Hive基本命令整理
建立表:
hive> CREATE TABLE pokes (foo INT, bar STRING);
Creates a table called pokes with two columns, the first being an integer and the other a string
建立一個新表,結構與其他一樣
hive> create table new_table like records;
建立分割槽表:
hive> create table logs(ts bigint,line string) partitioned by (dt String,country String);
載入分割槽表資料:
hive> load data local inpath '/home/hadoop/input/hive/partitions/file1' into table logs partition (dt='2001-01-01',country='GB');
展示表中有多少分割槽:
hive> show partitions logs;
展示所有表:
hive> SHOW TABLES;
lists all the tables
hive> SHOW TABLES '.*s';
lists all the table that end with 's'. The pattern matching follows Java regular
expressions. Check out this link for documentation
顯示錶的結構資訊
hive> DESCRIBE invites;
shows the list of columns
更新表的名稱:
hive> ALTER TABLE source RENAME TO target;
新增新一列
hive> ALTER TABLE invites ADD COLUMNS (new_col2 INT COMMENT 'a comment');
刪除表:
hive> DROP TABLE records;
刪除表中資料,但要保持表的結構定義
hive> dfs -rmr /user/hive/warehouse/records;
從本地檔案載入資料:
hive> LOAD DATA LOCAL INPATH '/home/hadoop/input/ncdc/micro-tab/sample.txt' OVERWRITE INTO TABLE records;
顯示所有函式:
hive> show functions;
檢視函式用法:
hive> describe function substr;
檢視陣列、map、結構
hive> select col1[0],col2['b'],col3.c from complex;
內連線:
hive> SELECT sales.*, things.* FROM sales JOIN things ON (sales.id = things.id);
檢視hive為某個查詢使用多少個MapReduce作業
hive> Explain SELECT sales.*, things.* FROM sales JOIN things ON (sales.id = things.id);
外連線:
hive> SELECT sales.*, things.* FROM sales LEFT OUTER JOIN things ON (sales.id = things.id);
hive> SELECT sales.*, things.* FROM sales RIGHT OUTER JOIN things ON (sales.id = things.id);
hive> SELECT sales.*, things.* FROM sales FULL OUTER JOIN things ON (sales.id = things.id);
in查詢:Hive不支援,但可以使用LEFT SEMI JOIN
hive> SELECT * FROM things LEFT SEMI JOIN sales ON (sales.id = things.id);
Map連線:Hive可以把較小的表放入每個Mapper的記憶體來執行連線操作
hive> SELECT /*+ MAPJOIN(things) */ sales.*, things.* FROM sales JOIN things ON (sales.id = things.id);
INSERT OVERWRITE TABLE ..SELECT:新表預先存在
hive> FROM records2
> INSERT OVERWRITE TABLE stations_by_year SELECT year, COUNT(DISTINCT station) GROUP BY year
> INSERT OVERWRITE TABLE records_by_year SELECT year, COUNT(1) GROUP BY year
> INSERT 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
hive>CREATE TABLE target AS SELECT col1,col2 FROM source;
建立檢視:
hive> CREATE VIEW valid_records AS SELECT * FROM records2 WHERE temperature !=9999;
檢視檢視詳細資訊:
hive> DESCRIBE EXTENDED valid_records;