hive元数据和mysql表的对应
Hive元数据解析
本文是笔者初步整理的Hive元数据表，有不准确的地方请轻拍，后续我会补充.
1. Hive 0.11 元数据表汇总
线上Hive 0.11 metastore包括下述39个表，主要分为以下几类 ：
Database相关
Table相关
数据存储相关SDS
COLUMN相关
SERDE相关(序列化)
Partition相关(分区)
SKEW相关(数据倾斜)
BUCKET相关(分桶)
PRIVS相关(权限管理)
mysql> show tables;
+---------------------------+
| Tables_in_hive_yz_test |
+---------------------------+
| BUCKETING_COLS |
| CDS |
| COLUMNS_V2 |
| DATABASE_PARAMS |
| DBS |
| DB_PRIVS |
| GLOBAL_PRIVS |
| IDXS |
| INDEX_PARAMS |
| NUCLEUS_TABLES |
| PARTITIONS |
| PARTITION_EVENTS |
| PARTITION_KEYS |
| PARTITION_KEY_VALS |
| PARTITION_PARAMS |
| PART_COL_PRIVS |
| PART_COL_STATS |
| PART_PRIVS |
| ROLES |
| ROLE_MAP |
| SDS |
| SD_PARAMS |
| SEQUENCE_TABLE |
| SERDES |
| SERDE_PARAMS |
| SKEWED_COL_NAMES |
| SKEWED_COL_VALUE_LOC_MAP |
| SKEWED_STRING_LIST |
| SKEWED_STRING_LIST_VALUES |
| SKEWED_VALUES |
| SORT_COLS |
| TABLE_PARAMS |
| TAB_COL_STATS |
| TBLS |
| TBL_COL_PRIVS |
| TBL_PRIVS |
| TYPES |
| TYPE_FIELDS |
| VERSION |
+---------------------------+
39 rows in set (0.00 sec)
2.各个表的含义
2.1 Database表:DBS
描述 该表存储Hive Database的元数据信息，DB_ID是数据库ID,NAME是库名,DB_LOCATION_URI是数据库在HDFS中的位置，DESC为数据库的描述信息。
mysql> desc DBS;
+-----------------+---------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------------+---------------+------+-----+---------+-------+
| DB_ID | bigint(20) | NO | PRI | NULL | |
| DESC | varchar(4000) | YES | | NULL | |
| DB_LOCATION_URI | varchar(4000) | NO | | NULL | |
| NAME | varchar(128) | YES | UNI | NULL | |
+-----------------+---------------+------+-----+---------+-------+
例子：acorn_3g数据库的信息如下，表示该库ID为81，路径为hdfs://YZSJHL19-42.opi.com/warehouse.test/acorn_3g.db
mysql> select * from DBS where NAME='acorn_3g';
+-------+------+-------------------------------------------------------+----------+
| DB_ID | DESC | DB_LOCATION_URI | NAME |
+-------+------+-------------------------------------------------------+----------+
| 81 | NULL | hdfs://YZSJHL19-42.opi.com/warehouse.test/acorn_3g.db | acorn_3g |
+-------+------+-------------------------------------------------------+----------+
2. 2 Table 表
描述:
TBLS 存储Hive Table的元数据信息,每个表有唯一的TBL_ID
SD_ID外键指向所属的Database,SD_IID关联SDS表的主键。 其中SDS存储列(CD_ID)等信息。TBLS.SD_ID关联SDS.SD_ID, SDS.SD_ID关联CDS.CD_ID,
CDS.CD_ID关联COLUMNS_V2.CD_ID
例子：*acorn_3g.user_act表的信息: TBL_ID为41231，TBL_TYPE为MANAGED_TABLE普通表(若值为EXTERNAL,表示外部表),DB_ID为81,表示隶属DB_ID=81的Database。
mysql> select * from TBLS where TBL_NAME='user_act' and DB_ID=81 \G
*************************** 1. row ***************************
TBL_ID: 41231
CREATE_TIME: 1366188055
DB_ID: 81
LAST_ACCESS_TIME: 0
OWNER: xianbing.liu
RETENTION: 0
SD_ID: 263311
