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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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Automatic index creation - too many

When we have the auto tuning set to ON for index creation, the Azure SQL Hyperscale db has created about 10 indexes for some of our large tables. In analyzing the indexes, some of them differ only in ...
Anand Sowmithiran's user avatar
0 votes
1 answer
86 views

why CREATE DATABASE FOR ATTACH too slow in parallel?

For testing purposes, I created 15 different .mdf files that are essentially the same file (300MB) but with different names. When I use CREATE DATABASE FOR ATTACH for a single database, it takes about ...
Obscure_33's user avatar
0 votes
1 answer
30 views

Manage the amount of data on tables

I can have several tables with 10+ millions rows in by year. I would to know what's the best approach to maintain responsiveness with this amount of datas and I have two ideas. Don't touch these ...
Matt's user avatar
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0 answers
42 views

Random long writes (waiting for handler commit)

I have some INSERT/UPDATE queries who takes a long time randomly. I try to launch the same INSERT several times with profiling enable. And I remark that the duration is always in waiting for handler ...
Matt's user avatar
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0 answers
12 views

Variable time execution for INSERT/UPDATE

I do an INSERT/UPDATE in a table who has around 1+ million rows in MySQL 8.0. I don't know why I have different execution times for the same data to insert. For example, I try to insert exactly the ...
Matt's user avatar
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0 votes
1 answer
50 views

best set of indices

This is a MySQL case with 5,000,000 records in trade table, and 5,000,000 records in registries table. little cases exist where uni is duplicate. i.e. values of uni is almost different. same comment ...
Ali Tavakol's user avatar
1 vote
1 answer
86 views

What is the impact on an index when I am widening a key varchar column

One of the central tables in my database has a varchar(25) column named EmployeeID. This column is used within a compound index and is likely the most used index in our system. We got an enhancement ...
Aheho's user avatar
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0 votes
1 answer
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Why does moving a postgres table from one tablespace to another take so long

Why does moving a postgres table from one tablespace to another take so long (and how can I speed it up) I have a postgres database with two main tablespaces, one on a SDD, the other on magnetic HDD. ...
ConanTheGerbil's user avatar
-1 votes
1 answer
67 views

How do I measure the SQL Database responsiveness

I am load testing my web app which is Azure App Server + Azure SQL Database. I am looking at the the Azure data dashboard metrics as we load test it and most measures (DTU percentage, CPU percentage, ...
David Thielen's user avatar
-1 votes
0 answers
27 views

postgresql insert performance using copy (python pipeline)

I was wondering if I can get your opinion on the performance of a simple data pipeline. it's all written in python, using pandas, and it essentially allows me to read all kinds of formats (parquet, ...
Chris's user avatar
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0 votes
1 answer
36 views

Is it any performance downgrade when query separate db (by db link) on same physical server

I have simple question but i could find any information about it. I also run some tests but didn't get any results that i measurable. Let say i have same structure with same data on my db and second ...
cargt3's user avatar
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2 votes
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Concurrent update to one record in same table created a deadlock between primary key and secondary index

Concurrent reqs under odd case has triggered the same update query twice which surprisingly led to deadlock between primary key and secondary index update in the same table. The update query will ...
kumarssk8's user avatar
1 vote
1 answer
50 views

Aurora Postgres - Database per Tenant architecture issues

We have a multi-tenant SaaS app. We had been using a shared DB for all our tenants with TenantId as foreign key in all the tables. Everything had been working fine, till our business required DB (or ...
adnan kamili's user avatar
0 votes
1 answer
59 views

high cpu spikes on postgresql (rds)

I have a PG 15(.5) RDS instance, which is experiencing intermittent random(?) periods of high cpu; that do not seem to, afaict, correlate with an obvious cause: Here is one example. The queries being ...
grahamrhay's user avatar
1 vote
4 answers
125 views

MySQL solution for many to many associative table that scale over billion entries

Scenario Imagine we have a table user and an item user. These 2 tables have an associative table called user_item to define a many to manyrelationship. We start 100 item records We have 500 Millions ...
Federico Baù's user avatar
0 votes
1 answer
31 views

Oracle temporary tablespace performance

I'm looking for ways to improve my database performance for heavy analytical queries and found that my temp tablespace has 1M extents (default for uniform tablespace). With my usual temp tablespace ...
Andy DB Analyst's user avatar
2 votes
0 answers
60 views

SQL Server Underestimating cardinality on a Filter operator in a Left Anti-Join

I am tuning a query which is slow, I have narrowed the root of the problem to be at the very beginning of the execution plan, where SQL Server makes a bad estimate on a WHERE IS NULL filter that ...
SE1986's user avatar
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1 vote
2 answers
115 views

Unable to enable Performance Insights on Amazon RDS db.t3.small instance

I recently upgraded my Amazon RDS instance from db.t2.micro to db.t3.small. After the upgrade, I also activated the performance_schema parameter in the associated parameter group because I've read ...
Igor's user avatar
  • 113
0 votes
1 answer
44 views

MariaDB Performance Degradation After Brief 20 Hour Massive Improvement

Problem On 2024-05-07 20:00:00 we migrated our DB from MariaDB 10.5 on an 8 core 16GB RAM server with a 10GB innodb buffer pool to a MariaDB 10.11 server with 16 cores 32GB RAM and a 20GB buffer pool ...
Joe Keilty's user avatar
4 votes
1 answer
123 views

PostgreSQL has stopped using index for large IN query?

