Hive integration: HBase and Rcfile__HadoopSummit2010

Hive Integration: HBase and RCFile
John Sichi and Yongqiang He
Facebook

HBase Integration (John Sichi)
RCFile Integration (Yongqiang He)
Session Agenda

HBase: Facebook Warehouse Use Case
Reduce latency on dimension data availability
HBase (Dimension data) Partitioned RCFiles (Fact data) Periodic Load Continuous Update Hive Queries

HBase: Storage Handler
CREATE TABLE users(
userid int, name string, email string, notes string)
STORED BY
'org.apache.hadoop.hive.hbase.HBaseStorageHandler'
WITH SERDEPROPERTIES (
“ hbase.columns.mapping” =
“ small:name,small:email,large:notes”)
TBLPROPERTIES (
“ hbase.table.name” = “user_list”
);
INSERT, SELECT, JOIN, GROUP BY, UNION etc

Testing at scale
20-node test cluster
Bulk-loaded 6TB of gzip-compressed data from Hive into Hbase in about 30 hours
Incremental-loaded from Hive into Hbase at 30GB/hr (with write-ahead logging disabled)
Full-table scan queries: currently 5x slower than against native Hive tables (no tuning or optimization yet)
HBase: Integration Status

Retest against HBase trunk with larger (30TB) data
Try out new features for accelerating incremental load
Bulk load into table with existing data
Multiputs
Deferred logging
Support for “virtual partitions” based on timestamps
Support for deletion
Push down filters
Index join? Optimize scans?
HBase: Integration Roadmap

Why Columnar Storages
Better Compression
Light weight compression
RLE
Bit-map
Etc
CPU, Memory, Storage
Columnar Operator
Cache conscious (MonetDB)
RCFile

Why RCFile
Huge Data
Reduce data storage space required
Ad-hoc workloads
Storage space vs. speed (data performance)
Can we get both with no application changes?
Reduce storage spaces
Accelerate performance for arbitrary applications
RCFile

Pros
Work with Column Pruning
Only touch needed columns at runtime
Lazy decompression
Select col1, col2 from tbl_col_10 where col_1 > 30
Will only touch col1 and col2
Col2 is decompressed only when a block contains a col1 value greater than 30
RCFile

Cons
Row Construction
Is the main overhead
Each column’s data is stored separately, and may be sorted in different order
In memory operation for rcfile
This could be really painful; a lot of room to improve here
RCFile

Facebook Deployment
Default file format in Facebook cluster
20% space savings on average
We are transforming old data to the new format
RCFile

Future work
Support built in indexing
Like bloom filter etc
more cache conscious columnar operators
Pushing predicate to file reader
RCFile

Questions?
[email_address]
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Hive integration: HBase and Rcfile__HadoopSummit2010

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Hive integration: HBase and Rcfile__HadoopSummit2010 Presentation Transcript

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