Reinstate autogenerated session

README.md

@@ -109,6 +109,7 @@ The list of DSN parameters recognized by the driver is as follows:
 |    `HugeIntAsString`    |                                                          `off`                                                           | Report integer column types that may underflow or overflow 64-bit signed integer (`SQL_BIGINT`) as a `String`/`SQL_VARCHAR`                                                                                                                                                                                                                                                                                                  |
 |       `DriverLog`       |                                  `on` if `CMAKE_BUILD_TYPE` is `Debug`, `off` otherwise                                  | Enable or disable the extended driver logging                                                                                                                                                                                                                                                                                                                                                                                |
 |     `DriverLogFile`     |               `\temp\clickhouse-odbc-driver.log`  on Windows, `/tmp/clickhouse-odbc-driver.log` otherwise                | Path to the extended driver log file (used when `DriverLog` is `on`)                                                                                                                                                                                                                                                                                                                                                         |
+| `AutoSessionId`         |                                                          `off`                                                           | Auto generate session_id required to use some features of CH (e.g. TEMPORARY TABLE)                                                                            |
 
 ### URL query string
 

driver/config/config.cpp

@@ -58,6 +58,7 @@ void readDSNinfo(ConnInfo * ci, bool overwrite) {
     GET_CONFIG(stringmaxlength, INI_STRINGMAXLENGTH, INI_STRINGMAXLENGTH_DEFAULT);
     GET_CONFIG(driverlog,       INI_DRIVERLOG,       INI_DRIVERLOG_DEFAULT);
     GET_CONFIG(driverlogfile,   INI_DRIVERLOGFILE,   INI_DRIVERLOGFILE_DEFAULT);
+    GET_CONFIG(auto_session_id, INI_AUTO_SESSION_ID, INI_AUTO_SESSION_ID_DEFAULT);
 
 #undef GET_CONFIG
 }
@@ -99,6 +100,7 @@ void writeDSNinfo(const ConnInfo * ci) {
     WRITE_CONFIG(stringmaxlength, INI_STRINGMAXLENGTH);
     WRITE_CONFIG(driverlog,       INI_DRIVERLOG);
     WRITE_CONFIG(driverlogfile,   INI_DRIVERLOGFILE);
+    WRITE_CONFIG(auto_session_id, INI_AUTO_SESSION_ID);
 
 #undef WRITE_CONFIG
 }
@@ -342,7 +344,8 @@ key_value_map_t readDSNInfo(const std::string & dsn_utf8) {
             INI_DATABASE,
             INI_STRINGMAXLENGTH,
             INI_DRIVERLOG,
-            INI_DRIVERLOGFILE
+            INI_DRIVERLOGFILE,
+            INI_AUTO_SESSION_ID
         }
     ) {
         if (

driver/config/config.h

@@ -32,6 +32,7 @@ struct ConnInfo {
     std::string stringmaxlength;
     std::string driverlog;
     std::string driverlogfile;
+    std::string auto_session_id;
 };
 
 void readDSNinfo(ConnInfo * ci, bool overwrite);

driver/config/ini_defines.h

@@ -31,6 +31,7 @@
 #define INI_STRINGMAXLENGTH "StringMaxLength"
 #define INI_DRIVERLOG       "DriverLog"
 #define INI_DRIVERLOGFILE   "DriverLogFile"
+#define INI_AUTO_SESSION_ID "AutoSessionId"
 
 #if defined(UNICODE)
 #   define INI_DSN_DEFAULT          DSN_DEFAULT_UNICODE
@@ -50,6 +51,7 @@
 #define INI_DATABASE_DEFAULT        ""
 #define INI_HUGE_INT_AS_STRING_DEFAULT "off"
 #define INI_STRINGMAXLENGTH_DEFAULT "1048575"
+#define INI_AUTO_SESSION_ID_DEFAULT "off"
 
 #ifdef NDEBUG
 #    define INI_DRIVERLOG_DEFAULT "off"

driver/connection.cpp

@@ -8,6 +8,7 @@
 #include <Poco/Net/HTTPClientSession.h>
 #include <Poco/NumberParser.h> // TODO: switch to std
 #include <Poco/URI.h>
+#include <random>
 
 #if !defined(WORKAROUND_DISABLE_SSL)
 #    include <Poco/Net/AcceptCertificateHandler.h>
@@ -47,8 +48,15 @@ void SSLInit(bool ssl_strict, const std::string & privateKeyFile, const std::str
 }
 #endif
 
