Hbase API 查詢（scan）

Hbase API查詢非常靈活，除了上一篇通過Get 查詢。

還可以通過Scan 查詢。scan 查詢非常的豐富場景，下面一一介紹

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• 根據行鍵的前綴進行查詢 

Scan scan = new Scan();
PrefixFilter filter1 = new PrefixFilter("rowkey8".getBytes());
scan.setFilter(filter1);
ResultScanner scanner =	htable.getScanner(scan);
print(scanner);

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•  根據startrow 及stopRow

Scan scan = new Scan();
scan.setStartRow("rowkey90".getBytes());
scan.setStopRow("rowkey95".getBytes());
ResultScanner scanner =	htable.getScanner(scan);
print(scanner);

• 分頁查詢 

Scan scan = new Scan();
PageFilter pageFilter =new PageFilter(10);
scan.setFilter(pageFilter);
scan.setStartRow("rowkey65".getBytes());
ResultScanner scanner =	htable.getScanner(scan);
print(scanner);

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• 篩選family:qualifier對應的value

Scan scan = new Scan();
SingleColumnValueFilter filter =
	new SingleColumnValueFilter("cf".getBytes(),
		"name".getBytes(),
		CompareOp.EQUAL, "name 50".getBytes());
		
	
scan.setFilter(filter);
ResultScanner scanner =	htable.getScanner(scan);
print(scanner);

 

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• 對行鍵進行過濾的， 也可以通過它來篩選出行鍵中包含指定字符串的一系列行

RowFilter 提供多個比較器

 

Scan scan = new Scan();
RowFilter filter =
		new RowFilter(CompareFilter.CompareOp.EQUAL,
						new SubstringComparator("rowkey7"));
		// rowkey regex match
RowFilter filter2 =
		new RowFilter(CompareFilter.CompareOp.EQUAL,
				new RegexStringComparator("^ro.*8.*$"));
		
		
scan.setFilter(filter2);
ResultScanner scanner =	htable.getScanner(scan);
print(scanner);