Document BigQuery RPC settings

docs/src/main/sphinx/connector/bigquery.md

@@ -177,6 +177,59 @@ a few caveats:
   - Enable using Apache Arrow serialization when reading data from BigQuery.
     Please read this [section](bigquery-arrow-serialization-support) before using this feature.
   - `true`
+* - `bigquery.channel-pool.initial-size`
+  - The initial size of the connection pool, also known as a channel pool,
+    used for gRPC communication.
+  - `1`
+* - `bigquery.channel-pool.min-size`
+  - The absolute minimum size of the connection pool, also known as a channel
+    pool, used for gRPC communication.
+  - `1`
+* - `bigquery.channel-pool.max-size`
+  - The absolute maximum size of the connection pool, also known as a channel
+    pool, used for gRPC communication.
+  - `1`
+* - `bigquery.channel-pool.min-rpc-per-channel`
+  - Threshold to start scaling down the channel pool.
+    When the average of the maximum number of outstanding RPCs in a single
+    minute drop below this threshold, channels will be removed from the pool.
+  - `0`
+* - `bigquery.channel-pool.max-rpc-per-channel`
+  - Threshold to start scaling up the channel pool.
+    When the average of the maximum number of outstanding RPCs in a single
+    minute surpass this threshold, channels will be added to the pool.
+  - `2147483647`
+* - `bigquery.rpc-retries`
+  - The maximum number of retry attempts to perform for the RPC calls.
+    If this value is set to `0`, the logic will instead use the
+    `bigquery.rpc-timeout` configuration value to determine retries. 
+    In the event that both the `bigquery.rpc-retries` and
+    `bigquery.rpc-timeout` values are both `0`, the logic will not retry.
+    If this value is positive, and the number of attempts exceeds
+    `bigquery.rpc-retries` limit, the logic will give up retrying even if
+    the total retry time is still lower than `bigquery.rpc-timeout`.
+  - `0`
+* - `bigquery.rpc-timeout`
+  - Timeout [duration](prop-type-duration) on when the retries for the
+    RPC call should be given up completely. The higher the timeout, the
+    more retries can be attempted. If this value is `0s`, then
+    the logic will instead use `bigquery.rpc-retries` to determine retries.
+    In the event that `bigquery.rpc-retries` and `bigquery.rpc-timeout`
+    values are both `0`, the logic will not retry. 
+    If this value is positive, and the retry duration has reached the timeout
+    value, the logic will give up retrying even the number of attempts is
+    lower than the `bigquery.rpc-retries` value.
+  - `0s`
+* - `bigquery.rpc-retry-delay`
+  - The delay [duration](prop-type-duration) before the first retry attempt
+    for RPC calls.
+  - `0s`
+* - `bigquery.rpc-retry-delay-multiplier`
+  - Controls the change in delay before the next retry.
+    The retry delay of the previous call is multiplied by the
+    `bigquery.rpc-retry-delay-multiplier` to calculate the retry delay
+    for the next RPC call.
+  - `1.0`
 * - `bigquery.rpc-proxy.enabled`
   - Use a proxy for communication with BigQuery.
   - `false`