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From: =?UTF-8?B?UHJvdXN0KFByb3VzdC9GZW5nIEd1aXpob3UpIFtTYWlwYW5dIMKt?= <pfeng@coupang.com>
Date: Mon, 24 Oct 2016 11:01:09 +0800
Message-ID: <CAC9N05k=ZyFdwL-TR81x=YsaU6zrDDxtBzDzpxMc-QV7kMPKwA@mail.gmail.com>
Subject: [In Memory] Questions about Make HBase Table In Memory
To: user@hbase.apache.org
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archived-at: Mon, 24 Oct 2016 03:01:20 -0000

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Hi, HBase Experts

I have several questions related to HBase BlockCache and IN_MEMORY setting
1. Does BlockCache cache the data when do PUT request, so next time
GET/SCAN request against the same data will be served from Memory only?
2. If HBase Table ColumnFamily have *IN_MEMORY=3Dtrue*, and every time I do
PUT  followed immediately with a GET/SCAN against the same data, assume I
have memory larger than the specific table, is that this way I can make
sure the whole table is in memory and all read requests against this table
will be served from memory only?
3. How can I determine whether a GET served from Disk Reading or Memory?
4. Compared to Item 2 above against "Prefetch Option for Blockcache", which
one is best for read performance?

The purpose I try to achieve is best and stable read performance even when
have high HDFS IO like re-balance when new servers added. we want the
performance could be comparable against memory solution like Redis.

Thanks
Proust

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