TBL_NAME: user_act
TBL_TYPE: MANAGED_TABLE
VIEW_EXPANDED_TEXT: NULL
VIEW_ORIGINAL_TEXT: NULL
2.3 SDS表(数据存储表)
描述:
SDS表保存了Hive数据仓库所有的HDFS数据文件信息，每个SD_ID唯一标记一个数据存储记录
CD_ID关联COLUMN_V2.CD_ID，指定该数据的字段信息
SERDE_ID关联SERDES.SERDE_ID，指定该数据的序列化信息(如是否是序列化表，DELIMITED字段等)
例子：
根据SDS表找到acorn_3g.user_act表的CD_ID是263311, SERDE_ID是263301,默认存储位置为
hdfs://YZSJHL19-42.opi.com/warehouse.test/acorn_3g.db/user_act
mysql> select * from SDS where SD_ID=263311 \G
*************************** 1. row ***************************
SD_ID: 263311
CD_ID: 263311
INPUT_FORMAT: org.apache.hadoop.mapred.TextInputFormat
IS_COMPRESSED:
LOCATION: hdfs://YZSJHL19-42.opi.com/warehouse.test/acorn_3g.db/user_act
NUM_BUCKETS: -1
OUTPUT_FORMAT: org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat
SERDE_ID: 263301
IS_STOREDASSUBDIRECTORIES:
2.4 CDS 和 COLUMN_V2 (列信息)
CDS表
描述:
该表只有一个字段CD_ID，永远存储整个Hive数据仓库中的CD_ID.
例子:
可以看到acorn_3g.user_act表对应的CD_ID记录在CDS中
mysql> desc CDS;
+-------+------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+------------+------+-----+---------+-------+
| CD_ID | bigint(20) | NO | PRI | NULL | |
+-------+------------+------+-----+---------+-------+
1 row in set (0.00 sec)
mysql> select * FROM CDS where CD_ID=263311;
+--------+
| CD_ID |
+--------+
| 263311 |
+--------+
1 row in set (0.00 sec)
COLUMN_V2表
描述:
该表存储了一个CD_ID对应的所有字段信息
例子:
查看acorn_3g.user_act表的COLUMN信息;我们可以看到acorn_3g.user_act表有14个字段，COLUMN_NAME为字段名，TYPE_NAME为字段类型,INTEGER_IDX为字段序号
mysql> select * from COLUMNS_V2 where CD_ID=263311 order by integer_idx;
+--------+---------+---------------+-----------+-------------+
| CD_ID | COMMENT | COLUMN_NAME | TYPE_NAME | INTEGER_IDX |
+--------+---------+---------------+-----------+-------------+
| 263311 | NULL | id | bigint | 0 |
| 263311 | NULL | action_id | int | 1 |
| 263311 | NULL | user_id | bigint | 2 |
| 263311 | NULL | request | string | 3 |
| 263311 | NULL | visit_time | string | 4 |
| 263311 | NULL | source_id | int | 5 |
| 263311 | NULL | sess_id | string | 6 |
| 263311 | NULL | mobile_number | string | 7 |
| 263311 | NULL | from_id | string | 8 |
| 263311 | NULL | app_id | string | 9 |
| 263311 | NULL | version | string | 10 |
| 263311 | NULL | reg_type | int | 11 |
| 263311 | NULL | uniqid | string | 12 |
| 263311 | NULL | failure | int | 13 |
+--------+---------+---------------+-----------+-------------+
2.5 SERDES和SERDE_PARAMS (序列化)
描述:
SERDES存储了所有的序列化信息(SERDE_ID,SLIB),SLIB表示序列化所采用的Java类
SERDES_PARAMS 存储序列化具体的参数及值
例子： acorn_3g.user_act表对应的SERDE_ID=263301表示 采用hive默认序列化类org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe , DELIMITED字符为'\t' (即创建表时指定的 ...DELIMITED BY '\t' ...)
