[HBASE-14189] CF Level BC setting should override global one.

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Invalid
• Affects Version/s: 2.0.0
• Component/s: BlockCache
• External issue ID: 14178
• Assignee: Unassigned
• Reporter: Heng Chen
• Created: 06/Aug/15 09:04
• Updated: 01/Jul/22 20:49
• Resolved: 29/Jun/16 09:28

Description

The original description is ambiguous. I think i will rewrite it.
Let's see BlockCache constructor firstly

  public CacheConfig(Configuration conf, HColumnDescriptor family) {
    this(CacheConfig.instantiateBlockCache(conf),
        family.isBlockCacheEnabled(),
        family.isInMemory(),
        // For the following flags we enable them regardless of per-schema settings
        // if they are enabled in the global configuration.
        conf.getBoolean(CACHE_BLOCKS_ON_WRITE_KEY,
            DEFAULT_CACHE_DATA_ON_WRITE) || family.isCacheDataOnWrite(),
        conf.getBoolean(CACHE_INDEX_BLOCKS_ON_WRITE_KEY,
            DEFAULT_CACHE_INDEXES_ON_WRITE) || family.isCacheIndexesOnWrite(),
        conf.getBoolean(CACHE_BLOOM_BLOCKS_ON_WRITE_KEY,
            DEFAULT_CACHE_BLOOMS_ON_WRITE) || family.isCacheBloomsOnWrite(),
        conf.getBoolean(EVICT_BLOCKS_ON_CLOSE_KEY,
            DEFAULT_EVICT_ON_CLOSE) || family.isEvictBlocksOnClose(),
        conf.getBoolean(CACHE_DATA_BLOCKS_COMPRESSED_KEY, DEFAULT_CACHE_DATA_COMPRESSED),
        conf.getBoolean(PREFETCH_BLOCKS_ON_OPEN_KEY,
            DEFAULT_PREFETCH_ON_OPEN) || family.isPrefetchBlocksOnOpen(),
        conf.getBoolean(HColumnDescriptor.CACHE_DATA_IN_L1,
            HColumnDescriptor.DEFAULT_CACHE_DATA_IN_L1) || family.isCacheDataInL1(),
        conf.getBoolean(DROP_BEHIND_CACHE_COMPACTION_KEY,DROP_BEHIND_CACHE_COMPACTION_DEFAULT)
     );
  }

If we dig in it, we will see CacheConfig.cacheDataOnRead is used to accept family.isBlockCacheEnabled().
I think it is confused as comments about cacheDataOnRead

  /**
   * Whether blocks should be cached on read (default is on if there is a
   * cache but this can be turned off on a per-family or per-request basis).
   * If off we will STILL cache meta blocks; i.e. INDEX and BLOOM types.
   * This cannot be disabled.
   */
  private boolean cacheDataOnRead;

So i think we should use another variable to represent for family.isBlockCacheEnabled().

The secondary point is we use 'or' to decide cacheDataOnWrite is on/off when both CF and global has this setting.

conf.getBoolean(CACHE_BLOCKS_ON_WRITE_KEY,
            DEFAULT_CACHE_DATA_ON_WRITE) || family.isCacheDataOnWrite()

IMO we should use CF Level setting to override global setting.

Issue Links

• links to: review board