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https://issues.apache.org/jira/browse/HBASE-14189?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14996280#comment-14996280
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Heng Chen commented on HBASE-14189:
-----------------------------------
Update patch. Fix as QA suggestion.
> CF Level BC setting should override global one.
> -----------------------------------------------
>
> Key: HBASE-14189
> URL: https://issues.apache.org/jira/browse/HBASE-14189
> Project: HBase
> Issue Type: Improvement
> Components: BlockCache
> Affects Versions: 2.0.0
> Reporter: Heng Chen
> Assignee: Heng Chen
> Attachments: HBASE-14189.patch, HBASE-14189_v1.patch,
> HBASE-14189_v2.patch, HBASE-14189_v3.patch, HBASE-14189_v4.patch,
> HBASE-14189_v5.patch
>
>
> The original description is ambiguous. I think i will rewrite it.
> Let's see {{BlockCache}} constructor firstly
> {code}
> 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)
> );
> }
> {code}
> 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}}
> {code}
> /**
> * 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;
> {code}
> 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.
> {code}
> conf.getBoolean(CACHE_BLOCKS_ON_WRITE_KEY,
> DEFAULT_CACHE_DATA_ON_WRITE) || family.isCacheDataOnWrite()
> {code}
> IMO we should use CF Level setting to override global setting.
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