Java Liquibase无法执行迁移，原因是；“重复”；PostgreSQL数据库的索引

我有一个Liquibase迁移作为我的Spring Boot应用程序的一部分来初始化我的数据库。出于开发目的，在H2内存数据库下，Liquibase执行了迁移，没有任何问题。但是，当我在PostgreSQL数据库上运行它时，Liquibase无法迁移，因为PostgreSQL返回以下内容：

原因：org.postgresql.util.PSQLException:错误：关系“idx\u channel\u id”已存在

请注意，应用索引的表是全新的，在Liquibase迁移文件中没有其他同名索引。如果我删除这个索引创建，下一个索引创建就会失败。如果我删除了索引（或者将它们移动到一个单独的迁移中，该迁移通过前提条件被排除在对PostgreSQL数据库的调用之外），迁移将成功，但根本没有索引

我一直在抓我的头在这一个，我卡住了。完全液化迁移如下：

databaseChangeLog:
  - changeSet:
      id: 1
      author: rmorrison
      changes:
        - createTable:
            tableName: shouts
            columns:
              - column:
                  name: id
                  type: bigint
                  autoIncrement: true
                  constraints:
                    primaryKey: true
                    nullable: false
              - column:
                  name: discord_id
                  type: varchar(18)
                  constraints:
                    nullable: false
              - column:
                  name: author_id
                  type: varchar(18)
                  constraints:
                    nullable: false
              - column:
                  name: channel_id
                  type: varchar(18)
                  constraints:
                    nullable: false
              - column:
                  name: guild_nickname
                  type: varchar(255)
                  constraints:
                    nullable: false
              - column:
                  name: content
                  type: varchar(2000)
                  constraints:
                    nullable: false
              - column:
                  name: created
                  type: blob
                  constraints:
                    nullable: false
        - createTable:
            tableName: contexts
            columns:
              - column:
                  name: id
                  type: bigint
                  autoIncrement: true
                  constraints:
                    primaryKey: true
                    nullable: false
              - column:
                  name: discord_id
                  type: varchar(18)
                  constraints:
                    nullable: false
              - column:
                  name: author_id
                  type: varchar(18)
                  constraints:
                    nullable: false
              - column:
                  name: guild_nickname
                  type: varchar(255)
                  constraints:
                    nullable: false
              - column:
                  name: content
                  type: varchar(2000)
                  constraints:
                    nullable: false
              - column:
                  name: created
                  type: blob
                  constraints:
                    nullable: false
        - createTable:
            tableName: shouts_contexts
            columns:
              - column:
                  name: shout_id
                  type: bigint
                  constraints:
                    nullable: false
              - column:
                  name: context_id
                  type: bigint
                  constraints:
                    nullable: false
        - createIndex:
            indexName: idx_channel_id
            tableName: shouts
            unique: false
            columns:
              - column:
                  name: channel_id
                  type: varchar(18)
        - createIndex:
            indexName: idx_author_channel_id
            tableName: shouts
            unique: false
            columns:
              - column:
                  name: author_id
                  type: varchar(18)
              - column:
                  name: channel_id
                  type: varchar(18)
        - createIndex:
            indexName: idx_content
            tableName: shouts
            unique: true
            columns:
              - column:
                  name: content
                  type: varchar(2000)

编辑：我重新配置了PostgreSQL以启用语句日志记录，现在我看到了这一点-看起来这可能根本不是Liquibase。继续调查

< 2017-05-27 19:13:19.697 EDT > LOG:  execute <unnamed>: BEGIN
< 2017-05-27 19:13:19.698 EDT > LOG:  execute <unnamed>: CREATE TABLE public.shouts (id BIGSERIAL NOT NULL, discord_id VARCHAR(18) NOT NULL, author_id VARCHAR(18) NOT NULL, channel_id VARCHAR(18) NOT NULL, guild_nickname VARCHAR(255) NOT NULL, content VARCHAR(2000) NOT NULL, created OID NOT NULL, CONSTRAINT PK_SHOUTS PRIMARY KEY (id))
< 2017-05-27 19:13:19.718 EDT > LOG:  execute <unnamed>: CREATE TABLE public.contexts (id BIGSERIAL NOT NULL, discord_id VARCHAR(18) NOT NULL, author_id VARCHAR(18) NOT NULL, guild_nickname VARCHAR(255) NOT NULL, content VARCHAR(2000) NOT NULL, created OID NOT NULL, CONSTRAINT PK_CONTEXTS PRIMARY KEY (id))
< 2017-05-27 19:13:19.725 EDT > LOG:  execute <unnamed>: CREATE TABLE public.shouts_contexts (shout_id BIGINT NOT NULL, context_id BIGINT NOT NULL)
< 2017-05-27 19:13:19.727 EDT > LOG:  execute <unnamed>: CREATE INDEX idx_channel_id ON public.shouts(channel_id)
< 2017-05-27 19:13:19.727 EDT > ERROR:  relation "idx_channel_id" already exists
< 2017-05-27 19:13:19.727 EDT > STATEMENT:  CREATE INDEX idx_channel_id ON public.shouts(channel_id)
< 2017-05-27 19:13:19.741 EDT > LOG:  execute S_1: ROLLBACK

<2017-05-27 19:13:19.697 EDT>日志：执行：开始
<2017-05-27 19:13:19.698 EDT>日志：执行：创建表public.shouts（id BIGSERIAL不为NULL，discord_id VARCHAR（18）不为NULL，author_id VARCHAR（18）不为NULL，channel_id VARCHAR（18）不为NULL，guild_昵称VARCHAR（255）不为NULL，content VARCHAR（2000）不为NULL，created OID不为NULL，CONSTRAINT PK_shouts主键（id））
<2017-05-27 19:13:19.718 EDT>LOG:execute:CREATE TABLE public.contexts（id BIGSERIAL不为NULL，discord_id VARCHAR（18）不为NULL，author_id VARCHAR（18）不为NULL，guild_昵称VARCHAR（255）不为NULL，content VARCHAR（2000）不为NULL，created OID不为NULL，CONSTRAINT PK_contexts主键（id））
<2017-05-27 19:13:19.725 EDT>日志：执行：创建表public.shouts\u上下文（shout\u id BIGINT NOT NULL，context\u id BIGINT NOT NULL）
<2017-05-27 19:13:19.727 EDT>LOG:execute:CREATE INDEX idx_channel_id ON public.shouts（channel_id）
<2017-05-27 19:13:19.727 EDT>错误：关系“idx\U通道id”已存在
<2017-05-27 19:13:19.727 EDT>声明：在公共广播上创建索引idx\U频道id（频道id）
<2017-05-27 19:13:19.741 EDT>日志：执行S_1:回滚

我解决了这个问题。事实证明，PostgreSQL要求索引名在表之间是唯一的。我有一个“备份”表，其中包含具有相同索引名的旧数据，导致了冲突。我删除了有问题的表，现在迁移成功了，没有问题