I've got a large table (~2.2 billion rows), the table structure is basic: Column | Type | Collation | Nullable | Default | Storage | Compression | Stats target | ...
Zak123's user avatar
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0 votes
2 answers
80 views

How can I monitor query performance on my Azure read-replica database?

I'm looking at Query Performance Insight for my read-replica database. But the information it shows are the performance stats from the primary database. How can I get the performance stats for the ...
Yossi Geretz's user avatar
0 votes
1 answer
20 views

Do the vCores in my Read-Replica process the synchronization activity?

My initial understanding of my read-replica is that it would be less busy than the primary. After all, the primary is processing all the reads, inserts, updates and deletes which are supporting my ...
Yossi Geretz's user avatar
4 votes
2 answers
178 views

Index seeks and predicate push down

I have a query of the following form: IF EXISTS ( SELECT 1 FROM ( SELECT RowID, OETID FROM @InMemoryTableTypeTable i UNION ...
Dan Def's user avatar
  • 165
0 votes
2 answers
101 views

Performance issue - using try catch to return data to service & how to use partition table with unique index

I'm working on enviorment SQL azure. I've got a stored procedure that runs from several AKS simultaneously and insert a message. So it's a race for who writes the message first and the rest fails. The ...
dexon's user avatar
  • 47
0 votes
0 answers
90 views

High number of Latch Waits, is it a problem, and how to investigate?

We have reports of performance issues on one of our applications. I tried to have a look for anything obvious, but I'm an Oracle DBA, and my SQL Server knowledge is pretty limited - we don't have any ...
Carlovski's user avatar
  • 113
-3 votes
2 answers
102 views

Why is the performance of these two equal queries so different? [closed]

This specific query has an average return time of 3:40 minutes SELECT ROUND((SUM(ENF.TEMPO) / 24 / 60), 2) AS BROCHADEIRA FROM ( SELECT SZ9030.Z9_RECURSO AS COD_REC, ((ISNULL(TEMPO.TEMP, 0) + ...
Gabriel Pereira's user avatar
0 votes
0 answers
39 views

I increased my NDF files from 3 files to 7 files. How to re-distribute the data across MDF and NDF files?

I have a big database that uses 1 MDF files and 4 NDF files. The MDF file is placed in a 2TB disk and NDF files are placed in 500GB disks separately. I set the MDF file to be unlimited, while the NDF ...
Affan Widyan's user avatar
0 votes
1 answer
42 views

PostgreSQL & SQLAlchemy: Minimizing Impacts of latency with chatty applications

Are there any ways to minimize the impact of latency between the application and database when running PostgreSQL & SQLAlchemy ORM? Changing loading strategies or preloading properties has been ...
Justin Lowen's user avatar
0 votes
2 answers
73 views

High number of loops in within a nested loop Index Scan

Query SELECT organizations.lf_id, organizations.eb_id FROM organizations JOIN organization_lists_organizations ON organizations.id = organization_lists_organizations.organization_id WHERE ...
andrepcg's user avatar
  • 101
1 vote
1 answer
41 views

How to choose hardware for MYSQL Server in Azure - Flexible Server

I have a MYSQL Flexible Server in Azure with the following hardware configuration: MYSQL 8.0 Compute Tier: Business Critical - 16 vCores Size: E16ds_v4 Storage: 269 GB AutoScale IOPS RAM: 128 GB I ...
SakZepelin's user avatar
1 vote
1 answer
49 views

What does psql do on connect (that could be taking 1 to 10 minutes)?

In some cases psql is taking ~1 to 10 minutes to connect to PostgreSQL, with no queries that it seems to be running while doing so (according to pg_activity that I think queries pg_stat_activity) I'm ...
Michal Charemza's user avatar
0 votes
3 answers
97 views

How to best optimize computer for intensive Mysql queries?

