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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index corrupt error while trying to index a large table

I am trying to index a large table, approximately 12 million rows and 33GB in size. There is currently no indexing on the table. When I am trying to index one of the columns in a table, I get the ...
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22 views

Improve MySQL INSERT performance for MEDIUMTEXT

We are running a MySQL Innodb database, our server has 4gb memory. We are trying to improve the speed at which a 800KB XML File is stored in a MEDIUMTEXT column. Currently, we have this query ...
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MongoDB insert data if not exists and update only the array if exists on large amount of documents

So I have about 1M records to first insert and then subsequently update an array in them whenever I run the script. A typical record { "_id" : Object(), "id" : "my_unique_id", ...
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41 views

SSIS Slow Data Transfer between Oracle and SQL Server 2016

I am trying to design a process that transfers data from Oracle to SQL Server 2016 by using SSIS. It is done with the aim of removing productive processes from an SQL Server 2000 instance, where the ...
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usage percentage of Mongodb internal cache

I've ran two performance test on a MongoDB server with identical environment/settings AFAIK. I found that the throughput was 10% apart. When I inspected the mongostat logs, I found that Mongodb in ...
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Need help on designing database schema for high frequency update app

This app will call API endpoints every second and get JSON data and it needs to be saved in DB and then query it to the client. But Before saving, it needs to check if the data already exists or not, ...
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1answer
57 views

Quasi-Lateral Partitioning [on hold]

I have a table that stores generic data for a wide variety of purposes that are almost totally independent of one another (created by different users for example). So I'm thinking about adding an ...
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1answer
64 views

Is it useful to index a column if it is already the first column in a composite index? [closed]

Suppose I have this table (simplified from my project): create table BillTax ( BillID int not null constraint FK_BillTax_Bill foreign key references Bill(BillID), TaxCode varchar(20) not null,...
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2answers
48 views

Unable to retrieve query plan of running query because of blocking

I am trying to troubleshoot a long running query in a stored procedure that around once every month randomly runs for ever and never finishes. Probably some plan caching issue. But the problem is ...
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54 views

SQL Server: Explaining to C-Level Executives the impact of using Primary Key of VARCHAR(50) in many tables throughout a database?

Suppose a global, mid-sized company is considering a document control management solution that is backed by a SQL Server database and allows developers to create document form types using a form ...
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Is Network I/O included in the timings for “RPC complete” seen in SQL Profiler?

When watching results in SQL Profiler, does the RPC Complete include time to send results to the client? Or is it just the time the server spent gathering the records? The reason I'm asking is I'm ...
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20 views

oracle decreasing vs increasing column varchar2 performance

I know it seems stupid question but why increasing the column of a table tend be fast but decreasing it takes time depend on the size of the table? Is it because while decreasing oracle check each ...
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Percona: Analyze table doesn't work

I have a Percona 5.6.28 servers with a=some TokuDB tables. The biggest table has ~120 million rows. Statics keeps changeing in the past hald year: At first. Analyze table with recount model toke ...
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1answer
33 views

Performance Recommendations for Large Volume of Data

Oracle Table: Fields: 55 Roughly 10 are Used for Querying Single Record Length: 512 bytes Records: 3-5 million records per day Period of Time: 13 months to be available, > 13 months to be purged ...
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SQL Server suddenly using a lot of CPU: 300 compilations/s vs 2 batches/s

A instance of SQL Server Express 2016 that I'm in charge of has suddenly started to use a lot more CPU that usual. It's the backend database for a website, but doesn't see all that many queries due to ...
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Does a read replica help if the problem are heavy queries?

The application that our team is responsible for is having ever more often DB performance problems. The application querying it doesn't throw lots of concurrent queries, the problem we have are rather ...
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3answers
500 views

How likely is fragmentation on a table with 40000 products likely to affect performance

So database administration is not a strong point of mine, so I have a few questions. This all relates to the performance of a website I'm looking at, and have spent a fair bit of time researching/...
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50 views

How to reduce the response time of a query that yields ~4.9 million rows in ~12-13 seconds

I have the following doubt about the execution performance of a query. This query takes about 12-13 seconds, and brings a total of 4,879,049 rows. Could I lessen this query's response time? The query ...
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27 views

How to implement complex search functionality?

