The Map<byte[],Cell> is a mapping from "column" to its value(s).
A "column" is made up of the "family" and "qualifier". Notated in 0.19
as: family:qualifier
So if you iterator the RowResult:
for(Map.Entry<byte[],Cell> entry : rowResult.entrySet()) {
byte [] column = entry.getKey();
// column is of form: family:qualifier
}
0.20 splits these up in two fields so that you don't have to split/merge
all over your code. I used my own utility methods to handle the joint
family:qualifier but I think there are also methods in Bytes utility class.
Ishaaq Chandy wrote:
Thanks for the quick responses guys.
Yes, I did look at RowResult but its not very obvious what its supposed to
do when dealing with a column family that consists of multiple qualifiers.
Does each column family get a single key or does each qualifier get a single
key in the entry set?
I'm sorry, I guess I could run a test and check what it does but I am
physically away from my machine which has HBase installed so I can't verify
this - so I resorted to the documentation which didn't seem too clear to me.
Thanks again,
Ishaaq
stack-3 wrote:
On Mon, Jul 6, 2009 at 6:39 PM, Ishaaq Chandy <[email protected]> wrote:
Hmm, I have a similar requirement. However, when looking at the API I
cannot
see these classes: Get and Result. Are these 0.20.0 classes? If so, what
would be the equivalent for 0.19.3?
Yes. These are 0.20.0 classes.
In 0.19.3, use RowResult. Iterate entrySet:
http://hadoop.apache.org/hbase/docs/r0.19.3/api/org/apache/hadoop/hbase/io/RowResult.html#entrySet().
Its keyed by column.
St.Ack
Thanks,
Ishaaq
Jonathan Gray-2 wrote:
Fleming,
Of course there is!
Look at some of the different methods in Result that return various
Maps
in different format. For your example, you might do:
=======
HTable table = new HTable("Table1");
Get g = new Get(Bytes.toBytes("Key1"));
Result r = table.get(g);
// Get a Map<qualifier,value> for Family
Map<byte[],byte[]> family = r.getFamilyMap(Bytes.toBytes("Family"));
// You can get a value knowing the qualifier
byte [] value1 = family.get(Bytes.toBytes("qualifier1"));
// Or you can just iterate all the qualifiers and values
for(Map.Entry<byte[],byte[]> entry : family.entrySet()) {
byte [] qualifier = entry.getKey();
byte [] value = entry.getValue();
}
=======
All the maps that are returned by Result are NavigableMaps, so they are
sorted and allow a number of operations on them.
Hope that helps.
JG
[email protected] wrote:
Hi there,
I have a table "Table1" with one Family and 10 qualifier.
Any ways that I can get these qualifier's name in Table1,
then I can loop qualifier collection to fetch each qualifier's value.
Thank you
Fleming
====================================================================================
HTable table = new HTable(config, "Table1");
Get g = new Get(Bytes.toBytes("Key1"));
Result r = table.get(g);
byte [] value1 = r.getValue(Bytes.toBytes("Family"),
Bytes.toBytes("qualifier1"));
String valueStr1 = Bytes.toString(value1);
byte [] value2 = r.getValue(Bytes.toBytes("Family"),
Bytes.toBytes("qualifier2"));
String valueStr2 = Bytes.toString(value2);
.
.
.
byte [] value10 = r.getValue(Bytes.toBytes("Family"),
Bytes.toBytes("qualifier10"));
String valueStr10 = Bytes.toString(value10);
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