PG-1383 Record fait PG version in telemetry file

percona_pg_telemetry.c

@@ -850,6 +850,60 @@ write_database_info(PTDatabaseInfo *dbinfo, List *extlist)
 	return true;
 }
 
+
+/*
+* Function to write the pg_version to the telemetry file.
+*/
+static void
+write_pg_version()
+{
+	int			spi_result;
+	char	   *query = "select setting from pg_settings where name='server_version'";
+	char		buf[1024] = {0};
+	size_t		buf_size = sizeof(buf);
+	FILE	   *fp;
+
+	/* Open file in append mode. */
+	fp = open_telemetry_file(ptss->dbtemp_filepath, "a+");
+
+	SetCurrentStatementStartTimestamp();
+	StartTransactionCommand();
+
+	/* Initialize SPI */
+	spi_result = SPI_connect();
+	if (spi_result != SPI_OK_CONNECT)
+	{
+		ereport(ERROR, (errmsg("Failed to connect to SPI")));
+	}
+
+	PushActiveSnapshot(GetTransactionSnapshot());
+
+	/* Execute the query */
+	spi_result = SPI_execute(query, true, 0);
+	if (spi_result != SPI_OK_SELECT)
+	{
+		SPI_finish();
+		ereport(ERROR, (errmsg("Failed to execute query")));
+	}
+
+	if (SPI_processed > 0)
+	{
+		char	   *version = SPI_getvalue(SPI_tuptable->vals[0], SPI_tuptable->tupdesc, 1);
+
+		construct_json_block(buf, buf_size, "pillar_version", version, PT_JSON_KEY_VALUE, &ptss->json_file_indent);
+		write_telemetry_file(fp, buf);
+	}
+
+	/* Close the file */
+	fclose(fp);
+
+	/* Disconnect from SPI */
+	SPI_finish();
+
+	PopActiveSnapshot();
+	CommitTransactionCommand();
+}
+
 /*
  * Main function for the background launcher process
  */
@@ -949,10 +1003,6 @@ percona_pg_telemetry_main(Datum main_arg)
 			construct_json_block(buf, buf_size, "db_instance_id", str, PT_JSON_KEY_VALUE, &ptss->json_file_indent);
 			write_telemetry_file(fp, buf);
 
-			/* Construct and initiate the active extensions array block. */
-			construct_json_block(buf, buf_size, "pillar_version", PG_VERSION, PT_JSON_KEY_VALUE, &ptss->json_file_indent);
-			write_telemetry_file(fp, buf);
-
 			/* Construct and initiate the active extensions array block. */
 			pg_snprintf(str, sizeof(str), "%ld", server_uptime());
 			construct_json_block(buf, buf_size, "uptime", str, PT_JSON_KEY_VALUE, &ptss->json_file_indent);
@@ -1088,7 +1138,10 @@ percona_pg_telemetry_worker(Datum main_arg)
 
 	/* Get the settings */
 	if (ptss->first_db_entry)
+	{
+		write_pg_version();
 		write_pg_settings();
+	}
 
 	extlist = get_extensions_list(&ptss->dbinfo, tmpcxt);