enh: optimize last pruning logic

source/common/src/systable.c

@@ -233,7 +233,7 @@ static const SSysDbTableSchema vgroupsSchema[] = {
     {.name = "v4_dnode", .bytes = 2, .type = TSDB_DATA_TYPE_SMALLINT, .sysInfo = true},
     {.name = "v4_status", .bytes = 9 + VARSTR_HEADER_SIZE, .type = TSDB_DATA_TYPE_VARCHAR, .sysInfo = true},
     {.name = "cacheload", .bytes = 4, .type = TSDB_DATA_TYPE_INT, .sysInfo = true},
-    {.name = "cacheTables", .bytes = 4, .type = TSDB_DATA_TYPE_INT, .sysInfo = true},
+    {.name = "cacheelements", .bytes = 4, .type = TSDB_DATA_TYPE_INT, .sysInfo = true},
     {.name = "tsma", .bytes = 1, .type = TSDB_DATA_TYPE_TINYINT, .sysInfo = true},
     // {.name = "compact_start_time", .bytes = 8, .type = TSDB_DATA_TYPE_TIMESTAMP, .sysInfo = false},
 };

source/dnode/vnode/src/tsdb/tsdbCacheRead.c

@@ -332,6 +332,7 @@ int32_t tsdbRetrieveCacheRows(void* pReader, SSDataBlock* pResBlock, const int32
   // retrieve the only one last row of all tables in the uid list.
   if (HASTYPE(pr->type, CACHESCAN_RETRIEVE_TYPE_SINGLE)) {
     int64_t st = taosGetTimestampUs();
+    int64_t totalMinTs = INT64_MAX;
     for (int32_t i = 0; i < pr->numOfTables; ++i) {
       STableKeyInfo* pKeyInfo = &pr->pTableList[i];
 
@@ -407,9 +408,12 @@ int32_t tsdbRetrieveCacheRows(void* pReader, SSDataBlock* pResBlock, const int32
         }
 
         if (hasNotNullRow) {
+          if (totalMinTs > minTs) {
+            totalMinTs = minTs;
+          }
           double cost = (taosGetTimestampUs() - st) / 1000.0;
           if (cost > tsCacheLazyLoadThreshold) {
-            pr->lastTs = minTs;
+            pr->lastTs = totalMinTs;
           }
         }
       }