Currently in the shell, num_versions = 0 is equivalent to 'all versions'. I don't think that needs to be changed, unless someone can imagine a clause on a query that wouldn't require a version of a row to operate correctly.
Thanks, Stu -----Original Message----- From: Jim Kellerman <[EMAIL PROTECTED]> Sent: Wednesday, November 7, 2007 1:03pm To: [email protected] <[email protected]> Subject: RE: HBase num_versions num_versions=all ? --- Jim Kellerman, Senior Engineer; Powerset [EMAIL PROTECTED] > -----Original Message----- > From: Michael Stack [mailto:[EMAIL PROTECTED] > Sent: Wednesday, November 07, 2007 9:59 AM > To: [email protected] > Cc: [EMAIL PROTECTED] > Subject: Re: HBase num_versions > > In the absence of a num_versions qualifier, shell makes > presumption that you want ALL versions. Changing the default > to be 1 would mean that we would have to add some other means > of specifying all versions ("num_versions=-1" or some such > oddity). What ye think? > St.Ack > > > Jim Kellerman wrote: > > Yes, for num_versions > 1, HBase has to dig through the > memcache, and multiple HStore files until it has found the > requested number of versions or runs out of places to look. > This is especially apparent if there is only 1 version. It > has to do a lot of work for nothing. > > > > Please enter a Jira for the HBase shell to default the > number of versions to 1. > > > > --- > > Jim Kellerman, Senior Engineer; Powerset [EMAIL PROTECTED] > > > > > > > >> -----Original Message----- > >> From: Stu Hood [mailto:[EMAIL PROTECTED] > >> Sent: Tuesday, November 06, 2007 11:23 PM > >> To: [email protected] > >> Subject: HBase num_versions > >> > >> Hey guys, > >> > >> Just noticed some surprising behavior for select statements > >> in HBase 0.15: a select command without a num_versions = 1 > >> clause takes 2 orders of magnitude longer to run than a > bare select. > >> > >> Is this inconsistent implementation, or is it taking extra > >> time to scan for additional versions? If this isn't a bug, > >> then perhaps the default for num_versions should be 1 to keep > >> things snappy by default. > >> > >> ============================================================ > >> > >> Hbase> describe test; > >> +------------------------------------------------------------- > >> ----------------+ > >> | Column Family Descriptor > >> | > >> +------------------------------------------------------------- > >> ----------------+ > >> | name: hex, max versions: 3, compression: NONE, in memory: > >> false, max length:| > >> | 2147483647, bloom filter: none > >> | > >> +------------------------------------------------------------- > >> ----------------+ > >> 1 columnfamily(s) in set (0.310 sec) > >> Hbase> select hex: from test where row = '3980000' > num_versions = 1; > >> 3cbae0 > >> 1 row(s) in set (0.016 sec) > >> Hbase> select hex: from test where row = '3980000'; > >> 3cbae0 > >> 1 row(s) in set (1.882 sec) > >> > >> ============================================================ > >> > >> > >> Thanks, > >> > >> > >> Stu Hood > >> Webmail.us > >> "You manage your business. We'll manage your email."(r) > >> > >> > >> > >
