Complex SQL window function limitations

“How do I find what's causing a task to be slow, when CPU, memory, disk and network are not used at 100%? I'm currently analyzing a process that is considered too slow. In summary, it's a task that loads a lot of data from Microsoft SQL Server, performs some basic stuff on it, and creates a report. It currently takes from five to six hours, whereas the stakeholders expect it to take three to four hours. Basic analysis showed that: The application server that runs the actual task is underused. The”

“"Aggregate functions are not allowed in recursive common table expression" - but actually, they are? I have table of structure data in SQL Server. I want to travese the tree and find all nodes with a recursive query. Additionally, the structure data is versioned. I want to always use the latest version, and ignore other branches. To do this, I need to use a sub-query with an aggregate function like MAX(version), or a cross apply with TOP 1 version. But these are not allowed in recursive queries,”

“Get SQL result with previous and next row I want to add to my result rows the immediate previous and following row according to a specific clause. Simplified case: ROWID value x level 0 1.0 0 1 1 2.0 1 2 2 3.0 2 1 3 4.0 3 2 4 5.0 4 1 5 6.0 5 2 Query: [code] This query returns: [code] How do I add the immediate previous row respecting the clause [code] and add the immediate following row which respects [code] ? I'm expecting to get: [code] [code] and [code] window functions compute a new column i”

“Postgres not using indexes when checking for nulls I have two tables. They each have around 2.3 million rows in them. They are running on PostgreSQL 17.4 [code] I want to delete values from the audit table if the following 2 requirements are satisfied: update datetime is past a certain date there is a row with identical keys in keyeddata (or keyeddataaudit, I don't mind which) with a higher version The idea is to delete old values, but only if there is a more recent one. I can get the same perfo”

“Mysql performance issues we have some tough performance issues that seem to us that they shouldn't exist, but we don't see any way of solving them. We have a Gcloud Mysql database, with 4Cpu, 16go Ram. The full instance contains around 50Go (on ssd) but our main database only 15Go. We get extreme slowdowns on most pages of our app in the middle of the day, when it is the most used. With some pages taking 40s (or more) to load. We've extracted the queries and by themselves they take 'only' around”