Database Reference
In-Depth Information
twitterkeyspace-user-jb-1-Data.db >
output.json
Here twitterkeyspace-user-jb-1-Data.db is a .db data file under the
data directory (in this case it is under /var/lib/Cassandra ). The preceding
command will create a JSON file having data as shown in Figure 10-1 .
Figure 10-1 . Data in the output.json file
We can also include and exclude specific rows using the -k and -x options, re-
spectively. With the -k option, keys have to be in hexadecimal format. Since with the
user table, the primary key is of timeuuid type, so let's first get key values in hexa-
decimal format using the timeuuidAsBlob function as follows:
select timeuuidAsBlob(user_id),fname from user;
timeuuidAsBlob(user_id) | fname
-----------------------------------------+---------
0x849d582050e311e4abc13f484de45426 | Brian
0x74ac3a8050e311e4abc13f484de45426 | Melissa
0x7c34a26050e311e4abc13f484de45426 | Chris
0xf7d1f2c050e211e4abc13f484de45426 | vivek
(4 rows)
Here timeuuidAsBlob(user_id) is the user_id key in hexadecimal
format. Now we can fetch rows having fname as brian and vivek using the -k op-
tion:
$CASSANDRA_HOME/bin/sstable2json /var/lib/cassandra/data/
twitterkeyspace/user/twitterkeyspace-user-jb-1-Data.db -k
849d582050e311e4abc13f484de45426
f7d1f2c050e211e4abc13f484de45426
[
{"key": "849d582050e311e4abc13f484de45426","columns":
 
 
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