[Issue #524] using full path as the key in file footer cache (#525)

Author: bianhq

pixels-core/src/main/java/io/pixelsdb/pixels/core/PixelsReaderImpl.java

@@ -159,8 +159,8 @@ public PixelsReader build()
             // get PhysicalReader
             PhysicalReader fsReader = PhysicalReaderUtil.newPhysicalReader(builderStorage, builderPath);
             // try to get file tail from cache
-            String fileName = fsReader.getName();
-            PixelsProto.FileTail fileTail = builderPixelsFooterCache.getFileTail(fileName);
+            String filePath = fsReader.getPath();
+            PixelsProto.FileTail fileTail = builderPixelsFooterCache.getFileTail(filePath);
             if (fileTail == null)
             {
                 if (fsReader == null)
@@ -177,7 +177,7 @@ public PixelsReader build()
                 fsReader.seek(fileTailOffset);
                 ByteBuffer fileTailBuffer = fsReader.readFully(fileTailLength);
                 fileTail = PixelsProto.FileTail.parseFrom(fileTailBuffer);
-                builderPixelsFooterCache.putFileTail(fileName, fileTail);
+                builderPixelsFooterCache.putFileTail(filePath, fileTail);
             }
 
             // check file MAGIC and file version

pixels-core/src/main/java/io/pixelsdb/pixels/core/reader/PixelsRecordReaderImpl.java

@@ -64,7 +64,7 @@ public class PixelsRecordReaderImpl implements PixelsRecordReader
     private final List<String> cacheOrder;
     private final PixelsCacheReader cacheReader;
     private final PixelsFooterCache pixelsFooterCache;
-    private final String fileName;
+    private final String filePath;
     private final List<PixelsProto.Type> includedColumnTypes;
 
     private TypeDescription fileSchema = null;
@@ -147,7 +147,7 @@ public PixelsRecordReaderImpl(PhysicalReader physicalReader,
         this.cacheOrder = cacheOrder;
         this.cacheReader = cacheReader;
         this.pixelsFooterCache = pixelsFooterCache;
-        this.fileName = this.physicalReader.getName();
+        this.filePath = this.physicalReader.getPath();
         this.includedColumnTypes = new ArrayList<>();
         // Issue #175: this check is currently not necessary.
         // requireNonNull(TransContextCache.Instance().getQueryTransInfo(this.transId),
@@ -451,7 +451,7 @@ else if (predicate.matchesNone())
         for (int i = 0; i < targetRGNum; i++)
         {
             int rgId = targetRGs[i];
-            String rgCacheId = fileName + "-" + rgId;
+            String rgCacheId = filePath + "-" + rgId;
             PixelsProto.RowGroupFooter rowGroupFooter = pixelsFooterCache.getRGFooter(rgCacheId);
             // cache miss, read from disk and put it into cache
             if (rowGroupFooter == null)

proto/pixels.proto

@@ -35,7 +35,8 @@ option java_outer_classname = "PixelsProto";
 //         Pixel: Each column chunk contains a sequence of 'pixels'.
 //                Each pixel contains a number (e.g., 10000) of values.
 
-// The content of the file tail that must be serialized.
+// The content of the file tail that must be serialized and stored at
+// the end of each file, followed by 8 bytes
 message FileTail {
     optional Footer footer = 1;
     optional PostScript postscript = 2;