Supported compressed sequence file for inputs in distcache_gets()

```sql
SET hive.exec.compress.output=true;
SET mapred.output.compress=true;
-- SET mapred.output.compression.type=BLOCK;
-- SET mapred.output.compression.codec=org.apache.hadoop.io.compress.GzipCodec;

create table lr_model_gzip as select * from lr_model;

SET hive.exec.compress.output=false;
-- SET mapred.output.compression.codec=org.apache.hadoop.io.compress.SnappyCodec;
```

```sql
add file hdfs://dm01:8020/user/hive/warehouse/kdd12track2.db/lr_model_gzip;

[myui@dm01 lr_model_gzip]$ ls
000000_0.gz  000002_0.gz  000004_0.gz  000006_0.gz
000001_0.gz  000003_0.gz  000005_0.gz
```

```sql
select 
  rowid, 
  distcache_gets('lr_model_gzip', features, cast(0 as float)) as weights
from 
  testing2
limit 100;
```