mysql> select * FROM SERDES where SERDE_ID=263301;
+----------+------+----------------------------------------------------+
| SERDE_ID | NAME | SLIB |
+----------+------+----------------------------------------------------+
| 263301 | NULL | org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe |
+----------+------+----------------------------------------------------+
mysql> select SERDE_ID,PARAM_KEY,REPLACE(PARAM_VALUE,'\t','\\t') from SERDE_PARAMS where SERDE_ID=263301;
+----------+----------------------+---------------------------------+
| SERDE_ID | PARAM_KEY | REPLACE(PARAM_VALUE,'\t','\\t') |
+----------+----------------------+---------------------------------+
| 263301 | field.delim | \t |
| 263301 | serialization.format | \t |
+----------+----------------------+---------------------------------+
2.6 PARTITIONS PARTITION_KEY 和 PARTITION_KEY_VALS (分区)
PARTITION_KEYS
描述:
PARTITION_KEYS 保存了所有分区表用于分区的字段
例子:
通过PARTITION_KEYS查看acorn_3g.user_act的分区信息，可看到该表是一个分区表，分区字段为log_date,其中INTEGER_IDX为分区字段的序号，和分区字段一一对应
mysql> desc PARTITION_KEYS;
+--------------+---------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+--------------+---------------+------+-----+---------+-------+
| TBL_ID | bigint(20) | NO | PRI | NULL | |
| PKEY_COMMENT | varchar(4000) | YES | | NULL | |
| PKEY_NAME | varchar(128) | NO | PRI | NULL | |
| PKEY_TYPE | varchar(767) | NO | | NULL | |
| INTEGER_IDX | int(11) | NO | | NULL | |
+--------------+---------------+------+-----+---------+-------+
mysql> select * FROM PARTITION_KEYS WHERE TBL_ID=41231;
+--------+--------------+-----------+-----------+-------------+
| TBL_ID | PKEY_COMMENT | PKEY_NAME | PKEY_TYPE | INTEGER_IDX |
+--------+--------------+-----------+-----------+-------------+
| 41231 | NULL | log_date | string | 0 |
+--------+--------------+-----------+-----------+-------------+
PARTITIONS
描述:
PARTITIONS存储了Hive数据仓库总所有的分区信息，每个分区由PART_ID标识，其中TBL_ID为隶属的Table,SD_ID为隶属的SDS(见2.3)
例子:
通过PARTITIONS表查看acorn_3g.user_act表的分区信息，如PART_ID为168301，名字为log_date=2013-03-01,SD_ID为231621
mysql> desc PARTITIONS;
+------------------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+------------------+--------------+------+-----+---------+-------+
| PART_ID | bigint(20) | NO | PRI | NULL | |
| CREATE_TIME | int(11) | NO | | NULL | |
| LAST_ACCESS_TIME | int(11) | NO | | NULL | |
| PART_NAME | varchar(767) | YES | MUL | NULL | |
| SD_ID | bigint(20) | YES | MUL | NULL | |
| TBL_ID | bigint(20) | YES | MUL | NULL | |
+------------------+--------------+------+-----+---------+-------+
mysql> select * FROM PARTITIONS WHERE TBL_ID=41231 order by PART_NAME limit 5;
+---------+-------------+------------------+---------------------+--------+--------+
