Do transaction checks before SPI call

tsl/src/continuous_aggs/refresh.c

@@ -768,13 +768,24 @@ continuous_agg_refresh_internal(const ContinuousAgg *cagg,
 	bool nonatomic = ts_process_utility_is_context_nonatomic();
 
 	/* Reset the saved ProcessUtilityContext value promptly before
-	 * calling PreventCommandIfReadOnly so the potential unsupported
-	 * (atomic) value won't linger there in case of ereport exit.
+	 * calling Prevent* checks so the potential unsupported (atomic)
+	 * value won't linger there in case of ereport exit.
 	 */
 	ts_process_utility_context_reset();
 
+	PreventCommandIfReadOnly(REFRESH_FUNCTION_NAME);
+
+	/* Prevent running refresh if we're in a transaction block since a refresh
+	 * can run two transactions and might take a long time to release locks if
+	 * there's a lot to materialize. Strictly, it is optional to prohibit
+	 * transaction blocks since there will be only one transaction if the
+	 * invalidation threshold needs no update. However, materialization might
+	 * still take a long time and it is probably best for consistency to always
+	 * prevent transaction blocks.  */
+	PreventInTransactionBlock(nonatomic, REFRESH_FUNCTION_NAME);
+
 	/* Connect to SPI manager due to the underlying SPI calls */
-	int rc = SPI_connect_ext(nonatomic ? SPI_OPT_NONATOMIC : 0);
+	int rc = SPI_connect_ext(SPI_OPT_NONATOMIC);
 	if (rc != SPI_OK_CONNECT)
 		elog(ERROR, "SPI_connect failed: %s", SPI_result_code_string(rc));
 
@@ -788,17 +799,6 @@ continuous_agg_refresh_internal(const ContinuousAgg *cagg,
 					   get_relkind_objtype(get_rel_relkind(cagg->relid)),
 					   get_rel_name(cagg->relid));
 
-	PreventCommandIfReadOnly(REFRESH_FUNCTION_NAME);
-
-	/* Prevent running refresh if we're in a transaction block since a refresh
-	 * can run two transactions and might take a long time to release locks if
-	 * there's a lot to materialize. Strictly, it is optional to prohibit
-	 * transaction blocks since there will be only one transaction if the
-	 * invalidation threshold needs no update. However, materialization might
-	 * still take a long time and it is probably best for consistency to always
-	 * prevent transaction blocks.  */
-	PreventInTransactionBlock(nonatomic, REFRESH_FUNCTION_NAME);
-
 	/* No bucketing when open ended */
 	if (!(start_isnull && end_isnull))
 	{