本文主要基于应用数据迁移，PG数据库的库、表、部分字段、自增序列如何很好地、快速有效地进行迁移。主要还是围绕原始命令展开，不涵盖三方工具，有好用的三方工具欢迎分享。
Postgres 版本： 11.4
Docker 部署
接上文:Docker部署Postgres的内容，以下将介绍如何将数据库表中的数据进行迁移。
原生的指令这边介绍两种：pg_dump、copy
内容目录：
1. PG_DUMP
能够通过外部指令，直接导出指定库、指定表的结构、数据、序列信息，可压缩，比较高效，适合大量数据提取或备份
指令参数说明如下
postgres@a:/$ pg_dump --help
pg_dump dumps a database as a text file or to other formats.
Usage:
pg_dump [OPTION]... [DBNAME]
General options:
-f, --file=FILENAME output file or directory name
-F, --format=c|d|t|p output file format (custom, directory, tar,
plain text (default))
-j, --jobs=NUM use this many parallel jobs to dump
-v, --verbose verbose mode
-V, --version output version information, then exit
-Z, --compress=0-9 compression level for compressed formats
--lock-wait-timeout=TIMEOUT fail after waiting TIMEOUT for a table lock
--no-sync do not wait for changes to be written safely to disk
-?, --help show this help, then exit
Options controlling the output content:
-a, --data-only dump only the data, not the schema
-b, --blobs include large objects in dump
-B, --no-blobs exclude large objects in dump
-c, --clean clean (drop) database objects before recreating
-C, --create include commands to create database in dump
-E, --encoding=ENCODING dump the data in encoding ENCODING
-n, --schema=SCHEMA dump the named schema(s) only
-N, --exclude-schema=SCHEMA do NOT dump the named schema(s)
-o, --oids include OIDs in dump
-O, --no-owner skip restoration of object ownership in
plain-text format
-s, --schema-only dump only the schema, no data
-S, --superuser=NAME superuser user name to use in plain-text format
-t, --table=TABLE dump the named table(s) only
-T, --exclude-table=TABLE do NOT dump the named table(s)
-x, --no-privileges do not dump privileges (grant/revoke)
--binary-upgrade for use by upgrade utilities only
--column-inserts dump data as INSERT commands with column names
--disable-dollar-quoting disable dollar quoting, use SQL standard quoting
--disable-triggers disable triggers during data-only restore
--enable-row-security enable row security (dump only content user has
access to)
--exclude-table-data=TABLE do NOT dump data for the named table(s)
--if-exists use IF EXISTS when dropping objects
--inserts dump data as INSERT commands, rather than COPY
--load-via-partition-root load partitions via the root table
--no-comments do not dump comments
--no-publications do not dump publications
--no-security-labels do not dump security label assignments
--no-subscriptions do not dump subscriptions
--no-synchronized-snapshots do not use synchronized snapshots in parallel jobs
--no-tablespaces do not dump tablespace assignments
--no-unlogged-table-data do not dump unlogged table data
--quote-all-identifiers quote all identifiers, even if not key words
--section=SECTION dump named section (pre-data, data, or post-data)
--serializable-deferrable wait until the dump can run without anomalies
--snapshot=SNAPSHOT use given snapshot for the dump
--strict-names require table and/or schema include patterns to
match at least one entity each
--use-set-session-authorization
use SET SESSION AUTHORIZATION commands instead of
ALTER OWNER commands to set ownership
Connection options:
-d, --dbname=DBNAME database to dump
-h, --host=HOSTNAME database server host or socket directory
-p, --port=PORT database server port number
-U, --username=NAME connect as specified database user
-w, --no-password never prompt for password
-W, --password force password prompt (should happen automatically)
--role=ROLENAME do SET ROLE before dump
If no database name is supplied, then the PGDATABASE environment
variable value is used.
Report bugs to <pgsql-bugs@postgresql.org>.
