[receiver/sqlserver] Add access methods and buffer pool metrics (open-telemetry#49185)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description
Adds 7 new opt-in metrics to the sqlserverreceiver covering Access
Methods and Buffer Pool Extensions. These consolidate 14 separate
performance counters into attribute-based OTLP metrics, following the
receiver's existing consolidation pattern (e.g.,
sqlserver.page.operation with an attribute).

All new metrics reuse the existing sys.dm_os_performance_counters query
path — no new DMVs required.

<!-- Issue number (e.g. open-telemetry#1234) or full URL to issue, if applicable. -->
#### Link to tracking issue
Fixes open-telemetry#49182

<!--Describe what testing was performed and which tests were added.-->
#### Testing
- Unit tests for all 7 new metrics
- Integration tests against SQL Server instance
- metadata.yaml updated with metric definitions
- Documentation updated

<!--Describe the documentation added.-->
#### Documentation

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not check this box on behalf
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#### Authorship

- [x] I, a human, wrote this pull request description myself.

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---------

Signed-off-by: akshasri <akshaysrivastava@splunk.com>

Author: akshays-19

.chloggen/sqlserverreceiver-access-methods-and-buffer-pool.yaml

@@ -0,0 +1,36 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. receiver/filelog)
+component: receiver/sqlserver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Add access methods and buffer pool metrics
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [49182]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: |
+  Adds the following metrics, all disabled by default:
+    - `sqlserver.access.scan.rate`
+    - `sqlserver.extent.operation.rate`
+    - `sqlserver.ghost_record.skipped.rate`
+    - `sqlserver.page.allocation.rate`
+    - `sqlserver.page.compression.rate`
+    - `sqlserver.page.read_ahead.rate`
+    - `sqlserver.scan_point.revalidation.rate`
+    - `sqlserver.worktable.cache.hit_ratio`
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user]

