How to check if a key exists or not

[dzhou121]

Hi,

How can I just check if a key exists or not rather than return the value of the row?

Thanks

[wbolster]

I assume you want to answer the question "does row key X have any columns/values?". You can use a scanner for that, and use a filter to avoid retrieving the actual row contents (this saves network IO). Example (untested):

row_key = b'this-is-the-row-key'
scan = table.scan(
    row_start=row_key,
    filter='KeyOnlyFilter() AND FirstKeyOnlyFilter()',
    limit=1)
if next(scan, None) is not None:
    pass  # the row had at least one column/value
else:
    pass  # the row did not exist at all

See http://hbase.apache.org/book/thrift.html for more information about the available filters.

[rushton]

remember to add row_stop parameter to the scan to do a proper exists

[wbolster]

Well, just limiting it to 1 will terminate the scan.