Below is my table structure: CREATE TABLE `post` ( `postId` bigint(20) NOT NULL AUTO_INCREMENT, `userId` mediumint(8) unsigned NOT NULL, `areaId` smallint(5) unsigned DEFAULT NULL, `postTitle`...
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57 views

Postgresql 11 - slow insert performance when table reaches ~5 million records

I have a table with ~6 million records that gets loaded on a postgresql instance in a small machine (with standard PC HDD). It seems to be a I/O problem, since there are free memory and processing ...
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56 views

Linked Server Performance

I have three MS SQL Servers, 2016. 1 source and two destinations. There is a linked server setup from each destination server to the source. We execute a simple select query from each destination ...
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1answer
32 views

Performance Monitor % Processor Time metric difference between _Total and sqlservr.exe

I have SQL Server running on 32-core CPU, and I use Performance Monitor (perfmon.msc) to collect data on Processor: % Processor Time (Instance - _Total) and Process: % Processor Time (Instance - ...
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53 views

Int for identity/primary key and Guid for public identifier, best practices?

I almost always use an int for identity/primary (auto incrementing) clustered key for my tables. They're easy to query and debug, bounce around in SSMS, and plenty of other reasons. I have a case ...
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21 views

Options and best practices for Multiple Result Sets in Postgres11

I want to get two (small) result sets and have the benefit of precompilation and 1 round trip to the database. SQL Server allows a stored procedure to contain multiple select statements. SELECT u....
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2answers
29 views

Replacing IN condition in Oracle

Oracle here. I have the following tables: [orders] === order_id : integer constraint pk_orders primary key using index order_name : varchar2(40 char) order_ordered_by : integer constraint fk_shoppers ...
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Proc runinng slow once in a while [duplicate]

I am trying to troubleshoot the performance issue on one of the SP which executes throughout the day daily every 20 mins and on avg completes under a min. For past couple of weeks it happens once in ...
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3answers
152 views

Replace column by LEFT OUTER join to save space

I have a table t1 with 100M row. For column A, 95% of the rows have value NULL0, the other records have values from 1 to 9. To shrink my table, I'm thinking about moving column A to table t2. t2 ...
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24 views

Mysql high number of queries in queue

we have been struggling to understand this behabiour on mariadb. we have some jobs that run every minute and they do a lot of updates on some metadata tables inside mariadb, however we have noticed ...
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15 views

How does the MongoDB $filter (aggregation) stage work internally?

I was asked a question by a colleague today whether the MongoDB $filter aggregation stage is implemented efficiently. The aggregation stage in question: $project: { absences: { $filter: {...
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19 views

optimize query with date type field in mysql

I currently have the following query prepared: select sum(amount) as total from incomes where (YEAR(date) = '2019' and MONTH(date) = '07') and incomes.deleted_at is null When ...
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47 views

Database performance, tps & IOPS

We have a Java application that uses a MariaDB database that is dedicated to this application. The application needs to insert 1 million records within 5mins so ideally we would like the database to ...
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Database performance, tps & IOPS [duplicate]

We have a Java application that uses a MariaDB database that is dedicated to this application. The application needs to insert 1 million records within 5mins so ideally we would like the database to ...
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22 views

Mysql memory_global_total is smaller than memory usage in top [duplicate]

When I try top in my ubuntu the result top - 16:03:09 up 16 days, 21:24, 2 users, load average: 3.53, 2.72, 3.46 Tasks: 395 total, 1 running, 282 sleeping, 0 stopped, 0 zombie %Cpu(s): 10.0 ...
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Possibility of using self-referential foreign key to create hierarchical comments

I am an accidental DBA and have a question regarding the table structure of a website I maintain (postgresql 9.6 backend). Imagine a typical content website (let's call it 'Links'), where users post ...
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2answers
111 views

MS SQL Server Performance Issues After Enabling All CPU's [closed]

My system specifications are; Windows Server 2008 R2 Enterprise SP1 128 GB RAM Intel Xeon E5-2620 (3 processors) MS SQL Server 2012 Standard (11.0.2100.60) There is 3 NumaNodes and 12 CPU's in them. ...
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1answer
28 views

Advantage of 'with' queries over plain 'select' and joins?

