How to find the number of columns within a row key in hbase

Question

How to find the number of columns within a row key in hbase (since a row can have many columns)

Answer 1

There is a simple way:

Use hbase shell to scan through the table and write the output to a intermediate text file. Because hbase shell output splits each column of a row into a new line, we can just count the lines inside the text file (minus the first 6 lines which are hbase shell standard output and the last 2 lines).

echo "scan 'mytable', {STARTROW=>'mystartrow', ENDROW=>'myendrow'}" | hbase shell > row.txt
wc -l row.txt

Make sure to select the appropriate row keys, as the borders are not inclusive.

If you are only interested into specific columns (families), apply the filters in the hbase shell command above (e.g. FamilyFilter, ColumnRangeFilter, ...).

Answer 2

Thanks for @user3375803, actually you don't have to use external txt file. Because I can not comment on your answer, so I leave my answer below:

echo "scan 'mytable', {STARTROW=>'mystartrow', ENDROW=>'myendrow'}" | hbase shell | wc -l | awk '{print $1-8}'