记一次hive版本升级

 之前的项目中hive版本用的是 apache-hive-1.2.2-bin，最近需要将hive版本升级到apache-hive-2.3.4-bin， 本来想着元数据在mysql中，直接部署好hive启动就好了，

结果提示元数据未初始化，查找一下资料，发现不同版本hive的元数据信息有所不同，而官方也给了升级方法，这里记录一下。

  首先，找到我们要升级的hive，找到apache-hive-2.3.4-bin/scripts/metastore/upgrade/mysql  这个目录

 

 

 

这个目录下有一个README，里面讲了如何升级

Hive MetaStore Upgrade HowTo

============================

 

This document describes how to upgrade the schema of a MySQL backed

Hive MetaStore instance from one release version of Hive to another

release version of Hive. For example, by following the steps listed

below it is possible to upgrade a Hive 0.5.0 MetaStore schema to a

Hive 0.7.0 MetaStore schema. Before attempting this project we

strongly recommend that you read through all of the steps in this

document and familiarize yourself with the required tools.

 

MetaStore Upgrade Steps

=======================

 

1) Shutdown your MetaStore instance and restrict access to the

   MetaStore's MySQL database. It is very important that no one else

   accesses or modifies the contents of database while you are

   performing the schema upgrade.

 

2) Create a backup of your MySQL metastore database. This will allow

   you to revert any changes made during the upgrade process if

   something goes wrong. The mysqldump utility is the easiest way to

   create a backup of a MySQL database:

 

   % mysqldump --opt <metastore_db_name> > metastore_backup.sql

 

   Note that you may need also need to specify a hostname and useame

   using the --host and --user command line switches.

 

3) Dump your metastore database schema to a file. We use the mysqldump

   utility again, but this time with a command line option that

   specifies we are only interested in dumping the DDL statements

   required to create the schema:

 

   % mysqldump --skip-add-drop-table --no-data <metastore_db_name> > my-schema-x.y.z.mysql.sql

 

4) The schema upgrade scripts assume that the schema you are upgrading

   closely matches the official schema for your particular version of

   Hive. The files in this directory with names like

   "hive-schema-x.y.z.mysql.sql" contain dumps of the official schemas

   corresponding to each of the released versions of Hive. You can

   determine differences between your schema and the official schema

   by diffing the contents of the official dump with the schema dump

   you created in the previous step. Some differences are acceptable

   and will not interfere with the upgrade process, but others need to

   be resolved manually or the upgrade scripts will fail to complete.

 

  * Missing Tables: Hive's default configuration causes the MetaStore

    to create schema elements only when they are needed. Some tables

    may be missing from your MetaStore schema if you have not created

    the corresponding Hive catalog objects, e.g. the PARTITIONS table

    will probably not exist if you have not created any table

    partitions in your MetaStore. You MUST create these missing tables

    before running the upgrade scripts. The easiest way to do this is

    by executing the official schema DDL script against your

    schema. Each of the CREATE TABLE statements in the schema script

    include an IF NOT EXISTS clause, so tables which already exist in

    your schema will be ignored, and those which don't exist will get

    created.

 

  * Extra Tables: Your schema may include a table named NUCLEUS_TABLES

    or a table named SEQUENCE_TABLE. These tables are managed

    by the DataNucleus ORM layer and will be created automatically if

    they don't exist. No action on your part is required.

 

  * Reversed Column Constraint Names in the Same Table: Tables with

    multiple constraints may have the names of the constraints

    reversed. For example, the PARTITIONS table contains two foreign

    key constraints named PARTITIONS_FK1 and PARTITIONS_FK2 which

    reference SDS.SD_ID and TBLS.TBL_ID respectively. However, in your

    schema you may find that PARTITIONS_FK1 references TBLS.TBL_ID and

    PARTITIONS_FK2 references SDS.SD_ID. Either version is acceptable

    -- the only requirement is that these constraints actually exist.

 

  * Differences in Column/Constraint Names: Your schema may contain

    tables with columns named "IDX" or unique keys named

    "UNIQUE<tab_name>". If you find either of these in your schema you

    will need to change the names to "INTEGER_IDX" and

    "UNIQUE_<tab_name>" before running the upgrade scripts. For more

    background on this issue please refer to HIVE-1435.

 

5) You are now ready to run the schema upgrade scripts. If you are

   upgrading from Hive 0.5.0 to Hive 0.6.0 you need to run the

   upgrade-0.5.0-to-0.6.0.mysql.sql script, but if you are upgrading

   from 0.5.0 to 0.7.0 you will need to run the 0.5.0 to 0.6.0 upgrade

   script followed by the 0.6.0 to 0.7.0 upgrade script.

 

   % mysql --verbose

   mysql> use <metastore_db_name>;

   Database changed

   mysql> source upgrade-0.5.0-to-0.6.0.mysql.sql

   mysql> source upgrade-0.6.0-to-0.7.0.mysql.sql

 

   These scripts should run to completion without any errors. If you

   do encounter errors you need to analyze the cause and attempt to

   trace it back to one of the preceding steps.

 

6) The final step of the upgrade process is validating your freshly

   upgraded schema against the official schema for your particular

   version of Hive. This is accomplished by repeating steps (3) and

   (4), but this time comparing against the official version of the

   upgraded schema, e.g. if you upgraded the schema to Hive 0.7.0 then

   you will want to compare your schema dump against the contents of

   hive-schema-0.7.0.mysql.sql

 

直接说主要步骤：

       一，最好先停止我们的hive相关服务，禁止访问hive的元数据 ，防止升级过程中其他应用使用修改数据。

       二，备份元数据

       三，开始升级，这里升级需要说明一下，hive提供的升级脚本是不能跨版本运行的，比如直接从1.2.2升级到2.3.4，所以我们需要根据它提供的脚本(脚本在scripts/metastore/upgrade/mysql)，一个大版本，一个大版本升级

如我这次  需要按照如下顺序执行

upgrade-1.2.0-to-2.0.0.mysql.sql

upgrade-2.0.0-to-2.1.0.mysql.sql

upgrade-2.1.0-to-2.2.0.mysql.sql

upgrade-2.2.0-to-2.3.0.mysql.sql

 

 

 

 

  执行完后，再打开我们的apache-hive-2.3.4-bin就可以了。