This patch goes some way to improving recovery after an INSERT
fails. Inserts now write intermediate results to
<table_dir>/.impala_insert_staging. After execution completes, either
successfully or not, the query-specific directory under that directory
is deleted.
This doesn't complete the job for better cleanup (although this goes as
far as IMPALA-449 suggests). Two things to do in the future:
* Have each backend delete its own staging files on error. The
difficulty getting there now is that backends don't know if they are
cancelled in error or because a LIMIT was reached.
* If the operation to move files to their final destinations should
fail during FinalizeQuery(), the coordinator should perform
compensation actions and delete the files that made it.
Note: We also considered a query-wide and impalad-wide option to change
the staging dir. There are advantages to this (all intermediate results
go to a known location which is easy to clean up on failure), but also
security and other operational concerns. Worth revisiting in the future.
Change-Id: Ia54cf36db6a382e359877f87d7d40aad7fdb77be
Reviewed-on: http://gerrit.ent.cloudera.com:8080/670
Reviewed-by: Alex Behm <alex.behm@cloudera.com>
Tested-by: jenkins
The Impala CatalogService manages the caching and dissemination of cluster-wide metadata.
The CatalogService combines the metadata from the Hive Metastore, the NameNode,
and potentially additional sources in the future. The CatalogService uses the
StateStore to broadcast metadata updates across the cluster.
The CatalogService also directly handles executing metadata updates request from
impalad servers (DDL requests). It exposes a Thrift interface to allow impalads to
directly connect execute their DDL operations.
The CatalogService has two main components - a C++ server that implements StateStore
integration, Thrift service implementiation, and exporting of the debug webpage/metrics.
The other main component is the Java Catalog that manages caching and updating of of all
the metadata. For each StateStore heartbeat, a delta of all metadata updates is broadcast
to the rest of the cluster.
Some Notes On the Changes
---
* The metadata is all sent as thrift structs. To do this all catalog objects (Tables/Views,
Databases, UDFs) have thrift struct to represent them. These are sent with each statestore
delta update.
* The existing Catalog class has been seperated into two seperate sub-classes. An
ImpladCatalog and a CatalogServiceCatalog. See the comments on those classes for more
details.
What is working:
* New CatalogService created
* Working with statestore delta updates and latest UDF changes
* DDL performed on Node 1 is now visible on all other nodes without a "refresh".
* Each DDL operation against the Catalog Service will return the catalog version that
contains the change. An impalad will wait for the statestore heartbeat that contains this
version before returning from the DDL comment.
* All table types (Hbase, Hdfs, Views) getting their metadata propagated properly
* Block location information included in CS updates and used by Impalads
* Column and table stats included in CS updates and used by Impalads
* Query tests are all passing
Still TODO:
* Directly return catalog object metadata from DDL requests
* Poll the Hive Metastore to detect new/dropped/modified tables
* Reorganize the FE code for the Catalog Service. I don't think we want everything in the
same JAR.
Change-Id: I8c61296dac28fb98bcfdc17361f4f141d3977eda
Reviewed-on: http://gerrit.ent.cloudera.com:8080/601
Reviewed-by: Lenni Kuff <lskuff@cloudera.com>
Tested-by: Lenni Kuff <lskuff@cloudera.com>
OVERWRITE
INSERT OVERWRITE into an unpartitioned table is supposed to remove all
data files from the root. This should not include hidden files or
directories. This patch excludes hidden files from deletion, and adds a
test case.
Partition directories are still removed in their entirety: the cost of
statting a large number of files and directories rather than issuing a
single "rm -rf" outweighs the benefits of preserving hidden files for
now.
Hive does not preserve hidden files in either configuration.
Change-Id: Ia73e55e011c26c88f14745075210cf359764e3c1
Reviewed-on: http://gerrit.ent.cloudera.com:8080/418
Tested-by: jenkins
Reviewed-by: Lenni Kuff <lskuff@cloudera.com>
