mnode/table: separate table id prefix from mnodeRetrieveShowTables

prep for cross db create table checking in mnodeDoCreateChildTable

src/common/inc/tname.h

@@ -25,6 +25,8 @@ void extractTableName(const char *tableId, char *name);
 
 char* extractDBName(const char *tableId, char *name);
 
+int32_t tableIdPrefix(const char* pDb, char* prefix, int32_t len);
+
 void extractTableNameFromToken(SStrToken *pToken, SStrToken* pTable);
 
 SSchema tGetTableNameColumnSchema();

src/common/src/tname.c

@@ -39,6 +39,13 @@ char* extractDBName(const char* tableId, char* name) {
   return strncpy(name, &tableId[offset1 + 1], len);
 }
 
+int32_t tableIdPrefix(const char* name, char* prefix, int32_t len) {
+  tstrncpy(prefix, name, len);
+  strcat(prefix, TS_PATH_DELIMITER);
+
+  return strlen(prefix);
+}
+
 SSchema tGetTableNameColumnSchema() {
   SSchema s = {0};
   s.bytes = TSDB_TABLE_NAME_LEN - 1 + VARSTR_HEADER_SIZE;

src/mnode/src/mnodeTable.c

@@ -2629,9 +2629,7 @@ static int32_t mnodeRetrieveShowTables(SShowObj *pShow, char *data, int32_t rows
   SPatternCompareInfo info = PATTERN_COMPARE_INFO_INITIALIZER;
 
   char prefix[64] = {0};
-  tstrncpy(prefix, pDb->name, 64);
-  strcat(prefix, TS_PATH_DELIMITER);
-  int32_t prefixLen = strlen(prefix);
+  int32_t prefixLen = tableIdPrefix(pDb->name, prefix, 64);
 
   char* pattern = NULL;
   if (pShow->payloadLen > 0) {