Why is the query so slow in PostgreSQL?

Why is the query so slow in PostgreSQL?

But if I embed it into a function, the query runs very slow through all data, seems that is running through every record, what am I missing?, I have ~1M of data and I want to simplify my database layer storing the large queries into functions and views.

Why is MY SQL Server database too slow?

Can you help me setting al troubleshooting steps I shoud do in order to determine why my SQL Server database (2012) is too slow! Since the past two days, all our databases began to get too slow, even some queries and processes ended with a timeout error. The CPU, disk and memory of the server usage seems normal.

Why is SQL Server sending data faster than my application can consume?

(They are misleadingly named) It’s usually a client app that cannot consume data fast enough. i.e. SQL server is sending data faster than your application can consume. Culprits are often client apps that process data row-by-row.

Is it slow to redraw data in SSMS?

SSMS can be quite slow to redraw data. With this option set, SSMS will read all the data off the wire, but it won’t show you the data. This will enable you to run queries at the speed that SQL server can run at and not be crippled by the client application speed.

How to get better performance with PostgreSQL-SQL function?

If all your calls only return (in the vicinity of) 2 rows, just declare that with an added ROWS 2. Might change the query plan for the VOLATILE variant as well (even if STABLE is the right choice anyway here). You will get better performance by making this query dynamic and using plpgsql.

What causes a sub optimal query in PostgreSQL?

If any of these internal statistics are off (i.e., a bloated table or too many joins that cause the Genetic Query Optimizer to kick in), a sub-optimal plan may be selected, leading to poor query performance.

How long does it take Postgres to respond to a query?

In 99.9% of accounts these queries would be zippy. In a few cases where the number of tags used to annotate metrics is large, these queries would take up to 20 seconds. That much time spent in a database meant that someone was waiting in front of their browser for the graph editor to respond.

Can a Postgres optimizer push down a view?

The Postgres optimizer (and the optimizer for many other modern DBMSes) will be able to push down predicates on the view into the actual view statement – provided this is a simple statement (again, this can be verified using explain analyze).

Is it bad to use views in PostgreSQL?

Views are typically useful for speeding up the development process but in the long run can completely kill database performance. The following is an excerpt from PostgreSQL 9.5 Documentation: Making liberal use of views is a key aspect of good SQL database design.

How many rows does a function return in PostgreSQL?

Since you didn’t define otherwise, the function assumes an estimate of 1000 rows to be returned. But your function is actually returning only 2 rows. If all your calls only return (in the vicinity of) 2 rows, just declare that with an added ROWS 2.

How to identify performance issues with slow queries?

If we are talking about interactive applications, most likely anything slower than a second is noticeable. Ideally everything is executed within 100 – 200 milliseconds limit. Once we determine that given query is indeed something we want to improve, we should take a look at the query execution plan.

What to do if PostgreSQL is not logging?

If you do not see any logs, you may want to enable logging_collector = on as well. The logs will include all of the traffic coming to PostgreSQL system tables, making it more noisy. For our purposes let’s stick to the database level logging. ? You can see information about the query and its duration.

Why is Sow performance slow in SQL Server?

In my case in DB table column type was defined as VarChar and in parameterized query parameter type was defined as NVarChar, this introduced CONVERT_IMPLICIT in the actual execution plan to match data type before comparing and that was culprit for sow performance, 2 sec vs 11 sec.

When does SQL match index against query plan?

When SQL starts to optimize the query plan for the query with the variable it will match the available index against the column. In this case there was an index so SQL figured it would just scan the index looking for the value.

How to improve query speed in SQL Server?

Instead I converted the view into a User-Table-Function where the parameter was the value needed on the WHERE clause. In fact this WHERE clause was nested 3 queries deep and it still worked and it was back to the < 10ms speed. Eventually I changed the parameter to be a TYPE that is a table of UtilAcctIds (int).