## Problem
Exporting `file_cache_used` which specifies the number of used chunks in
the LFC. This helps calculate LFC utilization as: `file_cache_used_pages
/ (file_cache_used * file_cache_chunk_size_pages)`
## Summary of changes
Exporting `file_cache_used`.
Related Issue: https://github.com/neondatabase/cloud/issues/26688
This PR adds a new key to neon.neon_lfc_stats —
'file_cache_chunk_size_pages'. It just returns the value of
BLOCKS_PER_CHUNK from the LFC implementation.
The new value should (eventually) allow changing the chunk size without
breaking any places that rely on LFC stats values measured in number of
chunks.
See neondatabase/cloud#25170 for more.
## Problem
It was reported as `gauge`, but it's actually a `counter`.
Also add `_total` suffix as that's the convention for counters.
The corresponding flux-fleet PR:
https://github.com/neondatabase/flux-fleet/pull/386
This will tell us how much time the compute has spent throttled if
pageserver/safekeeper cannot keep up with WAL generation.
Signed-off-by: Tristan Partin <tristan@neon.tech>
There are quite a few benefits to this approach:
- Reduce config duplication
- The two sql_exporter configs were super similar with just a few
differences
- Pull SQL queries into standalone files
- That means we could run a SQL formatter on the file in the future
- It also means access to syntax highlighting
- In the future, run different queries for different PG versions
- This is relevant because right now, we have queries that are failing
on PG 17 due to catalog updates
Signed-off-by: Tristan Partin <tristan@neon.tech>
