Add parallel operations metrics to oracledb receiver (open-telemetry#39215)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description

This PR adds the following metrics to the `oracledb` receiver:
- 'DDL statements parallelized'
- 'DML statements parallelized'
- 'Parallel operations not downgraded'
- 'Parallel operations downgraded to serial'
- 'Parallel operations downgraded (1-25%)'
- 'Parallel operations downgraded (25-50%)'
- 'Parallel operations downgraded (50-75%)'
- 'Parallel operations downgraded (75-99%)'

They are all disabled by default.

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

<!--Describe what testing was performed and which tests were added.-->
#### Testing
Manual testing.
<!--Describe the documentation added.-->
#### Documentation
Automatically generated by `mdatagen` for each metric.
<!--Please delete paragraphs that you did not use before submitting.-->

Author: ccressent

.chloggen/oracledb-parallel-ops-metrics.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. filelogreceiver)
+component: oracledbreceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Add support for parallel operations metrics
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [39215]
+
+# (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: |
+  The following metrics are now available, all disabled by default:
+  - 'DDL statements parallelized'
+  - 'DML statements parallelized'
+  - 'Parallel operations not downgraded'
+  - 'Parallel operations downgraded to serial'
+  - 'Parallel operations downgraded (1-25%)'
+  - 'Parallel operations downgraded (25-50%)'
+  - 'Parallel operations downgraded (50-75%)'
+  - 'Parallel operations downgraded (75-99%)'
+
+# 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/oracledbreceiver/documentation.md

@@ -257,6 +257,70 @@ Number of times a current block was requested from the buffer cache.
 | ---- | ----------- | ---------- | ----------------------- | --------- |
 | {gets} | Sum | Int | Cumulative | true |
 
+### oracledb.ddl_statements_parallelized
+
+Number of DDL statements that were executed in parallel
+
+| Unit | Metric Type | Value Type | Aggregation Temporality | Monotonic |
+| ---- | ----------- | ---------- | ----------------------- | --------- |
+| {statements} | Sum | Int | Cumulative | true |
+
+### oracledb.dml_statements_parallelized
+
+Number of DML statements that were executed in parallel
+
+| Unit | Metric Type | Value Type | Aggregation Temporality | Monotonic |
+| ---- | ----------- | ---------- | ----------------------- | --------- |
+| {statements} | Sum | Int | Cumulative | true |
+
+### oracledb.parallel_operations_downgraded_1_to_25_pct
+
+Number of times parallel execution was requested and the degree of parallelism was reduced down to 1-25% because of insufficient parallel execution servers
+
+| Unit | Metric Type | Value Type | Aggregation Temporality | Monotonic |
+| ---- | ----------- | ---------- | ----------------------- | --------- |
+| {executions} | Sum | Int | Cumulative | true |
+
+### oracledb.parallel_operations_downgraded_25_to_50_pct
+
+Number of times parallel execution was requested and the degree of parallelism was reduced down to 25-50% because of insufficient parallel execution servers
+
+| Unit | Metric Type | Value Type | Aggregation Temporality | Monotonic |
+| ---- | ----------- | ---------- | ----------------------- | --------- |
+| {executions} | Sum | Int | Cumulative | true |
+
+### oracledb.parallel_operations_downgraded_50_to_75_pct
+
+Number of times parallel execution was requested and the degree of parallelism was reduced down to 50-75% because of insufficient parallel execution servers
+
+| Unit | Metric Type | Value Type | Aggregation Temporality | Monotonic |
+| ---- | ----------- | ---------- | ----------------------- | --------- |
+| {executions} | Sum | Int | Cumulative | true |
+
+### oracledb.parallel_operations_downgraded_75_to_99_pct
+
+Number of times parallel execution was requested and the degree of parallelism was reduced down to 75-99% because of insufficient parallel execution servers
+
+| Unit | Metric Type | Value Type | Aggregation Temporality | Monotonic |
+| ---- | ----------- | ---------- | ----------------------- | --------- |
+| {executions} | Sum | Int | Cumulative | true |
+
+### oracledb.parallel_operations_downgraded_to_serial
+
+Number of times parallel execution was requested but execution was serial because of insufficient parallel execution servers
+
+| Unit | Metric Type | Value Type | Aggregation Temporality | Monotonic |
+| ---- | ----------- | ---------- | ----------------------- | --------- |
+| {executions} | Sum | Int | Cumulative | true |
+
+### oracledb.parallel_operations_not_downgraded
+
+Number of times parallel execution was executed at the requested degree of parallelism
+
+| Unit | Metric Type | Value Type | Aggregation Temporality | Monotonic |
+| ---- | ----------- | ---------- | ----------------------- | --------- |
+| {executions} | Sum | Int | Cumulative | true |
+
 ### oracledb.physical_read_io_requests
 
 Number of read requests for application activity
@@ -297,6 +361,14 @@ Number of writes directly to disk, bypassing the buffer cache
 | ---- | ----------- | ---------- | ----------------------- | --------- |
 | {writes} | Sum | Int | Cumulative | true |
 
+### oracledb.queries_parallelized
+
+Number of SELECT statements executed in parallel
+
+| Unit | Metric Type | Value Type | Aggregation Temporality | Monotonic |
+| ---- | ----------- | ---------- | ----------------------- | --------- |
+| {queries} | Sum | Int | Cumulative | true |
+
 ## Resource Attributes
 
 | Name | Description | Values | Enabled |