[GitHub] [iotdb] MarcosZyk commented on a diff in pull request #7977: [IOTDB-4815] Apply SchemaCache for explicit timeseries query

[GitBox <gi...@apache.org>]

MarcosZyk commented on code in PR #7977:
URL: https://github.com/apache/iotdb/pull/7977#discussion_r1022365738


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server/src/main/java/org/apache/iotdb/db/mpp/plan/analyze/ClusterSchemaFetcher.java:
##########
@@ -104,10 +106,67 @@ public ClusterSchemaTree fetchSchemaWithTags(PathPatternTree patternTree) {
   private ClusterSchemaTree fetchSchema(PathPatternTree patternTree, boolean withTags) {
     Map<Integer, Template> templateMap = new HashMap<>();
     patternTree.constructTree();
-    for (PartialPath pattern : patternTree.getAllPathPatterns()) {
+    List<PartialPath> fullPathList = new ArrayList<>();
+    List<PartialPath> pathPatternList = patternTree.getAllPathPatterns();
+    for (PartialPath pattern : pathPatternList) {
       templateMap.putAll(templateManager.checkAllRelatedTemplate(pattern));
+      if (!pattern.hasWildcard() && !withTags) {
+        fullPathList.add(pattern);
+      }
+    }
+
+    if (fullPathList.isEmpty()) {
+      return executeSchemaFetchQuery(new SchemaFetchStatement(patternTree, templateMap, withTags));
+    }
+
+    ClusterSchemaTree schemaTree;
+    if (fullPathList.size() == pathPatternList.size()) {
+      boolean isAllCached = true;
+      schemaTree = new ClusterSchemaTree();
+      String[] measurement = new String[1];
+      schemaCache.takeReadLock();
+      try {
+        ClusterSchemaTree cachedSchema;
+        for (PartialPath fullPath : fullPathList) {
+          measurement[0] = fullPath.getMeasurement();
+          cachedSchema = schemaCache.get(fullPath.getDevicePath(), measurement);
+          if (cachedSchema.isEmpty()) {
+            isAllCached = false;
+            break;
+          } else {
+            schemaTree.mergeSchemaTree(cachedSchema);
+          }
+        }
+      } finally {
+        schemaCache.releaseReadLock();
+      }
+      if (isAllCached) {
+        SchemaPartition schemaPartition = partitionFetcher.getSchemaPartition(patternTree);
+        schemaTree.setStorageGroups(
+            new ArrayList<>(schemaPartition.getSchemaPartitionMap().keySet()));
+        return schemaTree;
+      }
     }
-    return executeSchemaFetchQuery(new SchemaFetchStatement(patternTree, templateMap, withTags));
+
+    schemaTree =
+        executeSchemaFetchQuery(new SchemaFetchStatement(patternTree, templateMap, withTags));
+
+    schemaCache.takeReadLock();

Review Comment:
   The schema cache is implemented based on Caffeine which is thread safe. The readLock is added to ensure that the schema cache clean operation, taking writeLock,  executed by delete timesereis or deactivate template will be effective.



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