[BUG] Lite - CalculateDelta fix not implemented everywhere

[dphugo]

Component

Lite

Performance Monitor Version

2.3.0

SQL Server Version

SQL Server 2022 (RTM-CU16)

Windows Version

Windows 11 23H2

Describe the Bug

1. CalculateDelta fix not implemented from all references.

Thanks for the fix of #544 with #546
Unfortunately only Perfom reference to CalculateDelta was fixed, but all other references to CalculateDelta needs to be evaluated whether it is affected by #544.

2. Server Tab -> File I/O -> File I/O Throughput : Graph series labels, shows as "unknown".

This might be by design, but the labels on this graph shows the database name and then "unknown" not sure what this should be? Maybe a bug?

Steps to Reproduce

Some examples, but could be more
Server Tab -> Blocking -> Trends
Server Tab -> File I/O -> File I/O Throughput

Expected Behavior

1. Graphs should only plot deltas whether missed collection or on startup.
2. Server Tab -> File I/O -> File I/O Throughput. Graph series labels, not sure what "Unknown" should be, but maybe there is missing label

Actual Behavior

1. Graphs plot aggregate over missed collection or on startup time periods since last collection.
2. Server Tab -> File I/O -> File I/O Throughput. Graph series labels, not sure what "Unknown" should be, but maybe there is missing label

Error Messages / Log Output

NA

Screenshots

Additional Context

Lite only tested.

[erikdarlingdata]

Thanks for the report. Two things going on here:

1. "Unknown" file labels — fixed

The File I/O chart labels were showing "Unknown" because of a NULL fallback in the C# reader code. When sys.master_files doesn't match via the LEFT JOIN, the file name comes back NULL and was being replaced with the string "Unknown".

Fixed in PR #636 — now shows DB_{database_id}.File_{file_id} instead of Unknown so the labels are at least identifiable.

Question for you: Can you help us understand why sys.master_files would return NULL for some files? Here's the on-prem query we use:

SELECT
    database_name = ISNULL(d.name, N'Unknown'),
    file_name = mf.name,
    file_type = mf.type_desc,
    physical_name = mf.physical_name,
    ...
FROM sys.dm_io_virtual_file_stats(NULL, NULL) AS vfs
LEFT JOIN sys.master_files AS mf
  ON  mf.database_id = vfs.database_id
  AND mf.file_id = vfs.file_id
LEFT JOIN sys.databases AS d
  ON  d.database_id = vfs.database_id
WHERE (vfs.database_id > 4 OR vfs.database_id = 2)
AND   vfs.database_id < 32761
AND   vfs.database_id <> ISNULL(DB_ID(N'PerformanceMonitor'), 0)
OPTION(RECOMPILE);

Could you run that query on your server and check which rows have NULL mf.name? Curious what database_id and file_id values are coming back from dm_io_virtual_file_stats without a match in sys.master_files. It might be FILESTREAM containers, in-memory OLTP filegroups, or something else we should handle differently.

2. CalculateDelta gap detection — investigating

You're right that the maxGapSeconds fix from #546 was only applied to the perfmon collector. The same gap detection needs to be added to all collectors that use CalculateDelta:

• File I/O (reads, writes, stalls)
• Wait stats
• Query stats
• Procedure stats
• Memory grants

All of these pass baselineOnly: true but none of them pass collectionTime and maxGapSeconds, so they'll produce inflated deltas after an app restart when the cached baseline is stale. Working on a fix for this.

[dphugo]

Thanks for the quick response, @erikdarlingdata.
On issue 1: I've narrowed it down that I don't have VIEW ANY DEFINITION role on this specific server.

SELECT
    IS_SRVROLEMEMBER('sysadmin') AS is_sysadmin,
    HAS_PERMS_BY_NAME(NULL, NULL, 'VIEW ANY DATABASE') AS can_view_any_database,
    HAS_PERMS_BY_NAME(NULL, NULL, 'VIEW SERVER STATE') AS can_view_server_state,
    HAS_PERMS_BY_NAME(NULL, NULL, 'VIEW ANY DEFINITION') AS can_view_ANY_DEFINITION;

The sys.dm_io_virtual_file_stats(NULL, NULL) and sys.databases do return rows, but sys.master_files does not return any rows.
On servers where I do have VIEW ANY DEFINITION role, sys.master_files does return rows.

Additionally this might explain why some data grids in FinOps do not populate?

• Utilization -> Database sizes - Allocated vs Used

• Storage Growth

• Database Sizes

I will request VIEW ANY DEFINITION role on this specific server. 👍

[erikdarlingdata]

@dphugo Ah! Very good! I will still leave in fixes for the unknown thing, since I assume at some point it'll come up for someone else.