Are there any advantages using WITH queries instead of simple SELECT queries using JOINs performance wise? I am asking solely about reading data (from catalogues specifically).
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SQL Server database slow performance [closed]

I have a SQL Server database in production, and typically the performance of the application connected the database is satisfying. For some days many clients were complaining about slow performance of ...
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1answer
22 views

MongoDb Join VS Nested Query

I'm trying to build a game server and we are using MongoDb as the database. We have a collection Games that has models like this: { "_id" : ObjectId("5d1b345b8ea742034db76431"), "Users" : [ ...
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1answer
33 views

How does 'Top SQL - By Application' values from SQL sentry correlates

I have run a performance simulation on my application server and pull the sentry report for my analysis. And While going through the top sql -by application, I found difficult to correlates the values ...
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24 views

Revenue Forecast Database Design

I am currently trying to design an Access database that will house financial data containing forecasting, actuals and prior forecast data. The current format of the Excel "database" is Customer ...
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2answers
58 views

MySQL - Got an error reading communication packets - high open tables, server goes offline

I am currently testing a product with a couple of my friends before releasing to the public. There's now 10 of us who use the application daily. Yesterday, we noticed a performance error on the MySQL ...
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1answer
38 views

MySQL using more memory than expected

We recently upgraded a database server from Ubuntu 14.04 to Ubuntu 18.04, and at the same time upgraded MySQL from 5.6 to 5.7. Since the upgrade, the memory usage has more than doubled, from ~10GB to ...
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1answer
30 views

Detect bottleneck of server via psycopg2

I have PostgreSQL superuser called "admin" which can connect to a PostgreSQL database. I am not managing the database server. I have no root-access to this machine. Sometimes the performance is not ...
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23 views

How performant is finding a substring in database?

To route requests on my website, I need to query the database to see if the first part of a URL matches a category for an item. For example: I have a request to /animals/dog/darktheme/. The ...
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1answer
54 views

Help using SQL Server Database Experimentation Assistant for performance testing

I am following the guide for capturing a trace in SQL Server Database Experimentation Assistant here: https://docs.microsoft.com/en-us/sql/dea/database-experimentation-assistant-capture-trace?view=sql-...
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4answers
109 views

Indexing a SHA hash in place of a VARCHAR

In Is it a good idea/approach to index a VARCHAR column? the concept was using VARCHAR as the column. I was wondering, if we store the SHA-1 hash or SHA-256 hash (if I am paranoid) as a BINARY(20) ...
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MySQL Percrona 8.0 became suddenly slow until restart mysql

My website today suddenly became slow and all requests were taking about 2 seconds to complete. Usually it takes like 0.2 second I checked available space on disk and I have a lot. Memory and CPU ...
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138 views

Very similar queries, vastly different performance

I have two very similar queries First query: SELECT count(*) FROM Audits a JOIN AuditRelatedIds ari ON a.Id = ari.AuditId WHERE ari.RelatedId = '1DD87CF1-286B-409A-8C60-3FFEC394FDB1' ...
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33 views

What DBMS to choose for my production environment? [closed]

This is my very first question on the StackExchange/StackOverflow community. I originally am an electrical engineer so I hope you bear with me. I need to set up a database whose purpose is to be ...
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1answer
60 views

SQL Server performance with FREEPROCCACHE [closed]

I watched a lesson on Youtube about SQL Server performance tuning. They demonstrated on a query "Wait Time per Core Per Sec". They use an update script as below: DBCC TRACEON(4199,-1); DBCC ...