feat(bigquery): make maximum rows returned from queries configurable

docs/en/resources/sources/bigquery.md

@@ -124,6 +124,7 @@ sources:
     #   - "my_dataset_1"
     #   - "other_project.my_dataset_2"
     # impersonateServiceAccount: "[email protected]" # Optional: Service account to impersonate
+    # maxResultRows: 50 # Optional: Limits the number of rows returned by queries. Defaults to 50.
 ```
 
 Initialize a BigQuery source that uses the client's access token:
@@ -140,6 +141,7 @@ sources:
     #   - "my_dataset_1"
     #   - "other_project.my_dataset_2"
     # impersonateServiceAccount: "[email protected]" # Optional: Service account to impersonate
+    # maxResultRows: 50 # Optional: Limits the number of rows returned by queries. Defaults to 50.
 ```
 
 ## Reference
@@ -153,3 +155,4 @@ sources:
 | allowedDatasets           | []string |    false     | An optional list of dataset IDs that tools using this source are allowed to access. If provided, any tool operation attempting to access a dataset not in this list will be rejected. To enforce this, two types of operations are also disallowed: 1) Dataset-level operations (e.g., `CREATE SCHEMA`), and 2) operations where table access cannot be statically analyzed (e.g., `EXECUTE IMMEDIATE`, `CREATE PROCEDURE`). If a single dataset is provided, it will be treated as the default for prebuilt tools. |
 | useClientOAuth            |   bool   |    false     | If true, forwards the client's OAuth access token from the "Authorization" header to downstream queries. **Note:** This cannot be used with `writeMode: protected`.                                                                                                                                                                                                                                                                                                                                                |
 | impersonateServiceAccount |  string  |    false     | Service account email to impersonate when making BigQuery and Dataplex API calls. The authenticated principal must have the `roles/iam.serviceAccountTokenCreator` role on the target service account. [Learn More](https://cloud.google.com/iam/docs/service-account-impersonation)                                                                                                                                                                                                                                |
+| maxResultRows             |   int    |    false     | The maximum number of rows to return from a query. Defaults to 50. |

internal/prebuiltconfigs/tools/bigquery.yaml

@@ -18,6 +18,7 @@ sources:
     project: ${BIGQUERY_PROJECT}
     location: ${BIGQUERY_LOCATION:}
     useClientOAuth: ${BIGQUERY_USE_CLIENT_OAUTH:false}
+    maxResultRows: ${BIGQUERY_MAX_RESULT_ROWS:50}
 
 tools:
   analyze_contribution:

internal/sources/bigquery/bigquery.go

@@ -85,6 +85,7 @@
 	AllowedDatasets           []string `yaml:"allowedDatasets"`
 	UseClientOAuth            bool     `yaml:"useClientOAuth"`
 	ImpersonateServiceAccount string   `yaml:"impersonateServiceAccount"`
+	MaxResultRows             int      `yaml:"maxResultRows"`
 }
 
 func (r Config) SourceConfigKind() string {
@@ -119,7 +120,7 @@
 		Client:             client,
 		RestService:        restService,
 		TokenSource:        tokenSource,
-		MaxQueryResultRows: 50,
+		MaxQueryResultRows: r.MaxResultRows,
 		ClientCreator:      clientCreator,
 	}
 
@@ -530,6 +531,9 @@
 
 	var out []any
 	for {
+		if s.MaxQueryResultRows > 0 && len(out) >= s.MaxQueryResultRows {
+			break
+		}
 		var val []bigqueryapi.Value
 		err = it.Next(&val)
 		if err == iterator.Done {