Hive not null探索

疑问 :

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，抱歉，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
// 表创建事件
private int createTime; // required
// 最后访问时间
private int lastAccessTime; // required
// 保留字段，默认0
private int retention; // required
// 存储相关，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
// 视图相关
private String viewOriginalText; // required
private String viewExpandedText; // required
// 表类型，管理表、外部表、虚拟视图和物化视图
private String tableType; // required
// 表的权限相关
private PrincipalPrivilegeSet privileges; // optional
// session级别的临时表，create temporary table txx(id int);
private boolean temporary; // optional
// rewrite简单来说其实就是一个SQL能不能要使用物化视图来优化查询
private boolean rewriteEnabled; // optional
// 物化视图相关，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
// 描述
private String comment; // required

是不是列中没有not null信息

设计

创建表的时候，如果配置了主键、外键、唯一索引、not null、默认值和自定义取值约束，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;
// 不支持 ALTER TABLE t_user1,t_user2 CHANGE COLUMN id id string CONSTRAINT id NOT NULL ENABLE; 所以List<SQLNotNullConstraint>中只能有一个相同的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;
    }

只分析SQLNotNullConstraint 的结构：

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

SQLNotNullConstraint 结构如下 :
// 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
// 约束名称，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的约束，开启为true，DISABLE NOVALIDATE 为false
private boolean enable_cstr; // required
// 这个字段当前只支持false NOVALIDATE，不支持VALIDATE
private boolean validate_cstr; // required
// 是否将约束用于查询优化
private boolean rely_cstr; // required

简单了解 ：

主键约束：PRIMARY KEY
取值唯一性约束：UNIQUE
非空值约束：NOT NULL
默认值约束：DEFAULT [default_value]
自定义取值约束：CHECK [check_expression]
关闭约束（可以对约束列的数据进行修改）：DISABLE NOVALIDATE
是否将约束用于查询优化：RELY/NORELY

测试结果 ：

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)]

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