fix: Remove unused legacy mcp-mysql_* variables

These variables were deprecated in favor of profile-based routing but
were never removed from the code. They existed in the struct definition,
getters, and setters but were not consumed anywhere - Query_Tool_Handler
uses target_auth_map via mcp_auth_profiles and mcp_target_profiles.

Removed:
- mcp-mysql_hosts, mcp-mysql_ports, mcp-mysql_user, mcp-mysql_password,
  mcp-mysql_schema from MCP_Thread.h struct
- Variable names from mcp_thread_variables_names array
- Initialization, cleanup, getters, and setters in MCP_Thread.cpp
- Documentation in doc/MCP/VARIABLES.md

doc/MCP/VARIABLES.md

@@ -151,62 +151,6 @@ Backend credentials are defined in MCP tables, not in client requests:
 
 The in-memory target/auth map is loaded by `MCP_Threads_Handler` from runtime tables and used by the query executor connection pools.
 
-#### `mcp-mysql_hosts`
-- **Type:** String (comma-separated)
-- **Default:** `"127.0.0.1"`
-- **Description:** Legacy POC variable used by non-routed components (for example static harvester defaults). Routed query execution uses MCP profile tables.
-- **Runtime:** Yes
-- **Example:**
-  ```sql
-  SET mcp-mysql_hosts='192.168.1.10,192.168.1.11,192.168.1.12';
-  LOAD MCP VARIABLES TO RUNTIME;
-  ```
-
-#### `mcp-mysql_ports`
-- **Type:** String (comma-separated)
-- **Default:** `"3306"`
-- **Description:** Legacy POC variable used by non-routed components (for example static harvester defaults). Routed query execution uses MCP profile tables.
-- **Runtime:** Yes
-- **Example:**
-  ```sql
-  SET mcp-mysql_ports='3306,3307,3308';
-  LOAD MCP VARIABLES TO RUNTIME;
-  ```
-
-#### `mcp-mysql_user`
-- **Type:** String
-- **Default:** `""` (empty)
-- **Description:** Legacy POC variable. Routed query execution uses credentials from `mcp_auth_profiles`.
-- **Runtime:** Yes
-- **Example:**
-  ```sql
-  SET mcp-mysql_user='mcp_user';
-  LOAD MCP VARIABLES TO RUNTIME;
-  ```
-
-#### `mcp-mysql_password`
-- **Type:** String
-- **Default:** `""` (empty)
-- **Description:** Legacy POC variable. Routed query execution uses credentials from `mcp_auth_profiles`.
-- **Runtime:** Yes
-- **Note:** Password is stored in plaintext in `global_variables`. Use restrictive MySQL user permissions.
-- **Example:**
-  ```sql
-  SET mcp-mysql_password='secure-password';
-  LOAD MCP VARIABLES TO RUNTIME;
-  ```
-
-#### `mcp-mysql_schema`
-- **Type:** String
-- **Default:** `""` (empty)
-- **Description:** Legacy POC variable. Routed query execution uses `default_schema` from `mcp_auth_profiles`.
-- **Runtime:** Yes
-- **Example:**
-  ```sql
-  SET mcp-mysql_schema='mydb';
-  LOAD MCP VARIABLES TO RUNTIME;
-  ```
-
 ### Catalog Configuration
 
 The catalog database path is **hardcoded** to `mcp_catalog.db` in the ProxySQL datadir and cannot be changed at runtime. The catalog stores:

include/MCP_Thread.h

@@ -99,12 +99,6 @@ public:
 			 * from regular MCP usage.
 			 */
 			bool mcp_stats_enable_debug_tools;
-		// MySQL Tool Handler configuration
-		char* mcp_mysql_hosts;                  ///< Comma-separated list of MySQL hosts
-		char* mcp_mysql_ports;                  ///< Comma-separated list of MySQL ports
-		char* mcp_mysql_user;                   ///< MySQL username for tool connections
-		char* mcp_mysql_password;               ///< MySQL password for tool connections
-		char* mcp_mysql_schema;                 ///< Default schema/database
 		// Catalog path is hardcoded to mcp_catalog.db in the datadir
 	} variables;
 

lib/MCP_Thread.cpp

@@ -36,12 +36,6 @@ static const char* mcp_thread_variables_names[] = {
 	"stats_show_queries_max_rows",
 	"stats_show_processlist_max_rows",
 	"stats_enable_debug_tools",
-	// MySQL Tool Handler configuration
-	"mysql_hosts",
-	"mysql_ports",
-	"mysql_user",
-	"mysql_password",
-	"mysql_schema",
 	NULL
 };
 
