[GitHub] [hadoop-ozone] bharatviswa504 commented on issue #654: HDDS-3150. Implement getIfExist in Table and use it in CreateKey/File

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bharatviswa504 commented on issue #654: HDDS-3150. Implement getIfExist in 
Table and use it in CreateKey/File
URL: https://github.com/apache/hadoop-ozone/pull/654#issuecomment-596895075
 
 
   > Why do we need a new API for this? Can the caller not just use the isExist 
API first and then get?
   
   Because if we use isExist(), if keyMayExist returns true, then we will do 2 
times db.get
   
   isExist()
   ```
         boolean keyMayExist = db.keyMayExist(handle, key, outValue);
         if (keyMayExist) {
           boolean keyExists = (outValue.length() > 0) ||
               (db.get(handle, key) != null);
   ```
   
   Now to use in OMKeyCreateRequest
   ```
         if(omMetadataManager.getKeyTable().isExist(dbKeyName)) {
        dbKeyInfo =
             omMetadataManager.getKeyTable().getIfExist(dbKeyName);
   .
   .
   ```
   
   So if keyMayExist returns true, then we do 2 times db.get, to avoid that new 
API is introduced.
   

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