hive表存储为parquet格式_hive导出parquet

Hive0.13以后的版本

创建存储格式为parquet的hive表：

CREATE TABLE parquet_test (
 id int,
 str string,
 mp MAP<STRING,STRING>,
 lst ARRAY<STRING>,
 strct STRUCT<A:STRING,B:STRING>) 
PARTITIONED BY (part string)
STORED AS PARQUET;

测试：

本地生成parquet格式的文件

>>> import numpy as np
>>> import pandas as pd
>>> import pyarrow as pa
>>> df = pd.DataFrame({'one':['test','lisi','wangwu'], 'two': ['foo', 'bar', 'baz']})
>>> table = pa.Table.from_pandas(df)
>>> import pyarrow.parquet as pq
>>> pq.write_table(table, 'example.parquet2')
# 指定压缩格式
# 默认使用的snappy >>> pq.write_table(table, 'example.parquet2', compression='snappy')
# >>> pq.write_table(table, 'example.parquet2', compression='gzip')
# >>> pq.write_table(table, 'example.parquet2', compression='brotli')
# >>> pq.write_table(table, 'example.parquet2', compression='none')
>>> table2 = pq.read_table('example.parquet2')
>>> table2.to_pandas()
      one  two
0    test  foo
1    lisi  bar
2  wangwu  baz

Snappy压缩具有更好的性能，Gzip压缩具有更好的压缩比。

创建hive表并导入生成的parquet格式数据

hive> create table parquet_example(one string, two string) STORED AS PARQUET;
hive> load data local inpath './example.parquet2' overwrite into table parquet_example;
hive> select * from parquet_example;
OK
test	foo
lisi	bar
wangwu	baz
Time taken: 0.071 seconds, Fetched: 3 row(s)

Hive Parquet配置

hive中支持对parquet的配置,主要有:

parquet.compression
parquet.block.size
parquet.page.size

可以在Hive中直接set:

hive> set parquet.compression=snappy

控制Hive的block大小的参数:

parquet.block.size
dfs.blocksize
mapred.max.split.size

 

参考：

Python读写Parquet格式：Reading and Writing the Apache Parquet Format；

Hive支持Parquet格式：Parquet；