| PART_ID | CREATE_TIME | LAST_ACCESS_TIME | PART_NAME | SD_ID | TBL_ID |
+---------+-------------+------------------+---------------------+--------+--------+
| 168301 | 1366259946 | 0 | log_date=2013-03-01 | 231621 | 41231 |
| 168321 | 1366260063 | 0 | log_date=2013-03-02 | 231641 | 41231 |
| 168331 | 1366260176 | 0 | log_date=2013-03-03 | 231651 | 41231 |
| 168346 | 1366260298 | 0 | log_date=2013-03-04 | 231666 | 41231 |
| 168361 | 1366260398 | 0 | log_date=2013-03-05 | 231681 | 41231 |
+---------+-------------+------------------+---------------------+--------+--------+
PARTITION_KEY_VALS
描述：
PARTITION_KEY_VALS 存储了PARTITION_KEY中描述的分区字段的值，通常配合PARTITIONS 和PARTITION_KEYS表使用。
例子:
查看分区PART_ID=168301各分区字段的值，其中PARTITION_KEY_VALS存储了所有分区字段序号(INTEGER_IDX)和值(PART_KEY_VAL)间的对应关系。本例中acorn_3g.user_act PART_ID=168301分区log_date字段的值为‘2013-03-01’
mysql> select pk.PKEY_NAME,pk.PKEY_TYPE,pk.INTEGER_IDX,pkv.PART_KEY_VAL from PARTITION_KEYS pk,PARTITION_KEY_VALS pkv
where pk.INTEGER_IDX=pkv.INTEGER_IDX and pk.TBL_ID=41231 and pkv.PART_ID=168301;
+-----------+-----------+-------------+--------------+
| PKEY_NAME | PKEY_TYPE | INTEGER_IDX | PART_KEY_VAL |
+-----------+-----------+-------------+--------------+
| log_date | string | 0 | 2013-03-01 |
+-----------+-----------+-------------+--------------+
2.7 BUCKET 相关表
描述
BUCKETING_COLS表描述了所有采用了分桶技术的SDS,目前公司未用BUCKET,//TODO
mysql> desc BUCKETING_COLS;
+-----------------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------------+--------------+------+-----+---------+-------+
| SD_ID | bigint(20) | NO | PRI | NULL | |
| BUCKET_COL_NAME | varchar(256) | YES | | NULL | |
| INTEGER_IDX | int(11) | NO | PRI | NULL | |
+-----------------+--------------+------+-----+---------+-------+
2.8 PRIVS 权限管理相关表
TBL_PRIVS DB_PRIVS PART_PRIVS 等，目前Hive在权限管理方面远不及关系数据库，公司也未对权限进行统一管理。
2.9 SKEW 数据倾斜相关表
相比0.8版本，0.11元数据增加了数据倾斜相关的表 SKEWED_COL_NAMES SKEWED_COL_VALUE_LOC_MAP SKEWED_STRING_LIST SKEWED_STRING_LIST_VALUES SKEWED_VALUES ，这些高级特性还在测试阶段，目前公司没有用到。
2.3 其他
如VERSION 描述版本信息，这类表开发者不用太关心。
本文是笔者初步整理的Hive元数据表，有不准确的地方请轻拍，后续我会补充.
1. Hive 0.11 元数据表汇总
线上Hive 0.11 metastore包括下述39个表，主要分为以下几类 ：
Database相关
Table相关
数据存储相关SDS
COLUMN相关
SERDE相关(序列化)
Partition相关(分区)
SKEW相关(数据倾斜)
BUCKET相关(分桶)
PRIVS相关(权限管理)
mysql> show tables;
+---------------------------+
| Tables_in_hive_yz_test |
+---------------------------+
| BUCKETING_COLS |
| CDS |
| COLUMNS_V2 |
| DATABASE_PARAMS |
| DBS |
| DB_PRIVS |
| GLOBAL_PRIVS |
| IDXS |
| INDEX_PARAMS |
| NUCLEUS_TABLES |
| PARTITIONS |
| PARTITION_EVENTS |
| PARTITION_KEYS |
| PARTITION_KEY_VALS |
| PARTITION_PARAMS |
| PART_COL_PRIVS |
| PART_COL_STATS |
| PART_PRIVS |
| ROLES |
| ROLE_MAP |
| SDS |
| SD_PARAMS |
| SEQUENCE_TABLE |
| SERDES |
| SERDE_PARAMS |
| SKEWED_COL_NAMES |