@@ -66,12 +60,6 @@ MCP_Threads_Handler::MCP_Threads_Handler() {
 	variables.mcp_stats_show_queries_max_rows = 200;
 	variables.mcp_stats_show_processlist_max_rows = 200;
 	variables.mcp_stats_enable_debug_tools = false;
-	// MySQL Tool Handler default values
-	variables.mcp_mysql_hosts = strdup("127.0.0.1");
-	variables.mcp_mysql_ports = strdup("3306");
-	variables.mcp_mysql_user = strdup("");
-	variables.mcp_mysql_password = strdup("");
-	variables.mcp_mysql_schema = strdup("");
 
 	status_variables.total_requests = 0;
 	status_variables.failed_requests = 0;
@@ -105,17 +93,6 @@ MCP_Threads_Handler::~MCP_Threads_Handler() {
 		free(variables.mcp_ai_endpoint_auth);
 	if (variables.mcp_rag_endpoint_auth)
 		free(variables.mcp_rag_endpoint_auth);
-	// Free MySQL Tool Handler variables
-	if (variables.mcp_mysql_hosts)
-		free(variables.mcp_mysql_hosts);
-	if (variables.mcp_mysql_ports)
-		free(variables.mcp_mysql_ports);
-	if (variables.mcp_mysql_user)
-		free(variables.mcp_mysql_user);
-	if (variables.mcp_mysql_password)
-		free(variables.mcp_mysql_password);
-	if (variables.mcp_mysql_schema)
-		free(variables.mcp_mysql_schema);
 
 	if (mcp_server) {
 		delete mcp_server;
@@ -248,27 +225,6 @@ int MCP_Threads_Handler::get_variable(const char* name, char* val) {
 		sprintf(val, "%s", variables.mcp_stats_enable_debug_tools ? "true" : "false");
 		return 0;
 	}
-	// MySQL Tool Handler configuration
-	if (!strcmp(name, "mysql_hosts")) {
-		sprintf(val, "%s", variables.mcp_mysql_hosts ? variables.mcp_mysql_hosts : "");
-		return 0;
-	}
-	if (!strcmp(name, "mysql_ports")) {
-		sprintf(val, "%s", variables.mcp_mysql_ports ? variables.mcp_mysql_ports : "");
-		return 0;
-	}
-	if (!strcmp(name, "mysql_user")) {
-		sprintf(val, "%s", variables.mcp_mysql_user ? variables.mcp_mysql_user : "");
-		return 0;
-	}
-	if (!strcmp(name, "mysql_password")) {
-		sprintf(val, "%s", variables.mcp_mysql_password ? variables.mcp_mysql_password : "");
-		return 0;
-	}
-	if (!strcmp(name, "mysql_schema")) {
-		sprintf(val, "%s", variables.mcp_mysql_schema ? variables.mcp_mysql_schema : "");
-		return 0;
-	}
 
 	return -1;
 }
@@ -393,37 +349,6 @@ int MCP_Threads_Handler::set_variable(const char* name, const char* value) {
 		}
 		return -1;
 	}
-	// MySQL Tool Handler configuration
-	if (!strcmp(name, "mysql_hosts")) {
-		if (variables.mcp_mysql_hosts)
-			free(variables.mcp_mysql_hosts);
-		variables.mcp_mysql_hosts = strdup(value);
-		return 0;
-	}
-	if (!strcmp(name, "mysql_ports")) {
-		if (variables.mcp_mysql_ports)
-			free(variables.mcp_mysql_ports);
-		variables.mcp_mysql_ports = strdup(value);
-		return 0;
-	}
-	if (!strcmp(name, "mysql_user")) {
-		if (variables.mcp_mysql_user)
-			free(variables.mcp_mysql_user);
-		variables.mcp_mysql_user = strdup(value);
-		return 0;
-	}
-	if (!strcmp(name, "mysql_password")) {
-		if (variables.mcp_mysql_password)
-			free(variables.mcp_mysql_password);
-		variables.mcp_mysql_password = strdup(value);
-		return 0;
-	}
-	if (!strcmp(name, "mysql_schema")) {
-		if (variables.mcp_mysql_schema)
-			free(variables.mcp_mysql_schema);
-		variables.mcp_mysql_schema = strdup(value);
-		return 0;
-	}
 
 	return -1;
 }