records into MySQL Hangs on “Sending Data”

I have a large dataset of approximately 420 million records and I was able to load them into a temporary table in a timely manner of about 15 minutes using a LOAD DATA INFILE statement. Super awesome. ...
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0answers
28 views

LDF file size is very huge even after doing Transaction log backup [duplicate]

I work on a SQL Server 2016 Database and in our production environment we have primary SQL server and a fail over SQL server. All the transactions are occurring on the primary SQL server. In primary , ...
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1answer
65 views

REINDEX or REBUILD the indexes of a table after truncating it and then repopulating it?

Is it necessary to REINDEX or REBUILD the indexes of a table after truncating it and then repopulating it? I have a table with approximately 3.5 million rows in Oracle. Every week new data is ...
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1answer
33 views

Database schema tracking patient stats over time

I want to create a database which allows to record patient reading data points like: weight, height, pressure, etc., over time. I found a database schema like the one discussed in this Q & A ...
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2answers
33 views

MariaDB instance in cloud hit 95% CPU utilisation for 30 mins

I've got MariaDB instance in the cloud which I put live about 2 months ago. I'm new to the DBA business and I got the impression the people at the company who I run it through are learning on the hoof ...
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1answer
47 views

Disk block size for mongodb deployment

Why does Mongodb production notes have no recommendations about the disk block size? AFAIU, disk block size would have a considerable impact on a throughput intensive application. Does disk block size ...
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1answer
27 views

SAP BO Freehand SQL date formatting (Oracle db)

My original query worked perfectly via SQL Developer: select * from [table] where DT_CURRENT_DT = '15-OCT-18' However when ran via freehand SQL in SAP BO I got no results. After running the query ...
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1answer
31 views

What happen when a transaction is committed and SNAPSHOT isolation is enabled?

I am actually considering using SNAPSHOT isolation for one WCF service. Before doing so, I would like to know how it works. AFAIK, when it's enabled, updated rows are maintained in tempDB (instead of ...
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1answer
17 views

Does number of backup tables hinder performance

Our main database (MySQL) has about 50 tables with about 2 million records each, many of the columns are indexed. Before doing any major change, we either copy the entire DB under a new name like "...
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1answer
61 views

What database to choose for 1TB of time series? [closed]

I'm saving about 3GB per day of financial orderbook data to a database (currently Mysql). In the coming weeks, I'm going to save trade and quote (bids/asks) data too. Data is structured, but I'm ...