| SKEWED_COL_VALUE_LOC_MAP |
| SKEWED_STRING_LIST |
| SKEWED_STRING_LIST_VALUES |
| SKEWED_VALUES |
| SORT_COLS |
| TABLE_PARAMS |
| TAB_COL_STATS |
| TBLS |
| TBL_COL_PRIVS |
| TBL_PRIVS |
| TYPES |
| TYPE_FIELDS |
| VERSION |
+---------------------------+
39 rows in set (0.00 sec)
2.各个表的含义
2.1 Database表:DBS
描述 该表存储Hive Database的元数据信息，DB_ID是数据库ID,NAME是库名,DB_LOCATION_URI是数据库在HDFS中的位置，DESC为数据库的描述信息。
mysql> desc DBS;
+-----------------+---------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------------+---------------+------+-----+---------+-------+
| DB_ID | bigint(20) | NO | PRI | NULL | |
| DESC | varchar(4000) | YES | | NULL | |
| DB_LOCATION_URI | varchar(4000) | NO | | NULL | |
| NAME | varchar(128) | YES | UNI | NULL | |
+-----------------+---------------+------+-----+---------+-------+
例子：acorn_3g数据库的信息如下，表示该库ID为81，路径为hdfs://YZSJHL19-42.opi.com/warehouse.test/acorn_3g.db
mysql> select * from DBS where NAME='acorn_3g';
+-------+------+-------------------------------------------------------+----------+
| DB_ID | DESC | DB_LOCATION_URI | NAME |
+-------+------+-------------------------------------------------------+----------+
| 81 | NULL | hdfs://YZSJHL19-42.opi.com/warehouse.test/acorn_3g.db | acorn_3g |
+-------+------+-------------------------------------------------------+----------+
2. 2 Table 表
描述:
TBLS 存储Hive Table的元数据信息,每个表有唯一的TBL_ID
SD_ID外键指向所属的Database,SD_IID关联SDS表的主键。 其中SDS存储列(CD_ID)等信息。TBLS.SD_ID关联SDS.SD_ID, SDS.SD_ID关联CDS.CD_ID,
CDS.CD_ID关联COLUMNS_V2.CD_ID
例子：*acorn_3g.user_act表的信息: TBL_ID为41231，TBL_TYPE为MANAGED_TABLE普通表(若值为EXTERNAL,表示外部表),DB_ID为81,表示隶属DB_ID=81的Database。
mysql> select * from TBLS where TBL_NAME='user_act' and DB_ID=81 \G
*************************** 1. row ***************************
TBL_ID: 41231
CREATE_TIME: 1366188055
DB_ID: 81
LAST_ACCESS_TIME: 0
OWNER: xianbing.liu
RETENTION: 0
SD_ID: 263311
TBL_NAME: user_act
TBL_TYPE: MANAGED_TABLE
VIEW_EXPANDED_TEXT: NULL
VIEW_ORIGINAL_TEXT: NULL
2.3 SDS表(数据存储表)
描述:
SDS表保存了Hive数据仓库所有的HDFS数据文件信息，每个SD_ID唯一标记一个数据存储记录
CD_ID关联COLUMN_V2.CD_ID，指定该数据的字段信息
SERDE_ID关联SERDES.SERDE_ID，指定该数据的序列化信息(如是否是序列化表，DELIMITED字段等)
例子：
根据SDS表找到acorn_3g.user_act表的CD_ID是263311, SERDE_ID是263301,默认存储位置为
hdfs://YZSJHL19-42.opi.com/warehouse.test/acorn_3g.db/user_act
mysql> select * from SDS where SD_ID=263311 \G
*************************** 1. row ***************************
SD_ID: 263311
CD_ID: 263311
INPUT_FORMAT: org.apache.hadoop.mapred.TextInputFormat
IS_COMPRESSED:
LOCATION: hdfs://YZSJHL19-42.opi.com/warehouse.test/acorn_3g.db/user_act
NUM_BUCKETS: -1
OUTPUT_FORMAT: org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat
SERDE_ID: 263301
IS_STOREDASSUBDIRECTORIES:
2.4 CDS 和 COLUMN_V2 (列信息)
CDS表
描述:
该表只有一个字段CD_ID，永远存储整个Hive数据仓库中的CD_ID.
