Hi,
I didn't see any code about close HTable, just scaner.close.
Finish running HBase client program in a container then I restart HBase;
I found there's message zookeeper.ClientCnxn: Server connection successful
in my
container console.
I think that maybe I didn't close that table.
By adding table.close; I hope that mesage "Server connection successful"
would not appear again,
but it's not.
I guess there are still up to 2000 clients' connection to Hbase without
closing.
After that, I can't query data from hbase any more.
Any suggestions?
HTable table = new HTable(config, "myLittleHBaseTable");
// To add to a row, use Put. A Put constructor takes the name of the
row
// you want to insert into as a byte array. In HBase, the Bytes class
has
// utility for converting all kinds of java types to byte arrays. In
the
// below, we are converting the String "myLittleRow" into a byte array
to
// use as a row key for our update. Once you have a Put instance, you
can
// adorn it by setting the names of columns you want to update on the
row,
// the timestamp to use in your update, etc.If no timestamp, the server
// applies current time to the edits.
Put p = new Put(Bytes.toBytes("myLittleRow"));
// To set the value you'd like to update in the row 'myLittleRow',
specify
// the column family, column qualifier, and value of the table cell
you'd
// like to update. The column family must already exist in your table
// schema. The qualifier can be anything. All must be specified as
byte
// arrays as hbase is all about byte arrays. Lets pretend the table
// 'myLittleHBaseTable' was created with a family 'myLittleFamily'.
p.add(Bytes.toBytes("myLittleFamily"), Bytes.toBytes("someQualifier"),
Bytes.toBytes("Some Value"));
// Once you've adorned your Put instance with all the updates you want
to
// make, to commit it do the following (The HTable#put method takes the
// Put instance you've been building and pushes the changes you made
into
// hbase)
table.put(p);
// Now, to retrieve the data we just wrote. The values that come back
are
// Result instances. Generally, a Result is an object that will package
up
// the hbase return into the form you find most palatable.
Get g = new Get(Bytes.toBytes("myLittleRow"));
Result r = table.get(g);
byte [] value = r.getValue(Bytes.toBytes("myLittleFamily"),
Bytes.toBytes("someQualifier"));
// If we convert the value bytes, we should get back 'Some Value', the
// value we inserted at this location.
String valueStr = Bytes.toString(value);
System.out.println("GET: " + valueStr);
// Sometimes, you won't know the row you're looking for. In this case,
you
// use a Scanner. This will give you cursor-like interface to the
contents
// of the table. To set up a Scanner, do like you did above making a
Put
// and a Get, create a Scan. Adorn it with column names, etc.
Scan s = new Scan();
s.addColumn(Bytes.toBytes("myLittleFamily"),
Bytes.toBytes("someQualifier"));
ResultScanner scanner = table.getScanner(s);
try {
// Scanners return Result instances.
// Now, for the actual iteration. One way is to use a while loop like
so:
for (Result rr = scanner.next(); rr != null; rr = scanner.next()) {
// print out the row we found and the columns we were looking for
System.out.println("Found row: " + rr);
}
// The other approach is to use a foreach loop. Scanners are
iterable!
// for (Result rr : scanner) {
// System.out.println("Found row: " + rr);
// }
} finally {
// Make sure you close your scanners when you are done!
// Thats why we have it inside a try/finally clause
scanner.close();
}
Fleming Chiu(邱宏明)
707-6128
[email protected]
週一無肉日吃素救地球(Meat Free Monday Taiwan)
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