receiver/sqlserverreceiver/documentation.md

@@ -220,6 +220,22 @@ metrics:
     enabled: true
 ```
 
+### sqlserver.access.scan.rate
+
+Rate of access method scans.
+
+This metric is only available when the receiver is configured to directly connect to SQL Server.
+
+| Unit | Metric Type | Value Type | Stability |
+| ---- | ----------- | ---------- | --------- |
+| {scan}/s | Gauge | Double | Development |
+
+#### Attributes
+
+| Name | Description | Values | Requirement Level | Semantic Convention |
+| ---- | ----------- | ------ | ----------------- | ------------------- |
+| sqlserver.access.scan.type | The type of access method scan being performed. | Str: ``free_space``, ``probe``, ``range`` | Required | - |
+
 ### sqlserver.attention.rate
 
 Number of SQL attentions (client cancellation interrupts) received per second.
@@ -371,6 +387,32 @@ Total number of deadlocks.
 | ---- | ----------- | ---------- | --------- |
 | “{deadlocks}/s” | Gauge | Double | Development |
 
+### sqlserver.extent.operation.rate
+
+Rate of extent operations.
+
+This metric is only available when the receiver is configured to directly connect to SQL Server.
+
+| Unit | Metric Type | Value Type | Stability |
+| ---- | ----------- | ---------- | --------- |
+| {extent}/s | Gauge | Double | Development |
+
+#### Attributes
+
+| Name | Description | Values | Requirement Level | Semantic Convention |
+| ---- | ----------- | ------ | ----------------- | ------------------- |
+| sqlserver.extent.operation.type | The type of extent allocation operation. | Str: ``allocated``, ``deallocated`` | Required | - |
+
+### sqlserver.ghost_record.skipped.rate
+
+Rate of ghosted records skipped during scans.
+
+This metric is only available when the receiver is configured to directly connect to SQL Server.
+
+| Unit | Metric Type | Value Type | Stability |
+| ---- | ----------- | ---------- | --------- |
+| {record}/s | Gauge | Double | Development |
+
 ### sqlserver.index.search.rate
 
 Total number of index searches.
@@ -550,6 +592,22 @@ This metric is only available when the receiver is configured to directly connec
 | wait.category | Category of the reason for a wait. | Any Str | Recommended | - |
 | wait.type | Type of the wait, view [WaitTypes documentation](https://learn.microsoft.com/en-us/sql/relational-databases/system-dynamic-management-views/sys-dm-os-wait-stats-transact-sql?view=sql-server-ver16#WaitTypes) for more information. | Any Str | Recommended | - |
 
+### sqlserver.page.allocation.rate
+
+Rate of page allocation operations.
+
+This metric is only available when the receiver is configured to directly connect to SQL Server.
+
+| Unit | Metric Type | Value Type | Stability |
+| ---- | ----------- | ---------- | --------- |
+| {page}/s | Gauge | Double | Development |
+
+#### Attributes
+
+| Name | Description | Values | Requirement Level | Semantic Convention |
+| ---- | ----------- | ------ | ----------------- | ------------------- |
+| sqlserver.page.allocation.type | The type of page allocation operation. | Str: ``allocated``, ``deallocated``, ``mixed`` | Required | - |
+
 ### sqlserver.page.buffer_cache.free_list.stalls.rate
 
 Number of free list stalls.
@@ -558,6 +616,22 @@ Number of free list stalls.
 | ---- | ----------- | ---------- | --------- |
 | “{stalls}/s” | Gauge | Int | Development |
 
+### sqlserver.page.compression.rate
+
+Rate of page compression operations.
+
+This metric is only available when the receiver is configured to directly connect to SQL Server.
+
+| Unit | Metric Type | Value Type | Stability |
+| ---- | ----------- | ---------- | --------- |
+| {page}/s | Gauge | Double | Development |
+
+#### Attributes
+
+| Name | Description | Values | Requirement Level | Semantic Convention |
+| ---- | ----------- | ------ | ----------------- | ------------------- |
+| sqlserver.page.compression.type | The type of page compression operation. | Str: ``attempted``, ``succeeded`` | Required | - |
+
 ### sqlserver.page.lookup.rate
 
 Total number of page lookups.
@@ -566,6 +640,16 @@ Total number of page lookups.
 | ---- | ----------- | ---------- | --------- |
 | “{lookups}/s” | Gauge | Double | Development |
 
+### sqlserver.page.read_ahead.rate
+
+Rate of pages read from disk by the read-ahead manager.
+
+This metric is only available when the receiver is configured to directly connect to SQL Server.
+
+| Unit | Metric Type | Value Type | Stability |
+| ---- | ----------- | ---------- | --------- |