例子:
可以看到acorn_3g.user_act表对应的CD_ID记录在CDS中
mysql> desc CDS;
+-------+------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+------------+------+-----+---------+-------+
| CD_ID | bigint(20) | NO | PRI | NULL | |
+-------+------------+------+-----+---------+-------+
1 row in set (0.00 sec)
mysql> select * FROM CDS where CD_ID=263311;
+--------+
| CD_ID |
+--------+
| 263311 |
+--------+
1 row in set (0.00 sec)
COLUMN_V2表
描述:
该表存储了一个CD_ID对应的所有字段信息
例子:
查看acorn_3g.user_act表的COLUMN信息;我们可以看到acorn_3g.user_act表有14个字段，COLUMN_NAME为字段名，TYPE_NAME为字段类型,INTEGER_IDX为字段序号
mysql> select * from COLUMNS_V2 where CD_ID=263311 order by integer_idx;
+--------+---------+---------------+-----------+-------------+
| CD_ID | COMMENT | COLUMN_NAME | TYPE_NAME | INTEGER_IDX |
+--------+---------+---------------+-----------+-------------+
| 263311 | NULL | id | bigint | 0 |
| 263311 | NULL | action_id | int | 1 |
| 263311 | NULL | user_id | bigint | 2 |
| 263311 | NULL | request | string | 3 |
| 263311 | NULL | visit_time | string | 4 |
| 263311 | NULL | source_id | int | 5 |
| 263311 | NULL | sess_id | string | 6 |
| 263311 | NULL | mobile_number | string | 7 |
| 263311 | NULL | from_id | string | 8 |
| 263311 | NULL | app_id | string | 9 |
| 263311 | NULL | version | string | 10 |
| 263311 | NULL | reg_type | int | 11 |
| 263311 | NULL | uniqid | string | 12 |
| 263311 | NULL | failure | int | 13 |
+--------+---------+---------------+-----------+-------------+
2.5 SERDES和SERDE_PARAMS (序列化)
描述:
SERDES存储了所有的序列化信息(SERDE_ID,SLIB),SLIB表示序列化所采用的Java类
SERDES_PARAMS 存储序列化具体的参数及值
例子： acorn_3g.user_act表对应的SERDE_ID=263301表示 采用hive默认序列化类org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe , DELIMITED字符为'\t' (即创建表时指定的 ...DELIMITED BY '\t' ...)
mysql> select * FROM SERDES where SERDE_ID=263301;
+----------+------+----------------------------------------------------+
| SERDE_ID | NAME | SLIB |
+----------+------+----------------------------------------------------+
| 263301 | NULL | org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe |
+----------+------+----------------------------------------------------+
mysql> select SERDE_ID,PARAM_KEY,REPLACE(PARAM_VALUE,'\t','\\t') from SERDE_PARAMS where SERDE_ID=263301;
+----------+----------------------+---------------------------------+
| SERDE_ID | PARAM_KEY | REPLACE(PARAM_VALUE,'\t','\\t') |
+----------+----------------------+---------------------------------+
| 263301 | field.delim | \t |
| 263301 | serialization.format | \t |
+----------+----------------------+---------------------------------+
2.6 PARTITIONS PARTITION_KEY 和 PARTITION_KEY_VALS (分区)
PARTITION_KEYS
描述:
PARTITION_KEYS 保存了所有分区表用于分区的字段
例子:
通过PARTITION_KEYS查看acorn_3g.user_act的分区信息，可看到该表是一个分区表，分区字段为log_date,其中INTEGER_IDX为分区字段的序号，和分区字段一一对应
mysql> desc PARTITION_KEYS;
+--------------+---------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+--------------+---------------+------+-----+---------+-------+
| TBL_ID | bigint(20) | NO | PRI | NULL | |
| PKEY_COMMENT | varchar(4000) | YES | | NULL | |
| PKEY_NAME | varchar(128) | NO | PRI | NULL | |
| PKEY_TYPE | varchar(767) | NO | | NULL | |
| INTEGER_IDX | int(11) | NO | | NULL | |
+--------------+---------------+------+-----+---------+-------+
