Fix ParameterStatus capitalization for DateStyle, TimeZone, and IntervalStyle

These parameters use capitalized names in PostgreSQL for historical reasons.
ProxySQL now sends them using canonical capitalization to ensure client compatibility.

include/proxysql_structs.h

@@ -1817,10 +1817,10 @@ extern const pgsql_variable_validator pgsql_variable_validator_client_encoding;
 
 pgsql_variable_st pgsql_tracked_variables[]{
 	{ PGSQL_CLIENT_ENCODING,       SETTING_VARIABLE,	"client_encoding", "client_encoding", "UTF8", (PGTRACKED_VAR_OPT_QUOTE | PGTRACKED_VAR_OPT_PARAM_STATUS), &pgsql_variable_validator_client_encoding, { "names", nullptr } },
-	{ PGSQL_DATESTYLE,			   SETTING_VARIABLE,	"datestyle", "datestyle", "ISO, MDY" , (PGTRACKED_VAR_OPT_QUOTE | PGTRACKED_VAR_OPT_PARAM_STATUS), &pgsql_variable_validator_datestyle, nullptr },
-	{ PGSQL_INTERVALSTYLE,		   SETTING_VARIABLE,	"intervalstyle", "intervalstyle", "postgres" , (PGTRACKED_VAR_OPT_QUOTE | PGTRACKED_VAR_OPT_PARAM_STATUS), &pgsql_variable_validator_intervalstyle, nullptr },
+	{ PGSQL_DATESTYLE,			   SETTING_VARIABLE,	"DateStyle", "datestyle", "ISO, MDY" , (PGTRACKED_VAR_OPT_QUOTE | PGTRACKED_VAR_OPT_PARAM_STATUS), &pgsql_variable_validator_datestyle, nullptr },
+	{ PGSQL_INTERVALSTYLE,		   SETTING_VARIABLE,	"IntervalStyle", "intervalstyle", "postgres" , (PGTRACKED_VAR_OPT_QUOTE | PGTRACKED_VAR_OPT_PARAM_STATUS), &pgsql_variable_validator_intervalstyle, nullptr },
 	{ PGSQL_STANDARD_CONFORMING_STRINGS, SETTING_VARIABLE, "standard_conforming_strings", "standard_conforming_strings", "on", (PGTRACKED_VAR_OPT_PARAM_STATUS), &pgsql_variable_validator_bool, nullptr },
-	{ PGSQL_TIMEZONE,			   SETTING_VARIABLE,	"timezone", "timezone", "GMT" , (PGTRACKED_VAR_OPT_QUOTE | PGTRACKED_VAR_OPT_PARAM_STATUS), nullptr, { "TIME ZONE", nullptr } },
+	{ PGSQL_TIMEZONE,			   SETTING_VARIABLE,	"TimeZone", "timezone", "GMT" , (PGTRACKED_VAR_OPT_QUOTE | PGTRACKED_VAR_OPT_PARAM_STATUS), nullptr, { "TIME ZONE", nullptr } },
 	{ PGSQL_NAME_LAST_LOW_WM,      session_status___NONE, "placeholder", "placeholder", "0" , 0, nullptr, nullptr },  // this is just a placeholder to separate the previous index from the next block
 	{ PGSQL_ALLOW_IN_PLACE_TABLESPACES,	   SETTING_VARIABLE,	"allow_in_place_tablespaces", "allow_in_place_tablespaces", "off", (0), &pgsql_variable_validator_bool, nullptr },
 	{ PGSQL_BYTEA_OUTPUT,		   SETTING_VARIABLE,	"bytea_output", "bytea_output", "hex", (PGTRACKED_VAR_OPT_QUOTE), &pgsql_variable_validator_bytea_output,  nullptr },

lib/PgSQL_Connection.cpp

@@ -20,11 +20,11 @@ extern char * binary_sha1;
 #include "proxysql_find_charset.h"
 
 void PgSQL_Variable::fill_server_internal_session(json &j, int conn_num, int idx) {
-	j[conn_num]["conn"][pgsql_tracked_variables[idx].internal_variable_name] = std::string(value?value:"");
+	j[conn_num]["conn"][pgsql_tracked_variables[idx].set_variable_name] = std::string(value?value:"");
 }
 
 void PgSQL_Variable::fill_client_internal_session(json &j, int idx) {
-	j["conn"][pgsql_tracked_variables[idx].internal_variable_name] = value?value:"";
+	j["conn"][pgsql_tracked_variables[idx].set_variable_name] = value?value:"";
 }
 
 PgSQL_Connection_userinfo::PgSQL_Connection_userinfo() {

lib/PgSQL_Protocol.cpp

@@ -1096,8 +1096,9 @@ EXECUTION_STATE PgSQL_Protocol::process_handshake_response_packet(unsigned char*
 			for (int i = 0; i < PGSQL_NAME_LAST_HIGH_WM; i++) {
 				if (i == PGSQL_NAME_LAST_LOW_WM)
 					continue;
-				if (strncmp(param_key.c_str(), pgsql_tracked_variables[i].set_variable_name, 
-					strlen(pgsql_tracked_variables[i].set_variable_name)) == 0) {
+				// using internal_variable_name because it follows the lowercase naming convention
+				if (strncmp(param_key.c_str(), pgsql_tracked_variables[i].internal_variable_name,
+					strlen(pgsql_tracked_variables[i].internal_variable_name)) == 0) {
 					idx = i;
 					break;
 				}
@@ -1248,7 +1249,7 @@ void PgSQL_Protocol::welcome_client() {
 
 		const char* val = pgsql_variables.client_get_value(sess, idx);
 		if (val)
-			pgpkt.write_ParameterStatus(pgsql_tracked_variables[idx].internal_variable_name, val);
+			pgpkt.write_ParameterStatus(pgsql_tracked_variables[idx].set_variable_name, val);
 	}
 
 	if (pgsql_thread___server_version)

lib/PgSQL_Variables.cpp

@@ -36,10 +36,8 @@ PgSQL_Variables::PgSQL_Variables() {
 			assert(strcmp(pgsql_tracked_variables[i].set_variable_name, pgsql_tracked_variables[i - 1].set_variable_name) > 0);
 		}
 
-		// we initialized all the internal_variable_name if set to NULL
-		if (pgsql_tracked_variables[i].internal_variable_name == NULL) {
-			pgsql_tracked_variables[i].internal_variable_name = pgsql_tracked_variables[i].set_variable_name;
-		}
+		// internal_variable_name should not be null
+		assert(pgsql_tracked_variables[i].internal_variable_name != NULL);
 
 		PgSQL_Variables::verifiers[i] = verify_server_variable;
 		PgSQL_Variables::updaters[i] = update_server_variable;