+| {page}/s | Gauge | Double | Development |
+
 ### sqlserver.parameterization.rate
 
 Rate of auto-parameterization activity, broken down by result.
@@ -662,6 +746,16 @@ This metric is only available when the receiver is configured to directly connec
 | ---- | ----------- | ---------- | --------- |
 | {writes}/s | Gauge | Double | Development |
 
+### sqlserver.scan_point.revalidation.rate
+
+Rate at which scan points needed to be revalidated.
+
+This metric is only available when the receiver is configured to directly connect to SQL Server.
+
+| Unit | Metric Type | Value Type | Stability |
+| ---- | ----------- | ---------- | --------- |
+| {revalidate}/s | Gauge | Double | Development |
+
 ### sqlserver.table.count
 
 The number of tables.
@@ -693,6 +787,16 @@ Total number of mirror write transactions.
 | ---- | ----------- | ---------- | --------- |
 | “{transactions}/s” | Gauge | Double | Development |
 
+### sqlserver.worktable.cache.hit_ratio
+
+Fraction of worktables that did not require initialization because they were retrieved from the worktable cache.
+
+This metric is only available when the receiver is configured to directly connect to SQL Server.
+
+| Unit | Metric Type | Value Type | Stability |
+| ---- | ----------- | ---------- | --------- |
+| 1 | Gauge | Double | Development |
+
 ## Default Events
 
 The following events are emitted by default. Each of them can be disabled by applying the following configuration:

receiver/sqlserverreceiver/factory.go

@@ -259,7 +259,8 @@ func isPerfCounterQueryEnabled(metrics *metadata.MetricsConfig) bool {
 		return false
 	}
 
-	return metrics.SqlserverBatchRequestRate.Enabled ||
+	return metrics.SqlserverAccessScanRate.Enabled ||
+		metrics.SqlserverBatchRequestRate.Enabled ||
 		metrics.SqlserverBatchSQLCompilationRate.Enabled ||
 		metrics.SqlserverBatchSQLRecompilationRate.Enabled ||
 		metrics.SqlserverDatabaseBackupOrRestoreRate.Enabled ||
@@ -268,6 +269,8 @@ func isPerfCounterQueryEnabled(metrics *metadata.MetricsConfig) bool {
 		metrics.SqlserverDatabaseTempdbSpace.Enabled ||
 		metrics.SqlserverDatabaseTempdbVersionStoreSize.Enabled ||
 		metrics.SqlserverDeadlockRate.Enabled ||
+		metrics.SqlserverExtentOperationRate.Enabled ||
+		metrics.SqlserverGhostRecordSkippedRate.Enabled ||
 		metrics.SqlserverIndexSearchRate.Enabled ||
 		metrics.SqlserverLatchSuperlatchCount.Enabled ||
 		metrics.SqlserverLatchSuperlatchTransitionRate.Enabled ||
@@ -284,22 +287,27 @@ func isPerfCounterQueryEnabled(metrics *metadata.MetricsConfig) bool {
 		metrics.SqlserverMemoryGrantsPendingCount.Enabled ||
 		metrics.SqlserverMemoryPageCount.Enabled ||
 		metrics.SqlserverMemoryUsage.Enabled ||
+		metrics.SqlserverPageAllocationRate.Enabled ||
 		metrics.SqlserverPageBufferCacheFreeListStallsRate.Enabled ||
 		metrics.SqlserverPageBufferCacheHitRatio.Enabled ||
+		metrics.SqlserverPageCompressionRate.Enabled ||
 		metrics.SqlserverPageLookupRate.Enabled ||
+		metrics.SqlserverPageReadAheadRate.Enabled ||
 		metrics.SqlserverProcessesBlocked.Enabled ||
 		metrics.SqlserverReplicaDataRate.Enabled ||
 		metrics.SqlserverResourcePoolDiskThrottledReadRate.Enabled ||
 		metrics.SqlserverResourcePoolDiskOperations.Enabled ||
 		metrics.SqlserverResourcePoolDiskThrottledWriteRate.Enabled ||
+		metrics.SqlserverScanPointRevalidationRate.Enabled ||
 		metrics.SqlserverAttentionRate.Enabled ||
 		metrics.SqlserverParameterizationRate.Enabled ||
 		metrics.SqlserverPlanExecutionRate.Enabled ||
 		metrics.SqlserverRecompilationRatio.Enabled ||
 		metrics.SqlserverTableCount.Enabled ||
 		metrics.SqlserverTransactionDelay.Enabled ||
 		metrics.SqlserverTransactionMirrorWriteRate.Enabled ||
-		metrics.SqlserverUserConnectionCount.Enabled
+		metrics.SqlserverUserConnectionCount.Enabled ||
+		metrics.SqlserverWorktableCacheHitRatio.Enabled
 }
 
 func isWaitStatsQueryEnabled(metrics *metadata.MetricsConfig) bool {

receiver/sqlserverreceiver/factory_test.go

@@ -262,7 +262,7 @@ func TestSetupQueries(t *testing.T) {
 
 	metricsMetadata, ok := metadata["metrics"].(map[string]any)
 	require.True(t, ok)
-	require.Len(t, metricsMetadata, 62, "Every time metrics are added or removed, the function `setupQueries` must "+
+	require.Len(t, metricsMetadata, 70, "Every time metrics are added or removed, the function `setupQueries` must "+
 		"be modified to properly account for the change. Please update `setupQueries` and then, "+
 		"and only then, update the expected metric count here.")
 }