Changes between Version 3 and Version 4 of waue/2010/0128


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Timestamp:
Jan 29, 2010, 5:40:58 PM (14 years ago)
Author:
waue
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  • waue/2010/0128

    v3 v4  
    22#!html
    33<div style="text-align: center; color:#151B8D"><big style="font-weight: bold;"><big><big>
    4 HBase Indexed Table
     4HBase Primary Table  v.s. Indexed Table
    55</big></big></big></div> <div style="text-align: center; color:#7E2217"><big style="font-weight: bold;"><big>
    6 Using HBase TableIndexed from Thrift with unique keys
     6 Indexed Table = Secondary Index = Transactional HBase
    77</big></big></div>
    88}}}
    99[[PageOutline]]
    1010
     11= what is secondary index (distinguished to primary index) =
     12
     13Explain what is primary and secondary index.
     14
     15When you activate an object say ODS / DSO, the system automatically generate an index based on the key fields and this is primary index.
     16
     17In addition if you wish to create more indexes , then they are called secondary indexes.
     18
     19The primary index is distinguished from the secondary indexes of a table. The primary index contains the key fields of the table and a pointer to the non-key fields of the table. The primary index is created automatically when the table is created in the database.
     20
     21You can also create further indexes on a table. These are called secondary indexes. This is necessary if the table is frequently accessed in a way that does not take advantage of the sorting of the primary index for the access. Different indexes on the same table are distinguished with a three-place index identifier.
     22
     23 = secondary index on hbase  =
     24
    1125[http://kdpeterson.net/blog/2009/09/using-hbase-tableindexed-from-thrift-with-unique-keys.html]
    1226
    1327HBase is primarily a sorted distributed hash map, but it does support secondary keys through a contrib package called Transactional HBase. The secondary keys are provided by a component called TableIndexed.
    1428
     29
     30 = hbase's secondary index detail =
    1531[http://mail-archives.apache.org/mod_mbox/hadoop-hbase-user/200908.mbox/%3C73d592f60908180339j3231f7f5w688260109ab3463@mail.gmail.com%3E]
    16 
    17 = what is secondary index (distinguished in primary index) =
    18 
    19 Explain the what is primary and secondary index.
    20 
    21 When you activate an object say ODS / DSO, the system automatically generate an index based on the key fields and this is primary index.
    22 
    23 In addition if you wish to create more indexes , then they are called secondary indexes.
    24 
    25 The primary index is distinguished from the secondary indexes of a table. The primary index contains the key fields of the table and a pointer to the non-key fields of the table. The primary index is created automatically when the table is created in the database.
    26 
    27 You can also create further indexes on a table. These are called secondary indexes. This is necessary if the table is frequently accessed in a way that does not take advantage of the sorting of the primary index for the access. Different indexes on the same table are distinguished with a three-place index identifier.
    28 
    29  = hbase's secondary index detail =
    3032
    3133{{{