I'd be happy to update the docs, but need some guidance. The sytax confused me originally -- see comments on HIVE-4095 <https://issues.apache.org/jira/browse/HIVE-4095?focusedCommentId=13819885&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13819885>. I'll add this discussion to those comments.
-- Lefty On Sun, Jul 20, 2014 at 10:22 PM, Andre Araujo <ara...@pythian.com> wrote: > Indeed! The documentation is a fair bit off. > > I've tested the below on Hive 0.12 on CDH and it works fine. > Lefty, would you please update the documentation on the two pages below? > > ----------------------- > Source: > https://cwiki.apache.org/confluence/display/Hive/LanguageManual+DDL#LanguageManualDDL-ExchangePartition > "Exchange Partition" section > > {code} > ALTER TABLE source_table_name EXCHANGE PARTITION (partition_spec) WITH > TABLE target_table_name; > {code} > > This statement lets you move the data in a partition from a table to > another table that has the same schema and partition keys, but does not > already have that partition. > For details, see Exchange Partition and HIVE-4095. > > ----------------------- > Source: > https://cwiki.apache.org/confluence/display/Hive/Exchange+Partition > The EXCHANGE PARTITION DDL command has been proposed as part of > https://issues.apache.org/jira/browse/HIVE-4095. > > The syntax is: > > {code} > alter table <source_table_name> exchange partition (<partition spec>) with > table <target_table_name>; > {code} > > The partition spec can be fully or partially specified. > > The semantics of the above statement is that the data is moved from the > source table to the target table. Both the tables must have the same schema > and the same partition keys. The operation fails in the presence of an > index. > The partition(s) must exist in the source table and mus NOT exists in the > target one. Consider the following examples: > > ## Full partition spec > > {code} > create table T1(a string, b string) partitioned by (ds string); > create table T2(a string, b string) partitioned by (ds string); > alter table T1 add partition (ds = '1'); > {code} > > The operation: > > {code} > alter table T1 exchange partition (ds='1') with table T2; > {code} > > moves the data from T1 to T2@ds=1. The operation fails if T2@ds=1 already > exists or T1 and T2 have different schemas and/or partition keys. > > ## Partial partition spec > > {code} > create table T1(a string, b string) partitioned by (ds string, hr string); > create table T2(a string, b string) partitioned by (ds string, hr string); > alter table T1 add partition (ds = '1', hr = '00'); > alter table T1 add partition (ds = '1', hr = '01'); > alter table T1 add partition (ds = '1', hr = '03'); > {code} > > The operation: > > {code} > alter table T1 exchange partition (ds='1') with table T2; > {code} > > moves the 3 partitions from T1 to T2. The operation fails if any of the > partitions already exist on T2 or if T1 and T2 have different schemas > and/or partition keys. > Either all the partitions of T1 will get created or the whole operation > will fail. All partitions of T1 are dropped. > > > > On 21 July 2014 05:52, Kristof Vanbecelaere < > kristof.vanbecela...@gmail.com> wrote: > >> I think the documentation related to exchanging partitions is not accurate >> >> https://cwiki.apache.org/confluence/display/Hive/Exchange+Partition >> >> when I try it out on hortonworks sandbox 2.1 which runs Hive 0.13 I get >> this: >> >> hive> create table T1(a string, b string) partitioned by (ds string); >> >> OK >> >> Time taken: 0.72 seconds >> >> hive> create table T2(a string, b string); >> >> OK >> >> Time taken: 0.357 seconds >> >> hive> alter table T1 exchange partition (ds='1') with table T2; >> >> FAILED: SemanticException [Error 10235]: Tables have incompatible schemas >> and their partitions cannot be exchanged. >> >> > > > -- > André Araújo > Big Data Consultant/Solutions Architect > The Pythian Group - Australia - www.pythian.com > > Office (calls from within Australia): 1300 366 021 x1270 > Office (international): +61 2 8016 7000 x270 *OR* +1 613 565 8696 x1270 > Mobile: +61 410 323 559 > Fax: +61 2 9805 0544 > IM: pythianaraujo @ AIM/MSN/Y! or ara...@pythian.com @ GTalk > > “Success is not about standing at the top, it's the steps you leave behind.” > — Iker Pou (rock climber) > > -- > > > >
