HiveQL基本操作整理

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1. 建立操作1.1 建立表

CREATE TABLE pokes (foo INT, bar STRING);

1.2 基於現有的表結構建立一個新表

create table new_table like records;

1.3 建立視圖：

CREATE VIEW valid_records AS SELECT * FROM records2 WHERE temperature !=9999;

1.4 建立外部表格：

CREATE EXTERNAL TABLE page_view(viewTime INT, userid BIGINT,     page_url STRING, referrer_url STRING,     ip STRING COMMENT ‘IP Address of the User‘,     country STRING COMMENT ‘country of origination‘)COMMENT ‘This is the staging page view table‘ROW FORMAT DELIMITED FIELDS TERMINATED BY ‘\054‘STORED AS TEXTFILELOCATION ‘<hdfs_location>‘;

1.5 建分區表：

CREATE TABLE par_table(viewTime INT, userid BIGINT,     page_url STRING, referrer_url STRING,     ip STRING COMMENT ‘IP Address of the User‘)COMMENT ‘This is the page view table‘PARTITIONED BY(date STRING, pos STRING)ROW FORMAT DELIMITED fields terminated by ‘\t‘lines terminated by ‘\n‘;STORED AS SEQUENCEFILE;

2. 載入資料

hive不支援用insert語句一條一條的進行插入操作，也不支援update操作。資料是以load的方式載入到建立好的表中。資料一旦匯入就不可以修改。
路徑支援:
* 相對路徑，例如：project/data1
* 絕對路徑，例如： /user/hive/project/data1
* 包含模式的完整 URI，例如：hdfs://namenode:9000/user/hive/project/data1

2.1 從本地檔案載入資料：

LOAD DATA LOCAL INPATH ‘/home/hadoop/input/ncdc/micro-tab/sample.txt‘ OVERWRITE INTO TABLE records;

2.2 載入分區表資料：

load data local inpath ‘/home/hadoop/input/hive/partitions/file1‘ into table logs partition (dt=‘2001-01-01‘,country=‘GB‘);

3. 查看錶結構3.1 展示所有表：

SHOW TABLES;SHOW TABLES ‘.*s‘; //按正條件（Regex）顯示表

3.2 顯示表的結構資訊

DESCRIBE invites;

3.3 展示表中有多少分區：

show partitions logs;

3.4 顯示所有函數：

show functions;

3.5 查看函數用法：

describe function substr;

3.6 查看數組、map、結構

select col1[0],col2[‘b‘],col3.c from complex;

3.7 查看hive為某個查詢使用多少個MapReduce作業

Explain SELECT sales.*, things.* FROM sales JOIN things ON (sales.id = things.id);

3.8 查看視圖詳細資料：

DESCRIBE EXTENDED valid_records;

4. 更新操作4.1 更新表的名稱：

ALTER TABLE source RENAME TO target;

4.2 添加、更新一列

ALTER TABLE invites ADD|REPLACE COLUMNS (new_col2 INT COMMENT ‘a comment‘);

4.3 增加、刪除分區

ALTER TABLE table_name ADD [IF NOT EXISTS] partition_spec [ LOCATION ‘location1‘ ] partition_spec [ LOCATION ‘location2‘ ] ...      partition_spec:  : PARTITION (partition_col = partition_col_value, partition_col = partiton_col_value, ...)ALTER TABLE table_name DROP partition_spec, partition_spec,...

4.4 增加表的中繼資料資訊

ALTER TABLE table_name SET TBLPROPERTIES table_properties table_properties:     :[property_name = property_value…..]

4.5 改變表檔案格式與組織

ALTER TABLE table_name SET FILEFORMAT file_formatALTER TABLE table_name CLUSTERED BY(userid) SORTED BY(viewTime) INTO num_buckets BUCKETS

5. 刪除操作5.1 刪除表：

DROP TABLE records;

5.2 刪除表中資料，但要保持表的結構定義

dfs -rmr /user/hive/warehouse/records;

5.3 刪除視圖

DROP VIEW view_name

6. 串連操作6.1 內串連：

SELECT sales.*, things.* FROM sales JOIN things ON (sales.id = things.id);

6.2 外串連：

SELECT sales.*, things.* FROM sales LEFT OUTER JOIN things ON (sales.id = things.id);SELECT sales.*, things.* FROM sales RIGHT OUTER JOIN things ON (sales.id = things.id);SELECT sales.*, things.* FROM sales FULL OUTER JOIN things ON (sales.id = things.id);

6.3 in查詢：Hive不支援，但可以使用LEFT SEMI JOIN

SELECT * FROM things LEFT SEMI JOIN sales ON (sales.id = things.id);

6.4 Map串連：Hive可以把較小的表放入每個Mapper的記憶體來執行串連操作

SELECT /*+ MAPJOIN(things) */ sales.*, things.* FROM sales JOIN things ON (sales.id = things.id);

INSERT OVERWRITE TABLE ..SELECT：新表預先存在

FROM records2INSERT OVERWRITE TABLE stations_by_year SELECT year, COUNT(DISTINCT station) GROUP BY yearINSERT OVERWRITE TABLE records_by_year SELECT year, COUNT(1) GROUP BY yearINSERT OVERWRITE TABLE good_records_by_year SELECT year, COUNT(1) WHERE temperature != 9999 AND (quality = 0 OR quality = 1 OR quality = 4 OR quality = 5 OR quality = 9) GROUP BY year;  

CREATE TABLE … AS SELECT：新表表預先不存在

CREATE TABLE target AS SELECT col1,col2 FROM source;

7. 插入資料7.1 基本模式

 INSERT OVERWRITE TABLE tablename1 [PARTITION (partcol1=val1, partcol2=val2 ...)] select_statement1 FROM from_statement

7.2 多插入模式

FROM from_statementINSERT OVERWRITE TABLE tablename1 [PARTITION (partcol1=val1, partcol2=val2 ...)] select_statement1[INSERT OVERWRITE TABLE tablename2 [PARTITION ...] select_statement2] ...

7.3 自動分區模式

INSERT OVERWRITE TABLE tablename PARTITION (partcol1[=val1], partcol2[=val2] ...) select_statement FROM from_statement

8. 匯出資料到HDFS

資料寫入檔案系統時進行文本序列化，且每列用^A 來區分，\n換行

INSERT OVERWRITE [LOCAL] DIRECTORY directory1 SELECT ... FROM ...        FROM from_statement        INSERT OVERWRITE [LOCAL] DIRECTORY directory1 select_statement1     [INSERT OVERWRITE [LOCAL] DIRECTORY directory2 select_statement2]

HiveQL基本操作整理