Well, Long.MAX_VALUE is "A constant holding the maximum value a long can have, (2^63)-1". I don't know much about ruby but I'm guessing that you could use ruby's bignum to hold that value or some value sufficiently large for your timestamp value.
-Steve -----Original Message----- From: Mark [mailto:[email protected]] Sent: Saturday, August 20, 2011 7:57 AM To: [email protected] Subject: Re: Reverse timestamp Thanks all but I'm actually using ruby as my client so there is no Long.MAX_VALUE. Apparently there is an alternative method... "These composite row keys are similar to what RDBMSs offer, yet you can control the sort order for each field separately. You could do, for example, *a bitwise inversion of the date expressed as a long value (the Linux epoch)*. This would then sort the rows descending by date" I just want to be clear on the above statement. A bitwise inversion is simply flipping the bits correct? So if the current time represented as bits is 1001110010011111100101011001110 Then the bitwise inversion is 0110001101100000011010100000110 Is this correct? On 8/20/11 7:10 AM, [email protected] wrote: > I use this bit from the link sent by Sonal: > reverse_order_stamp is an 8 byte, big endian long with a value of > (Long.MAX_VALUE - epoch). This is so the most recent stamp is at the top > rather than the bottom. > > I use (Long.MAX_VALUE - System.getCurrentTimeMillis()). > > -Steve > > -----Original Message----- > From: Mark [mailto:[email protected]] > Sent: Saturday, August 20, 2011 6:29 AM > To: [email protected] > Subject: Re: Reverse timestamp > > Thanks but I was more referring to reverse ordered timestamps for > composite keys to be used for sorting purposes. > > On 8/19/11 10:26 PM, lars hofhansl wrote: >> HBase maps (row-key, column family name, column, timestamp) to a value. >> >> The KeyValues are also sorted by the same attributes in reverse timestamp >> order. >> >> The default timestamp is the current time, but you can set any long value >> (which does not need correlate in any way to the time domain) >> as the time stamp and hence define your own ordering within multiple version >> of the same row key. >> >> See Put: Put(byte[] row, long ts). >> >> Is that what you meant? >> >> -- Lars >> >> >> >> ________________________________ >> From: Mark<[email protected]> >> To: [email protected] >> Sent: Friday, August 19, 2011 6:39 PM >> Subject: Reverse timestamp >> >> I understand the need but I don't understand how to generate a reverse >> timestamp. Can someone please explain how this is accomplished and how I can >> test that its working correctly? >> >> Thanks
