fix(influxdb3): document exec-mem-pool-bytes usage for data persistence (#6394)

* fix(influxdb3): document exec-mem-pool-bytes usage for data persistence

Updates documentation to reflect that exec-mem-pool-bytes is used for both
query processing and parquet persistence operations, not just queries.

Based on source code analysis showing the memory pool is used by:
- Query executor for processing queries
- Persister for converting WAL data to Parquet format

Changes:
- Updated config description to include "data operations"
- Added memory usage info to durability docs for Parquet storage
- Added troubleshooting section for memory-related write performance
- Fixed capitalization of "object store" throughout

Addresses DAR #499

Source analysis: influxdb3/src/commands/serve.rs:772-798
Shows separate executors for queries and write path operations,
both using memory pools for data processing.

* fix(influxdb3): broken links to no-sync

Author: jstirnaman

content/shared/influxdb3-cli/config-options.md

@@ -1088,7 +1088,9 @@ Defines the address on which InfluxDB serves HTTP API requests.
 
 #### exec-mem-pool-bytes
 
-Specifies the size of memory pool used during query execution.
+Specifies the size of the memory pool used for query processing and data operations.
+This memory pool is used when {{% product-name %}} processes queries and performs
+internal data management tasks.
 Can be given as absolute value in bytes or as a percentage of the total available memory--for
 example: `8000000000` or `10%`.
 

content/shared/influxdb3-internals-reference/durability.md

@@ -19,14 +19,14 @@ As written data moves through {{% product-name %}}, it follows a structured path
 
 - **Process**: InfluxDB validates incoming data before accepting it into the system.
 - **Impact**: Prevents malformed or unsupported data from entering the database.
-- **Details**: The database validates incoming data and stores it in the write buffer (in memory). If [`no_sync=true`](#no-sync-write-option), the server sends a response to acknowledge the write.
+- **Details**: The database validates incoming data and stores it in the write buffer (in memory). If `no_sync=true`, the server sends a response to acknowledge the write [without waiting for persistence](/influxdb3/version/reference/cli/influxdb3/write/#write-line-protocol-and-immediately-return-a-response).
 
 ### Write-ahead log (WAL) persistence
 
 - **Process**: The database flushes the write buffer to the WAL every second (default).
 - **Impact**: Ensures durability by persisting data to object storage.
 - **Tradeoff**: More frequent flushing improves durability but increases I/O overhead.
-- **Details**: Every second (default), the database flushes the write buffer to the Write-Ahead Log (WAL) for persistence in the Object store. If [`no_sync=false`](#no-sync-write-option) (default), the server sends a response to acknowledge the write.
+- **Details**: Every second (default), the database flushes the write buffer to the Write-Ahead Log (WAL) for persistence in the object store. If `no_sync=false` (default), the server sends a response to acknowledge the write.
 
 ### Query availability
 
@@ -40,7 +40,8 @@ As written data moves through {{% product-name %}}, it follows a structured path
 - **Process**: Every ten minutes (default), data is persisted to Parquet files in object storage.
 - **Impact**: Provides durable, long-term storage.
 - **Tradeoff**: More frequent persistence reduces reliance on the WAL but increases I/O costs.
-- **Details**: Every ten minutes (default), the {{% product-name %}} persists the oldest data from the queryable buffer to the Object store in Parquet format, and keeps the remaining data (the most recent 5 minutes) in memory.
+- **Memory usage**: The persistence process uses memory from the configured memory pool ([`exec-mem-pool-bytes`](/influxdb3/version/reference/config-options/#exec-mem-pool-bytes)) when converting data to Parquet format. For write-heavy workloads, ensure adequate memory is allocated.
+- **Details**: Every ten minutes (default), {{% product-name %}} persists the oldest data from the queryable buffer to the object store in Parquet format, and keeps the remaining data (the most recent 5 minutes) in memory.
 
 ### In-memory cache
 

content/shared/influxdb3-write-guides/troubleshoot.md

@@ -6,6 +6,7 @@ Learn how to avoid unexpected results and recover from errors when writing to
   - [Review HTTP status codes](#review-http-status-codes)
 - [Troubleshoot failures](#troubleshoot-failures)
 - [Troubleshoot rejected points](#troubleshoot-rejected-points)
+{{% show-in "core,enterprise" %}}- [Troubleshoot write performance issues](#troubleshoot-write-performance-issues){{% /show-in %}}
 
 ## Handle write responses
 
@@ -65,3 +66,43 @@ InfluxDB rejects points that don't match the schema of existing data.
 Check for [field data type](/influxdb3/version/reference/syntax/line-protocol/#data-types-and-format)
 differences between the rejected data point and points within the same
 database--for example, did you attempt to write `string` data to an `int` field?
+
+{{% show-in "core,enterprise" %}}
+
+## Troubleshoot write performance issues
+
+If you experience slow write performance or timeouts during high-volume ingestion,
+consider the following:
+
+### Memory configuration
+
+{{% product-name %}} uses memory for both query processing and internal data operations,
+including converting data to Parquet format during persistence.
+For write-heavy workloads, insufficient memory allocation can cause performance issues.
+
+**Symptoms of memory-related write issues:**
+- Slow write performance during data persistence (typically every 10 minutes)
+- Increased response times during high-volume ingestion
+- Memory-related errors in server logs
+
+**Solutions:**
+- Increase the [`exec-mem-pool-bytes`](/influxdb3/version/reference/config-options/#exec-mem-pool-bytes)
+  configuration to allocate more memory for data operations.
+  For write-heavy workloads, consider setting this to 30-40% of available memory.
+- Monitor memory usage during peak write periods to identify bottlenecks.
+- Adjust the [`gen1-duration`](/influxdb3/version/reference/config-options/#gen1-duration)
+  to control how frequently data is persisted to Parquet format.
+
+### Example configuration for write-heavy workloads
+
+```bash { placeholders="PERCENTAGE" }
+influxdb3 serve \
+  --exec-mem-pool-bytes PERCENTAGE \
+  --gen1-duration 15m \
+  # ... other options
+```
+
+Replace {{% code-placeholder-key %}}`PERCENTAGE`{{% /code-placeholder-key %}} with the percentage
+of available memory to allocate (for example, `35%` for write-heavy workloads).
+
+{{% /show-in %}}