[TD-10773]<enhance>: add user configurable option smlChildTableName to

specify child table name instead using ID in tag field.

src/common/inc/tglobal.h

@@ -231,6 +231,7 @@ extern int8_t tsDeadLockKillQuery;
 
 // schemaless
 extern char tsDefaultJSONStrType[];
+extern char tsSmlChildTableName[];
 
 typedef struct {
   char dir[TSDB_FILENAME_LEN];

src/common/src/tglobal.c

@@ -286,6 +286,7 @@ int8_t tsDeadLockKillQuery = 0;
 
 // default JSON string type
 char tsDefaultJSONStrType[7] = "binary";
+char tsSmlChildTableName[TSDB_TABLE_NAME_LEN] = ""; //user defined child table name can be specified in tag value. If set to empty system will generate table name using MD5 hash.
 
 int32_t (*monStartSystemFp)() = NULL;
 void (*monStopSystemFp)() = NULL;
@@ -1653,6 +1654,17 @@ static void doInitGlobalConfig(void) {
   cfg.unitType = TAOS_CFG_UTYPE_NONE;
   taosInitConfigOption(cfg);
 
+  // child talbe name specified in schemaless tag value
+  cfg.option = "smlChildTableName";
+  cfg.ptr = tsSmlChildTableName;
+  cfg.valType = TAOS_CFG_VTYPE_STRING;
+  cfg.cfgType = TSDB_CFG_CTYPE_B_CONFIG | TSDB_CFG_CTYPE_B_SHOW | TSDB_CFG_CTYPE_B_CLIENT;
+  cfg.minValue = 0;
+  cfg.maxValue = 0;
+  cfg.ptrLength = tListLen(tsSmlChildTableName);
+  cfg.unitType = TAOS_CFG_UTYPE_NONE;
+  taosInitConfigOption(cfg);
+
   // flush vnode wal file if walSize > walFlushSize and walSize > cache*0.5*blocks
   cfg.option = "walFlushSize";
   cfg.ptr = &tsdbWalFlushSize;