+std::string GenerateSessionId() {
+    std::mt19937 generator(std::random_device{}());
+    std::uniform_int_distribution<std::uint64_t> distribution(0);
+    return std::string("clickhouse_odbc_" + std::to_string(distribution(generator)));
+}
+
 Connection::Connection(Environment & environment)
-    : ChildType(environment)
+    : ChildType(environment),
+      session_id(GenerateSessionId())
 {
     resetConfiguration();
 }
@@ -84,6 +92,7 @@ Poco::URI Connection::getUri() const {
 
     bool database_set = false;
     bool default_format_set = false;
+    bool session_id_set = false;
 
     for (const auto& parameter : uri.getQueryParameters()) {
         if (Poco::UTF8::icompare(parameter.first, "default_format") == 0) {
@@ -92,6 +101,9 @@ Poco::URI Connection::getUri() const {
         else if (Poco::UTF8::icompare(parameter.first, "database") == 0) {
             database_set = true;
         }
+        else if (Poco::UTF8::icompare(parameter.first, "session_id") == 0 && !parameter.second.empty()) {
+            session_id_set = true;
+        }
     }
 
     if (!default_format_set)
@@ -100,6 +112,12 @@ Poco::URI Connection::getUri() const {
     if (!database_set)
         uri.addQueryParameter("database", database);
 
+    // To use some features of CH (e.g. TEMPORARY TABLEs) we need a (named) session.
+    if (auto_session_id && !session_id_set) {
+        // DO not overwrite user-set session_id, just in case...
+        uri.addQueryParameter("session_id", session_id);
+    }
+
     return uri;
 }
 
@@ -379,6 +397,13 @@ void Connection::setConfiguration(const key_value_map_t & cs_fields, const key_v
                 getDriver().setAttr(CH_SQL_ATTR_DRIVERLOG, (isYes(value) ? SQL_OPT_TRACE_ON : SQL_OPT_TRACE_OFF));
             }
         }
+        else if (Poco::UTF8::icompare(key, INI_AUTO_SESSION_ID) == 0) {
+            recognized_key = true;
+            valid_value = (value.empty() || isYesOrNo(value));
+            if (valid_value) {
+                auto_session_id = isYes(value);
+            }
+        }
 
         return std::make_tuple(recognized_key, valid_value);
     };

driver/connection.h

@@ -41,6 +41,7 @@ class Connection
     std::string database;
     bool huge_int_as_string = false;
     std::int32_t stringmaxlength = 0;
+    bool auto_session_id = false;
 
 public:
     std::string useragent;

driver/test/misc_it.cpp

@@ -19,7 +19,7 @@ TEST_F(MiscellaneousTest, RowArraySizeAttribute) {
         rc = ODBC_CALL_ON_STMT_THROW(hstmt, SQLGetStmtAttr(hstmt, SQL_ATTR_ROW_ARRAY_SIZE, &size, sizeof(size), 0));
         ASSERT_EQ(size, 1);
     }
-    
+
     {
         size = 2;
         rc = ODBC_CALL_ON_STMT_THROW(hstmt, SQLSetStmtAttr(hstmt, SQL_ATTR_ROW_ARRAY_SIZE, (SQLPOINTER)size, 0));
@@ -227,7 +227,11 @@ INSTANTIATE_TEST_SUITE_P(
 
         std::make_tuple("AllGood_VerifyConnectionEarly_Empty", "VerifyConnectionEarly=",   FailOn::Never),
         std::make_tuple("AllGood_VerifyConnectionEarly_On",  "VerifyConnectionEarly=on",   FailOn::Never),
-        std::make_tuple("AllGood_VerifyConnectionEarly_Off", "VerifyConnectionEarly=off",  FailOn::Never)
+        std::make_tuple("AllGood_VerifyConnectionEarly_Off", "VerifyConnectionEarly=off",  FailOn::Never),
+
+        std::make_tuple("AllGood_AutoSessionId_Empty", "AutoSessionId=",   FailOn::Never),
+        std::make_tuple("AllGood_AutoSessionId_On",  "AutoSessionId=on",   FailOn::Never),
+        std::make_tuple("AllGood_AutoSessionId_Off", "AutoSessionId=off",  FailOn::Never)
     ),
     [] (const auto & param_info) {
         return std::get<0>(param_info.param);

packaging/odbc.ini.sample

@@ -36,6 +36,8 @@ Description = DSN (localhost) for ClickHouse ODBC Driver (ANSI)
 # DriverLog = yes
 # DriverLogFile = /tmp/chlickhouse-odbc-driver.log
 
+# AutoSessionId =  off
+
 [ClickHouse DSN (Unicode)]
 Driver      = ClickHouse ODBC Driver (Unicode)
 Description = DSN (localhost) for ClickHouse ODBC Driver (Unicode)