I have a series of tasks I run in MYSQL 8 every day. Actually these tasks are run from a vb.net application that interfaces with MYSQL using 8 connections at a time. These tasks are a series of ...
Luke Krell's user avatar
1 vote
0 answers
36 views

Slow inserts into Azure PostgresSQL database

I have a simple table on what is basically a completely fresh database: create table import_test_uuid ( id integer not null generated by default as identity primary key, guid uuid ); I am ...
mohamedmoussa's user avatar
0 votes
0 answers
24 views

Mysql sharding in depth

I have a table that looks like this. Learning sql recently, USERID|MATCHID|TOURNAMENTID|SCORE|COUNTRY There are different tournaments running day to day and each tournament has many matches. some ...
umarkaa's user avatar
  • 37
0 votes
0 answers
26 views

Performance difference in SQL queries using JOINs with function

I have two SQL queries that are structurally the same, but have a significant difference in execution time. The first query takes around 500ms to execute, while the second one takes only 50ms. Both ...
Timon's user avatar
  • 33
0 votes
0 answers
33 views

Performance issue - cant fix with pg_plan_hints

I have a query that is stored in a function. It is called via a prepared statement jdbc app. I have a fix for the query to force an index - but I cant get the "normalized form" required for ...
captaintwocan's user avatar
0 votes
1 answer
56 views

Why adding a where on a well-know set of result increase the process time? [closed]

On SQL Server, if I do this query: select top(10) * from MyTable order by id desc it tooks only some ms to execute. (please note, every rows contains a field Message with value "Some Fancy ...
markzzz's user avatar
  • 243
0 votes
2 answers
78 views

Function performance is worse than raw query in PostgreSQL

I am trying to squeeze out the all the performance from my PostgreSQL database, also I want to abstract my query definitions from my application layer. To do that, I am using table-valued function. ...
vurqac's user avatar
  • 3
2 votes
1 answer
96 views

Can this subquery be optimized by a join? - Even without foreignkeys?

I have a table with two important columns: entity and enabled. The idea is that entities are "unique groups" where all rows with the same entity belong to the same "item". I wish ...
paul23's user avatar
  • 483
0 votes
0 answers
7 views

How to restore a backup and incremental backup of scyllaDB

I am working on incremental backup and restore. When I am trying to restore the incremental backup, after restoration, I am getting an error on cqlsh shell. ReadFailure: Error from server: code=1300 [...
MANJESH H S's user avatar
0 votes
0 answers
26 views

Purely in performance terms, how do CONTAINS([MyCol], 'foo') and [MyCol] LIKE '%foo%' compare?

Consider CONTAINS([MyCol], 'foo') and [MyCol] LIKE '%foo%'. Assume the best possible indexes on [MyCol], whatever those may be (at minimum, we need a unique key and a full-text index). I know that the ...
J. Mini's user avatar
  • 555
1 vote
2 answers
93 views

Recommendations to reduce table rows [closed]

I'm looking for some recommendations when dealing with tables with large number of rows. I have a table which has around 1.5 BILLION rows. Assuming there is a column ref_id. There could be 300K rows ...
Emmanuel Ponnudurai's user avatar
0 votes
0 answers
28 views

Deadlock - due to long transaction SQL server

I've got a stored procedure that runs 3 inner procedures all within a one BEGIN TRANSACTION. The environment is : Azure database sql as a result i have many deadlocks for the table : TranStatus. the ...
dexon's user avatar
  • 47
0 votes
1 answer
69 views

Metadata query slow on one specific database

I have quite a weird problem (who doesn't). Our ETL Software scans source databases to claim object data. It extracts information from INFORMATION_SCHEMA about objects (tables and views) SELECT t.[...
LonelyDBA92's user avatar
0 votes
0 answers
112 views

T-SQL Temp Table Performance Issue

At my current contractor job, I have come across something I have never seen before in SQL performance. There is a report that takes most of the day, or the entire day to run. Can return about 5 ...
user avatar
0 votes
1 answer
58 views

Index usage for NULL values

If there is index for a column, will it speed up search if condition is ... WHERE column IS NULL? In fact it is composite index on 2 columns and second column can be NULL (WHERE col1 = X AND col2 IS ...
i486's user avatar
  • 245
0 votes
0 answers
29 views

Temporary shutdown of autovacuum during rush hour

I have been asked to temporarily disable autovacuum in PostgreSQL 14.3. From 7 a.m. to 5 p.m., autovacuum is to be turned off, and at other times it is to be turned back on. I intend to achieve this ...
Patryk's user avatar
  • 1
2 votes
1 answer
261 views

MySql Aurora - how often to run ANALYZE TABLE?

I have a database that has existed for about 10 years, with hundreds of tables, many of which have several million rows. We don't have a DBA and we have an increasing number of slow queries. We're ...
mstrom's user avatar
  • 133
2 votes
1 answer
156 views

SSMS User Mapping Slow to Load, or Not Responding

I have been experiencing an issue in SSMS versions 14, 18, and 19, where loading the User Mapping of any given Login takes an age to load, sometimes up to an hour, or just never loads at all and hits ...
L.Moy's user avatar
  • 45
1 vote
0 answers
44 views

PostgreSQL - Star Schema - Execute plan seems "dumb" and i can't figure out why

I'm using a postgresql (15.5) database with the following logic: We have "meters" who measure electrical consumption. We have "computer meters" who are calculation of the ...
Sébastien De Wolf's user avatar

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