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HBqlA simple data access layer for HBase
Thursday, January 28, 2010
What is HBql?
• SQL-like Grammar
• Console
• JDBC Driver
• HBql API
Thursday, January 28, 2010
DDL Statements
• CREATE/ALTER/DROP/DESCRIBE TABLE
• CREATE/DROP/DESCRIBE INDEX
• CREATE/DROP/DESCRIBE MAPPINGS
• Predicate support for DDL
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DDL Examples
• create table tableA (f1(), f2(), f3())
• create table tableB (f1(), f2(), f3()) if not tableExists('tableB')
• create table tableC (f1(MAX_VERSIONS: 10, BLOCK_SIZE:1024*48))
• create index indexA on mappingA (f1:col1)
• create index indexB on mappingB (f1:col1) include (f1:col2, f:col3)
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Mappings
• Type info, scalar or vector
• Alias, default value
• Unmapped information
• Transient or persistent
• Multiple mappings per HTable
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Mapping Example• create temp mapping mappingA for table tableA (
keyval key, familyA include unmapped ( col1 string alias val1, col2 int alias val2 ), familyB ( col3 date alias val3, col4 int[] alias val4 ))
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DML Examples
• INSERT
• DELETE
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Insert Statement
• insert into foo (keyval, val1, val2)values (zeropad(2, 10), 123, ‘test val’)
• insert into foo (keyval, f1:val3, f1:val4)values (:a, :b, DEFAULT)
• insert into foo (keyval, f1(val3, val4))select keyval, val3, val4+‘newval’ from foo2
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Delete Statement
• delete f1:* from mappingA with server filter where val1> 3 AND val2 < 9
• delete f1:val1, val2 from mappingBwith server filter where val2 LIKE ‘foo.*bar’
• delete from mappingC with server filter where val1 IN (8, 11*3)
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Select Items
• Single table (via mapping)
• Qualified names and aliases
• Mapping and family wildcards
• Expressions (arithmetic, functions, IF, CASE)
• Aggregates
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WITH Clause
• Keys and Key Ranges
• Server and client filters
• Expressions (IN, BETWEEN, LIKE, CONTAINS)
• Versions, Limit, Timestamp, Scanner_Cache_Size
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Query Example
• select keyval, f1:val1, val2, 3+val2 as val4from mappingAwith keys FIRST to :‘ddd’, ‘eee’, ‘fff ’, ‘ggg’ to ‘ooo’server filter where val6 > 9client filter where val5 < 2versions 4limit 100
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JDBC Driver
• Connection pooling
• PreparedStatement parameters
• Cast to get to the HBql calls
• Uses HTablePool
• Uses Mappings
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HBql API
• Parallel to JDBC
• HRecord or simple object mapping
• Connection pooling
• Concurrent result set processing with Query Executor Pools
• Asynchronous queries with Async Executor Pools
• QueryListeners
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Futures
• Better docs
• Spring JDBCTemplate support
• Coprocessors integration
• Java UDFs in expressions
• Console web interface
• Feedback from users
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http://www.hbql.com
http://github.com/pambrose/HBql
http://hbql.blogspot.com
Thursday, January 28, 2010