关于hive:Hive-not-null探索

疑难 :

hive not null，是不是感觉 not null 是基于 column 的，所以就感觉 not null 是 column 中的一个字段，道歉，还真不是，口说无凭，上代码看一下

表格信息:

// 表
private String tableName; // required
// db
private String dbName; // required
// 表的所属，基于用于、者角色或者组
private String owner; // required
// 表创立事件
private int createTime; // required
// 最初拜访工夫
private int lastAccessTime; // required
// 保留字段，默认 0
private int retention; // required
// 存储相干，location,inputformat,outputformat, 序列化反序列化器
private StorageDescriptor sd; // required
// 这个就是列信息了
private List<FieldSchema> partitionKeys; // required
// table properties 信息
private Map<String,String> parameters; // required
// 视图相干
private String viewOriginalText; // required
private String viewExpandedText; // required
// 表类型，治理表、内部表、虚构视图和物化视图
private String tableType; // required
// 表的权限相干
private PrincipalPrivilegeSet privileges; // optional
// session 级别的长期表，create temporary table txx(id int);
private boolean temporary; // optional
// rewrite 简略来说其实就是一个 SQL 能不能要应用物化视图来优化查问
private boolean rewriteEnabled; // optional
// 物化视图相干，物化视图关联的表等等
private CreationMetadata creationMetadata; // optional
// 默认是 hive
private String catName; // optional
// 用户、角色或者所属组
private PrincipalType ownerType; // optional

FieldSchema 列信息:

// 列名称
private String name; // required
// 列类型
private String type; // required
// 形容
private String comment; // required

是不是列中没有 not null 信息

设计

创立表的时候 ，如果配置了主键、外键、惟一索引、not null、默认值和自定义取值束缚 ，都会走如下接口：

@Override
public void createTableWithConstraints(Table table,
                                       List<SQLPrimaryKey> primaryKeys,
                                       List<SQLForeignKey> foreignKeys,
                                       List<SQLUniqueConstraint> uniqueConstraints,
                                       List<SQLNotNullConstraint> notNullConstraints,
                                       List<SQLDefaultConstraint> defaultConstraints,
                                       List<SQLCheckConstraint> checkConstraints)
        throws AlreadyExistsException, InvalidObjectException, MetaException, NoSuchObjectException, TException {LOG.info("edap createTableWithConstraints ->  primaryKeys : {}, foreignKeys : {}, uniqueConstraints : {}, notNullConstraints : {}, defaultConstraints : {}, checkConstraints : {}",
            primaryKeys, foreignKeys, uniqueConstraints, notNullConstraints, defaultConstraints, checkConstraints);

    throw new UnsupportedOperationException("createTableWithConstraints is not supported");
}

// ALTER TABLE t_user1 CHANGE COLUMN id id string CONSTRAINT id NOT NULL ENABLE;
// 不反对 ALTER TABLE t_user1,t_user2 CHANGE COLUMN id id string CONSTRAINT id NOT NULL ENABLE; 所以 List<SQLNotNullConstraint> 中只能有一个雷同的 db 和 table
@Override
public void addNotNullConstraint(List<SQLNotNullConstraint> notNullConstraints)
            throws MetaException, NoSuchObjectException, TException {LOG.info("edap addNotNullConstraint : notNullConstraints : {}", notNullConstraints);
}

@Override
public List<SQLNotNullConstraint> getNotNullConstraints(NotNullConstraintsRequest notNullConstraintsRequest)
        throws MetaException, NoSuchObjectException, TException {return null;}

对应的获取元数据信息调用的接口是如下接口：

@Override
    public List<SQLPrimaryKey> getPrimaryKeys(PrimaryKeysRequest primaryKeysRequest)
            throws MetaException, NoSuchObjectException, TException {return null;}

    @Override
    public List<SQLForeignKey> getForeignKeys(ForeignKeysRequest foreignKeysRequest)
            throws MetaException, NoSuchObjectException, TException {return null;}

    @Override
    public List<SQLUniqueConstraint> getUniqueConstraints(UniqueConstraintsRequest uniqueConstraintsRequest)
            throws MetaException, NoSuchObjectException, TException {return null;}

    @Override
    public List<SQLNotNullConstraint> getNotNullConstraints(NotNullConstraintsRequest notNullConstraintsRequest)
            throws MetaException, NoSuchObjectException, TException {return null;}

    @Override
    public List<SQLDefaultConstraint> getDefaultConstraints(DefaultConstraintsRequest defaultConstraintsRequest)
            throws MetaException, NoSuchObjectException, TException {return null;}

    @Override
    public List<SQLCheckConstraint> getCheckConstraints(CheckConstraintsRequest checkConstraintsRequest)
            throws MetaException, NoSuchObjectException, TException {return null;}

只剖析 SQLNotNullConstraint 的构造：

@Override
public List<SQLNotNullConstraint> getNotNullConstraints(NotNullConstraintsRequest notNullConstraintsRequest)
        throws MetaException, NoSuchObjectException, TException {return null;}

SQLNotNullConstraint 构造如下 :
// 默认 hive 即可 
private String catName; // required
// db
private String table_db; // required
// 表名
private String table_name; // required
// 列名
private String column_name; // required
// 束缚名称，比如说：ALTER TABLE t_user2 CHANGE COLUMN id id1 int CONSTRAINT id_not_null NOT NULL ENABLE;
private String nn_name; // required
// 是否开启 not null 的束缚，开启为 true，DISABLE NOVALIDATE 为 false
private boolean enable_cstr; // required
// 这个字段以后只反对 false NOVALIDATE，不反对 VALIDATE
private boolean validate_cstr; // required
// 是否将束缚用于查问优化
private boolean rely_cstr; // required

简略理解：

 主键束缚：PRIMARY KEY
取值唯一性束缚：UNIQUE
非空值束缚：NOT NULL
默认值束缚：DEFAULT [default_value]
自定义取值束缚：CHECK [check_expression]
敞开束缚（能够对束缚列的数据进行批改）：DISABLE NOVALIDATE
是否将束缚用于查问优化：RELY/NORELY

测试后果：

NOT NULL : 
notNullConstraints : [SQLNotNullConstraint(catName:hive, table_db:default, table_name:constraints1, column_name:id1, nn_name:null, enable_cstr:true, validate_cstr:false, rely_cstr:false)]

NOT NULL ENABLE : 
notNullConstraints : [SQLNotNullConstraint(catName:hive, table_db:default, table_name:constraints1, column_name:id1, nn_name:null, enable_cstr:true, validate_cstr:false, rely_cstr:false)]

DISABLE NOVALIDATE RELY : 
notNullConstraints : [SQLNotNullConstraint(catName:hive, table_db:default, table_name:constraints1, column_name:id1, nn_name:null, enable_cstr:false, validate_cstr:false, rely_cstr:true)]

DISABLE NOVALIDATE NORELY : 
notNullConstraints : [SQLNotNullConstraint(catName:hive, table_db:default, table_name:constraints1, column_name:id1, nn_name:null, enable_cstr:false, validate_cstr:false, rely_cstr:false)]