1.配置参数的更改

1.1.增加参数

参数名称	描述	默认值
enable_gathermerge	Enable execution plan Gather Merge (user)	on
max_parallel_workers	Maximum number of parallel worker process (user)	8
max_sync_workers_per_subscription	Maximum number of synchronous workers for SUBSCRIPTION (sighup)	2
wal_consistency_checking	Check the consistency of WAL on the standby instance (superuser)	-
max_logical_replication_workers	Maximum number of Logical Replication worker process (postmaster)	4
max_pred_locks_per_relation	Maximum number of pages that can be Predicate-Lock before locking the entire relation (sighup)	-2
max_pred_locks_per_page	Maximum number of records that can be Predicate-Lock before locking the entire page (sighup)	2
min_parallel_table_scan_size	Minimum table size at which Parallel table scan are considered (user)	8MB
min_parallel_index_scan_size	Minimum table size at which Parallel index scan are considered (user)	512kB

• max_parallel_workers

指定可以在实例中并发运行的并行查询工作进程的最大数量。默认值为 8。在旧版本中，max_worker_processes 参数是上限。如果此值设置为 0，则并行查询无效。

• max_logical_replication_workers

指定要为每个 SUBSCRIPTION 启动的 Logical Replication Worker 进程的最大值。即使该参数的值小于要求的值，CREATE SUBSCRIPTION 语句也不会失败。复制开始时会定期输出以下日志。

WARNING:  out of logical replication worker slots 
HINT:  You might need to increase max_logical_replication_workers. 

• wal_consistency_checking

此参数用于复制环境中 WAL 重新执行程序的错误检查。对于参数，请使用逗号 （，） 分隔符指定要检查的对象类型。以下值可用：all、hash、heap、heap 2、btree、gin、gist、sequence、spgist、brin、generic。

• max_pred_locks_per_page

指定要转换为页锁的最大 Tuples 锁数。

• max_pred_locks_per_relation

指定要转换为关系锁的最大页锁数。

1.2.调整参数

参数名称	调整
ssl	The value of the context column has been changed to sighup
ssl_ca_file	The value of the context column has been changed to sighup
ssl_cert_file	The value of the context column has been changed to sighup
ssl_ciphers	The value of the context column has been changed to sighup
ssl_crl_file	The value of the context column has been changed to sighup
ssl_ecdh_curve	The value of the context column has been changed to sighup
ssl_key_file	The value of the context column has been changed to sighup
ssl_prefer_server_ciphers	The value of the context column has been changed to sighup
bgwriter_lru_maxpages	The value of max_val column was changed to INT_MAX / 2
archive_timeout	The value of the short_desc column has changed
server_version_num	The value of max_val / min_val column was changed to 100021
password_encryption	The value of the vartype was changed to enum. “md5” or “scram-sha-256” can specified. “on” is a alias for “md5”
max_wal_size	The value of the unit column has been changed to 1MB
min_wal_size	The value of the unit column has been changed to 1MB

1.3.参数默认值改变

参数名称	PostgreSQL 9.6	PostgreSQL 10
hot_standby	off	on
log_line_prefix	‘’	%m [%p]
max_parallel_workers_per_gather	0	2
max_replication_slots	0	10
max_wal_senders	0	10
password_encryption	on	md5
server_version	9.6.3	10.21
server_version_num	90603	100021
wal_level	minimal	replica
log_directory	pg_log	log

1.4.移除的参数

参数名称	替代值
min_parallel_relation_size	Changed to min_parallel_table_scan_size
sql_inheritance	None (same as ‘on’)

1.5.认证方式新功能

对 pg_hba.conf 文件进行了以下更改。

• 指定 RADIUS 服务器

RADIUS 身份验证所需的 RADIUS 服务器规格从radiusserver 改为 radiusservers。可以指定多个服务器，以逗号分隔。

• 添加了 SCRAM 身份验证

可以在 pg_hba.conf 中为身份验证方法指定 Scram-sha-256。这是一个RFC 5802 和 7677 中指定的 SCRAM-SHA-256 的实施。Scram-sha-256 也可以是为配置参数 password_encryption 指定。

1.6.本地认证默认值

pg_hba.conf 文件中包含的与复制相关的默认值已更改。默认情况下，本地连接设置为 “trust” 设置。

# Allow replication connections from localhost, by a user with the
# replication privilege.
local   replication     all                                     trust
host    replication     all             127.0.0.1/32            trust
host    replication     all             ::1/128                 trust

1.7.其他参数调整

与 “Point In Time Recovery” 相关的参数 recovery_target_lsn 已添加到 recovery.conf 文件中。对于此参数，请指定恢复完成 LSN。

2.实用程序改变

2.1.psql

• \d command

更改了 d 命令输出的表信息格式。通常使用的 “Modifier” 列已分为 Collation、Nullable 和 Default。

PostgreSQL 9.6

postgres=> \d data1 
		Table "public.data1" 
Column |         Type          | Modifiers 
--------+-----------------------+----------- 
c1     | numeric     | default 1           
c2     | character varying(10) | not null

PostgreSQL 10

postgres=> \d data1 
		Table "public.data1" 
Column |         Type          | Collation | Nullable | Default 
--------+-----------------------+-----------+----------+--------- 
c1     | numeric     | default 1|           |           | 1          
c2     | character varying(10) |           | not null |