mysql> select * FROM PARTITION_KEYS WHERE TBL_ID=41231;
+--------+--------------+-----------+-----------+-------------+
| TBL_ID | PKEY_COMMENT | PKEY_NAME | PKEY_TYPE | INTEGER_IDX |
+--------+--------------+-----------+-----------+-------------+
| 41231 | NULL | log_date | string | 0 |
+--------+--------------+-----------+-----------+-------------+
PARTITIONS
描述:
PARTITIONS存储了Hive数据仓库总所有的分区信息，每个分区由PART_ID标识，其中TBL_ID为隶属的Table,SD_ID为隶属的SDS(见2.3)
例子:
通过PARTITIONS表查看acorn_3g.user_act表的分区信息，如PART_ID为168301，名字为log_date=2013-03-01,SD_ID为231621
mysql> desc PARTITIONS;
+------------------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+------------------+--------------+------+-----+---------+-------+
| PART_ID | bigint(20) | NO | PRI | NULL | |
| CREATE_TIME | int(11) | NO | | NULL | |
| LAST_ACCESS_TIME | int(11) | NO | | NULL | |
| PART_NAME | varchar(767) | YES | MUL | NULL | |
| SD_ID | bigint(20) | YES | MUL | NULL | |
| TBL_ID | bigint(20) | YES | MUL | NULL | |
+------------------+--------------+------+-----+---------+-------+
mysql> select * FROM PARTITIONS WHERE TBL_ID=41231 order by PART_NAME limit 5;
+---------+-------------+------------------+---------------------+--------+--------+
| PART_ID | CREATE_TIME | LAST_ACCESS_TIME | PART_NAME | SD_ID | TBL_ID |
+---------+-------------+------------------+---------------------+--------+--------+
| 168301 | 1366259946 | 0 | log_date=2013-03-01 | 231621 | 41231 |
| 168321 | 1366260063 | 0 | log_date=2013-03-02 | 231641 | 41231 |
| 168331 | 1366260176 | 0 | log_date=2013-03-03 | 231651 | 41231 |
| 168346 | 1366260298 | 0 | log_date=2013-03-04 | 231666 | 41231 |
| 168361 | 1366260398 | 0 | log_date=2013-03-05 | 231681 | 41231 |
+---------+-------------+------------------+---------------------+--------+--------+
PARTITION_KEY_VALS
描述：
PARTITION_KEY_VALS 存储了PARTITION_KEY中描述的分区字段的值，通常配合PARTITIONS 和PARTITION_KEYS表使用。
例子:
查看分区PART_ID=168301各分区字段的值，其中PARTITION_KEY_VALS存储了所有分区字段序号(INTEGER_IDX)和值(PART_KEY_VAL)间的对应关系。本例中acorn_3g.user_act PART_ID=168301分区log_date字段的值为‘2013-03-01’
mysql> select pk.PKEY_NAME,pk.PKEY_TYPE,pk.INTEGER_IDX,pkv.PART_KEY_VAL from PARTITION_KEYS pk,PARTITION_KEY_VALS pkv
where pk.INTEGER_IDX=pkv.INTEGER_IDX and pk.TBL_ID=41231 and pkv.PART_ID=168301;
+-----------+-----------+-------------+--------------+
| PKEY_NAME | PKEY_TYPE | INTEGER_IDX | PART_KEY_VAL |
+-----------+-----------+-------------+--------------+
| log_date | string | 0 | 2013-03-01 |
+-----------+-----------+-------------+--------------+
2.7 BUCKET 相关表
描述
BUCKETING_COLS表描述了所有采用了分桶技术的SDS,目前公司未用BUCKET,//TODO
mysql> desc BUCKETING_COLS;
+-----------------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------------+--------------+------+-----+---------+-------+
| SD_ID | bigint(20) | NO | PRI | NULL | |
| BUCKET_COL_NAME | varchar(256) | YES | | NULL | |
| INTEGER_IDX | int(11) | NO | PRI | NULL | |
+-----------------+--------------+------+-----+---------+-------+
2.8 PRIVS 权限管理相关表
TBL_PRIVS DB_PRIVS PART_PRIVS 等，目前Hive在权限管理方面远不及关系数据库，公司也未对权限进行统一管理。
2.9 SKEW 数据倾斜相关表
相比0.8版本，0.11元数据增加了数据倾斜相关的表 SKEWED_COL_NAMES SKEWED_COL_VALUE_LOC_MAP SKEWED_STRING_LIST SKEWED_STRING_LIST_VALUES SKEWED_VALUES ，这些高级特性还在测试阶段，目前公司没有用到。
2.3 其他
如VERSION 描述版本信息，这类表开发者不用太关心。