About Row_prefix parameters in Happybase

Cause: When using Happybase to access HBase

    def scan (self, row_start=none, Row_stop=none, Row_prefix=none,             Columns=none, Filter=none, Timestamp=none             , Include_timestamp=false, batch_size=1000, Scan_batching=none,             Limit=none, Sorted_columns=false):

There is a row_prefix parameter in the scan function, and this parameter does not appear in the Java Client counterpart function, what does it do?

View the source code, we can see

        If Row_prefix is not none:            if Row_start are not none or Row_stop are not none:                raise TypeError (                    "' Row_prefix ' CA Nnot be combined with ' Row_start ' ""                    or ' row_stop ' ")            Row_start = row_prefix            row_stop = str_increment (row_ Prefix

Specific code for Str_increment

def str_increment (s): "" "    increment and truncate a byte string (for sorting purposes) This    functions returns the SH Ortest string, sorts after the given    string, when compared using regular string comparison semantics.    This function increments the last byte, which is smaller than "0xFF", and    drops everything after it. If the string only contains ' 0xFF ' bytes,    ' None ' is returned.    "" For i in Xrange (Len (s)-1,-1,-1):        if s[i]! = ' \xff ':            return s[:i] + chr (ORD (s[i]) + 1)    return None

After reading the code, we should understand that Row_prefix was converted into Row_start and row_stop.

When you have the following scenario

Micro-Blog Watch

User id_ Weibo ID

Assuming we want to get all of this user's Weibo, there is no need to set the scan range ' user id_0 ' ~ ' user id_a ' on scan

And you can use Row_prefix = ' user ID' directly

PS: I will provide str_increment Java implementation later.

About Row_prefix parameters in Happybase