Is there a jira about the design of the new file format? Sent from my iPhone
On Jan 24, 2011, at 5:40 PM, yongqiang he <heyongqiang...@gmail.com> wrote: > 4M is a good number based on a lot of experiments. Increase the number > will reduce the file size, but the saving will increase very slow > after the block size goes beyond 4M, but the perf/memory will increase > a lot. > > FYI, we are trying a new columnar file format. And it seems 4M is no > longer the magic number for this new file format. But still do not > have some number now. > > On Mon, Jan 24, 2011 at 5:03 PM, Edward Capriolo <edlinuxg...@gmail.com> > wrote: >> On Mon, Jan 24, 2011 at 7:51 PM, yongqiang he <heyongqiang...@gmail.com> >> wrote: >>> Yes. It only support block compression. (No record level compression >>> support.) >>> You can use the config 'hive.io.rcfile.record.buffer.size' to specify >>> the block size (before compression). The default is 4MB. >>> >>> Thanks >>> Yongqiang >>> On Mon, Jan 24, 2011 at 4:44 PM, Edward Capriolo <edlinuxg...@gmail.com> >>> wrote: >>>> On Mon, Jan 24, 2011 at 4:42 PM, Edward Capriolo <edlinuxg...@gmail.com> >>>> wrote: >>>>> On Mon, Jan 24, 2011 at 4:14 PM, yongqiang he <heyongqiang...@gmail.com> >>>>> wrote: >>>>>> How did you upload the data to the new table? >>>>>> You can get the data compressed by doing a insert overwrite to the >>>>>> destination table with setting "hive.exec.compress.output" to true. >>>>>> >>>>>> Thanks >>>>>> Yongqiang >>>>>> On Mon, Jan 24, 2011 at 12:30 PM, Edward Capriolo >>>>>> <edlinuxg...@gmail.com> wrote: >>>>>>> I am trying to explore some use case that I believe are perfect for >>>>>>> the columnarSerDe, tables with 100+ columns where only one or two are >>>>>>> selected in a particular query. >>>>>>> >>>>>>> CREATE TABLE (....) >>>>>>> ROW FORMAT SERDE "org.apache.hadoop.hive.serde2.columnar.ColumnarSerDe" >>>>>>> STORED AS RCFile ; >>>>>>> >>>>>>> My issue is my data from our source table, with gzip sequence files, >>>>>>> is much smaller then the ColumnarSerDe table and as a result any >>>>>>> performance gains are lost. >>>>>>> >>>>>>> Any ideas? >>>>>>> >>>>>>> Thank you, >>>>>>> Edward >>>>>>> >>>>>> >>>>> >>>>> Thank you! That was a RTFM question. >>>>> >>>>> set hive.exec.dynamic.partition.mode=nonstrict; >>>>> set hive.exec.compress.output=true; >>>>> set >>>>> mapred.output.compression.codec=org.apache.hadoop.io.compress.GzipCodec; >>>>> >>>>> I was unclear about 'STORED AS RCFile' since normally you would need >>>>> to use ' STORED AS SEQUENCEFILE' >>>>> >>>>> However >>>>> http://hive.apache.org/docs/r0.6.0/api/org/apache/hadoop/hive/ql/io/RCFile.html >>>>> explains this well. RCFILE is a special type of sequence file. >>>>> >>>>> I did get it working. Looks good compression for my table was smaller >>>>> then using GZIP BLOCK Sequence file. Query time was slightly better in >>>>> limited testing. Cool stuff. >>>>> >>>>> Edward >>>>> >>>> >>>> Do rcfiles support a blocksize for compression like other compressed >>>> sequence files? >>>> >>> >> >> Great. Do you have any suggestions or hints on how to tune this. Any >> information on what the ceiling or the floor might be? >> >> Edward >>