以上参数中，本次将使用到
- -f –file=FILENAME ：指定输出文件地址
-
-F, –format=c d t p ：选择文件内容格式(custom, directory, tar，plain text (default))，默认就是文本格式 - -a, –data-only ：选择导出-仅数据（含自增序列的增量）
- -s, –schema-only ： 选择导出-仅结构（含自增序列的定义）
- -t, –table=TABLE 仅导出哪些表
- -T, –exclude-table=TABLE 仅去除哪些表
- –column-inserts 导出为insert语句形式，而不是COPY
- -d, –dbname=DBNAME 指定库
- -h, –host=HOSTNAME 指定host
- -p, –port=PORT 连接端口
- -U, –username=NAME 访问用户名，需要是super user权限
1.1 将sms库中userinfo表结构、数据及其相关序列信息导出
pg_dump -U postgres -d sms -t userinfo -t userinfo_userid_seq -Fp -f /var/lib/postgresql/data/dumpsql/userinfoall
以上以postgres管理员用户，导出sms库中userinfo数据库、userinfo_userid_seq序列的结构+数据，到/var/lib/postgresql/data/dumpsql/userinfoall文件中
将sms库导出的数据导入sms2库：
psql -U postgres -d sms2 -f /var/lib/postgresql/data/dumpsql/userinfoall
SET
SET
SET
SET
SET
set_config
------------
(1 row)
SET
SET
SET
SET
SET
SET
CREATE TABLE
ALTER TABLE
ALTER TABLE
1.2 将sms库中userinfo表结构、序列导出
pg_dump -U postgres -d sms -t userinfo -Fp -s -f /var/lib/postgresql/data/dumpsql/userinfoschema
以上仅导出结构：
--
-- PostgreSQL database dump
--
-- Dumped from database version 11.4 (Debian 11.4-1.pgdg90+1)
-- Dumped by pg_dump version 11.4 (Debian 11.4-1.pgdg90+1)
SET statement_timeout = 0;
SET lock_timeout = 0;
SET idle_in_transaction_session_timeout = 0;
SET client_encoding = 'UTF8';
SET standard_conforming_strings = on;
SELECT pg_catalog.set_config('search_path', '', false);
SET check_function_bodies = false;
SET xmloption = content;
SET client_min_messages = warning;
SET row_security = off;
--
-- Name: userinfo_userid_seq; Type: SEQUENCE; Schema: public; Owner: test
--
CREATE SEQUENCE public.userinfo_userid_seq
START WITH 1
INCREMENT BY 1
NO MINVALUE
NO MAXVALUE
CACHE 1;
ALTER TABLE public.userinfo_userid_seq OWNER TO test;
SET default_tablespace = '';
SET default_with_oids = false;
--
-- Name: userinfo; Type: TABLE; Schema: public; Owner: test
--
CREATE TABLE public.userinfo (
userid bigint DEFAULT nextval('public.userinfo_userid_seq'::regclass) NOT NULL,
account character varying(255) NOT NULL,
appkey character varying(255)
);
ALTER TABLE public.userinfo OWNER TO test;
--
-- Name: userinfo userinfo_account_key; Type: CONSTRAINT; Schema: public; Owner: test
--
ALTER TABLE ONLY public.userinfo
ADD CONSTRAINT userinfo_account_key UNIQUE (account);
--
-- Name: userinfo userinfo_pkey; Type: CONSTRAINT; Schema: public; Owner: test
--
ALTER TABLE ONLY public.userinfo
ADD CONSTRAINT userinfo_pkey PRIMARY KEY (userid);
--
-- PostgreSQL database dump complete
--
1.3 将sms库中userinfo表数据、序列值导出
pg_dump -U postgres -d sms -t userinfo -Fp -a -f /var/lib/postgresql/data/dumpsql/userinfodata
以上仅导出数据：
--
-- PostgreSQL database dump
--
-- Dumped from database version 11.4 (Debian 11.4-1.pgdg90+1)
-- Dumped by pg_dump version 11.4 (Debian 11.4-1.pgdg90+1)
SET statement_timeout = 0;
SET lock_timeout = 0;
SET idle_in_transaction_session_timeout = 0;
SET client_encoding = 'UTF8';
SET standard_conforming_strings = on;
SELECT pg_catalog.set_config('search_path', '', false);
SET check_function_bodies = false;
SET xmloption = content;
SET client_min_messages = warning;
SET row_security = off;
--
-- Data for Name: userinfo; Type: TABLE DATA; Schema: public; Owner: test
--
COPY public.userinfo (userid, account, appkey) FROM stdin;
1 admin 21232f********c3
\.
--
-- Name: userinfo_userid_seq; Type: SEQUENCE SET; Schema: public; Owner: test
--
SELECT pg_catalog.setval('public.userinfo_userid_seq', 1, true);
--
-- PostgreSQL database dump complete
--
2. COPY
copy指令用于灵活地导出所需的数据
2.1 导出数据指令
-- 全部字段同步
COPY (select * from userinfo where userid >8 and userid < 10 ) TO '{somepath}' WITH csv;
-- 同步指定字段
COPY (select userid,username,sex,mobile from userinfo where userid >8 and userid < 10 ) TO '{somepath}' WITH csv;
2.2 导入数据指令
COPY userinfo FROM '{somepath}' WITH csv;
2.3 重置序列值
在COPY指令下，通常导入数据后，对序列值未重置，可能后面页面新增就会出现主键重复，因为需要手动重置一下序列
SELECT setval('userinfo_userid_seq', max(userid)) FROM userinfo;
