10,938 questions
0
votes
1
answer
93
views
SQL query produced by Entity Framework very slow
I have the following query being generated by EF:
DECLARE @__term_0 VARCHAR(7) = 'woodrow'
DECLARE @__p_1 INT = 0
DECLARE @__p_2 INT = 15
SELECT [t].[Id], [t].[City], [t].[Contact], [t].[CreatedBy], [...
- 1,231
-1
votes
1
answer
86
views
Azure SQL S0 Tier – Slow Update Performance During Peak IoT Data Processing [closed]
I'm using Azure SQL (Standard S0: 10 DTUs) to store data from various IoT devices.
Each IoT device sends messages to my Azure IoT Hub, which then triggers an Azure Function App. The Function App ...
- 761
-3
votes
0
answers
24
views
Azure synapse analytics dedicated pool query view is running very slow [closed]
We have Azure synapse analytics dedicated pool database. Some of views are running versy slow. It takes more than 30 minutes to return the data. The problem is the view does not have any filter on it. ...
- 1
0
votes
2
answers
208
views
Why correlated scalar is 10x times slower in MySQL comparing to PG
Let's create a table with 3000 rows
create table tt(id int, txt text);
insert into tt
with recursive r(id) as
(select 1 union all select id + 1 from r where id < 3e3)
select id, concat('name', id)
...
- 653
3
votes
1
answer
187
views
Why does this query slow down this much over time
I'm testing with a very simple database queue to see how fast I can process it. At the moment without even doing anything else then just retrieving it from the queue.
A simple CTE query selects one ...
- 14.3k
4
votes
1
answer
163
views
Why does 'Index Seek' read 20 million rows for `select max(uk) from T where uk <= @x`?
In a table T with 20 million rows and a unique constraint on integer column uk, the following query induces SQL Server 2019 to perform a scan of all index entries instead of a single seek:
select max(...
- 4,825
1
vote
1
answer
87
views
MySQL 8 runs very slow when including a NOT IN in the where clause
I have a website that displays on the main page the 12 latest uploads from the site's users. In that query, users can filter out uploads from certain other users (hence the NOT IN clause). Here is an ...
- 61
-1
votes
0
answers
75
views
Timeout or Data not fetching in SQL Server [duplicate]
I have an ASP.NET Core MVC application with SQL Server, both the servers are hosted separately but in same VPC on AWS. Application runs smoothly and no connection timeout is received for the reporting ...
2
votes
2
answers
168
views
MySQL: Writing better compound indexes
I recently came to know about the performance boosting capabilities of using compound indexes or composite keys in mysql through this question of mine Create multi table index/composite key.
After ...
- 2,035
1
vote
0
answers
34
views
Multiple language labels in sparql query on wikidata
I want to query wikidata entities and their labels in multiple languages. But for some reason querying the labels is very inperformant.
My base query looks like this (find 3 life forms that have ...
- 830
1
vote
1
answer
67
views
SQL - Adding Union All on derived table subquery fetches all rows
Attempting to optimize a portion of a query that is joining two related tables, and getting odd results compared to other queries in the project with similar structures. Here is a very simplified ...
- 11
3
votes
1
answer
101
views
What is the optimal BigQuery SQL query to group the same data multiple times over different groups?
I have a very large BigQuery table with web events that I want to aggregate into daily, weekly and monthly numbers of visitors. And I want to join them into the same table.
My initial guess is to do ...
- 35
2
votes
2
answers
134
views
Query with aggregate functions is very slow
I have the following query:
WITH RankedCallNotes AS (
SELECT
Id,
CreatedOn,
CandidateId,
Text,
ROW_NUMBER() OVER (PARTITION BY CandidateId ORDER BY ...
- 1,231
0
votes
1
answer
79
views
Implementing CASE-WHEN or Aggregations in Materialized Views in BigQuery
I have the below mentioned BigQuery SQL for a View. However, both the tables used in the query are huge in volume and hence I am facing terrible performance issues.
If you'd glance at the query, I am ...
- 895
0
votes
1
answer
143
views
Querying tag values at specific event times efficiently
I have an event tag that logs events, and a temperature tags that records data every 0.5 seconds. I want to know the temperature at the start of each event.
I'm using Microsoft SQL Server Management ...
- 35