Added new troubleshooting guide on how to run explain analyze on functions

apps/docs/content/troubleshooting/running-explain-analyze-on-functions.mdx

@@ -0,0 +1,60 @@
+---
+title = "Running EXPLAIN ANALYZE on functions"
+topics = ["database", "functions"]
+keywords = [] # any strings (topics are automatically added so no need to duplicate)
+
+[api]
+sdk = ["rpc"]
+---
+
+Sometimes it can help to look at Postgres query plans inside a function. The problem is that running [EXPLAIN ANALYZE](https://www.depesz.com/2013/04/16/explaining-the-unexplainable/) on a function usually just shows a [function scan](https://pganalyze.com/docs/explain/scan-nodes/function-scan) or result node, which gives little insight into how the queries actually perform.
+
+[auto_explain](https://www.postgresql.org/docs/current/auto-explain.html) is a pre-installed module that is able to log query plans for queries within functions.
+
+Auto_explain has a few settings that will need to be configured:
+
+- `auto_explain.log_nested_statements`: log the plans of queries within functions
+- `auto_explain.log_analyze`: capture the `explain analyze` results instead of `explain`
+- `auto_explain.log_min_duration`: if a query is expected to run for longer than the setting's threshold, log the plan
+
+Changing these settings at a broad scale can result in excess logging. Instead, one can change the configs within a `begin/rollback` block with the `set local` command. This ensures the changes are isolated to the transaction, and any writes made during testing are undone.
+
+```sql
+begin;
+
+set local auto_explain.log_min_duration = '0';       -- log all query plans
+set local auto_explain.log_analyze = true;           -- use explain analyze
+set local auto_explain.log_buffers  = true;          -- use explain (buffers)
+set local auto_explain.log_nested_statements = true; -- log query plans in functions
+
+select example_func(); ---<--ADD YOUR FUNCTION HERE
+
+rollback;
+```
+
+If you find it necessary, you can change these settings for specific roles, but it's not recommended configuring the value below `1s` for extended periods, as it may degrade performance.
+
+For instance, you could change the value for the authenticator role (powers the Data API).
+
+```sql
+ALTER ROLE postgres SET auto_explain.log_min_duration = '.5s';
+```
+
+After running your test, you should be able to find the plan in the [postgres logs](https://supabase.com/dashboard/project/_/logs/postgres-logs?s=duration:). The auto_explain module always starts logs with the term "duration:", which can be used as a filter keyword.
+
+You can also filter for the specific function in the [log explorer](https://supabase.com/dashboard/project/_/logs/explorer?q=select%0A++cast%28postgres_logs.timestamp+as+datetime%29+as+timestamp%2C%0A++event_message+AS+query_and_plan%2C%0A++parsed.user_name%2C%0A++parsed.context%0Afrom%0A++postgres_logs%0A++cross+join+unnest%28metadata%29+as+metadata%0A++cross+join+unnest%28metadata.parsed%29+as+parsed%0Awhere%0A++regexp_contains%28event_message%2C+%27duration%3A%27%29%0A++AND%0A++regexp_contains%28context%2C+%27example_func%27%29+--%3C----ADD+FUNCTION+NAME+HERE.+IS+CASE+SENSITIVE%0Aorder+by+timestamp+desc%0Alimit+100%3B) with the below query:
+
+```sql
+select
+  cast(postgres_logs.timestamp as datetime) as timestamp,
+  event_message as query_and_plan,
+  parsed.user_name,
+  parsed.context
+from
+  postgres_logs
+  cross join unnest(metadata) as metadata
+  cross join unnest(metadata.parsed) as parsed
+where regexp_contains(event_message, 'duration:') and regexp_contains(context, '(?i)FUNCTION_NAME')
+order by timestamp desc
+limit 100;
+```