• \timing 命令的其他信息

timing 命令控制 SQL 语句执行时间的输出。在新版本中，执行时间输出中添加了易于理解的时间格式。当 SQL 执行时间小于 1 秒时，输出格式与旧版本相同。

postgres=> \timing 
Timing is on. 
postgres=> INSERT INTO data1 values (generate_series(1, 10000000)) ; 
INSERT 0 10000000 
Time: 61086.012 ms (01:01.086)

• \gx command

\gx 命令以扩展格式重新运行最近执行的 SQL 语句。

postgres=> SELECT * FROM data1 ; 
 c1 |  c2 ----+------ 
  1 | data 
(1 row) 
 
postgres=> \gx -[ RECORD 1 ] 
c1 | 1 
c2 | data

• \set command

postgres=# \set
AUTOCOMMIT = 'on'
COMP_KEYWORD_CASE = 'preserve-upper'
DBNAME = 'postgres'
ECHO = 'none'
ECHO_HIDDEN = 'off'
...

• \if, \elif, \else, \endif command

现在可以在 psql 命令中执行条件分支。可以在 if、else 和 endif 之间执行条件分支，并且两者之间的命令被视为一个块。
对于 If command 和 elif command，必须指定可以确定 True 或 False 的参数。也可以嵌套条件语句。

postgres=# create table customer (customer_id int);
CREATE TABLE
postgres=# create table employee (employee_id int);
CREATE TABLE
postgres=# insert into customer values(123);
INSERT 0 1
postgres=# SELECT 
EXISTS(SELECT 1 FROM customer WHERE customer_id=123) AS is_customer, 
EXISTS(SELECT 1 FROM employee WHERE employee_id=456) AS is_employee \gset 
\if :is_customer 
SELECT * FROM customer WHERE customer_id = 123 ; 
\elif :is_employee 
SELECT * FROM employee WHERE employee_id = 456 ; 
\endif

2.2.pg_ctl

pg_ctl 命令中新增了以下函数。

• promote等待

pg_ctl 命令可以指定选项 ‘-w’ 以等待备用实例被提升。之前版本需要参考 trigger 文件来确认 promote 完成。

• 为选项添加了别名

--wait 和 --no-wait 可以用作选项 -w 和 -W 的别名。此外，--options 可以是
用于 “-o” 指定选项。

• 等待启动 （-w） 默认
  默认情况下，所有操作都已变为等待操作完成 （--wait）。之前版本实例启动和提升处理的默认行为未等待操作完成。

2.3.pg_basebackup

• 更改默认模式

备份 WAL 的默认方式是 Stream。说明默认备份的时候同时进行WAL的备份。

• 停止使用 -x 选项

-x 选项（--xlog 选项）已弃用。

• 更改 -X 选项

对于 -X 选项，值 “none” 表示事务日志不包含在备份中。长选项名称已从 --xlog-method更改为 --wal-method。

• 更改 --xlogdir 选项

选项名称已从 --xlogdir 更改为 --waldir。

• -Ft 选项和 -Xstream 选项组合

将备份数据输出到 tar 文件 -Ft 的选项和 -Xstream 选项现在可以同时使用
时间。在这种情况下pg_wal.tar，事务日志存储在
output 的 -D 选项。

PostgreSQL 9.6

$ pg_basebackup -D backup -v --format=t ---xlog-method=stream 
pg_basebackup: WAL streaming can only be used in plain mode
Try "pg_basebackup --help" for more information.

PostgreSQL 10

$ pg_basebackup -D backup -v -Ft -Xstream 
pg_basebackup: initiating base backup, waiting for checkpoint to complete 
pg_basebackup: checkpoint completed 
… 
pg_basebackup: waiting for background process to finish streaming ... 
pg_basebackup: base backup completed 
$ ls backup/ 
base.tar  pg_wal.tar 
$ tar tvf back1/pg_wal.tar -rw------- postgres/postgres        
$ -rw------- postgres/postgres 16777216 2024-12-02 16:36 0000001000000000000002F 
0 2024-12-02 16:36 
archive_status/000000010000000000000

• 临时复制槽

如果未指定槽名称 （-S）（并且未指定 --no-slot），则使用临时复制槽。以下是log_replication_commands参数设置为 “on” 时的日志。临时槽已创建以 pg_basebackup_ 开头的名称。

LOG:  received replication command: IDENTIFY_SYSTEM 
LOG:  received replication command: BASE_BACKUP LABEL 'pg_basebackup 
base backup'    
NOWAIT 
LOG:  received replication command: IDENTIFY_SYSTEM 
LOG:  received replication command: CREATE_REPLICATION_SLOT 
"pg_basebackup_12889" TEMPORARY PHYSICAL RESERVE_WAL 
LOG:  received replication command: START_REPLICATION SLOT 
"pg_basebackup_12889" 0/49000000 TIMELINE 1

如果复制槽已满，则创建复制槽将失败pg_basebackup因此命令将失败。请检查参数max_replication_slots 是否有可用空间。

$ pg_basebackup -D backup2/
pg_basebackup: could not create temporary replication slot "pg_basebackup_64": ERROR:  all replication slots are in use
HINT:  Free one or increase max_replication_slots.
pg_basebackup: child process exited with exit code 1
pg_basebackup: removing contents of data directory "backup2/"
$ echo $? 
1

• 出错时清理

当 pg_basebackup 命令期间发生错误或接收到信号时，将删除 -D 参数指定目录中的文件。如果不需要删除操作，请可以指定参数 --no-clean（或 -n）。

• --verbose 模式

指定参数 --verbose（或 -v）时，将显示更详细的信息。

$ pg_basebackup  -D backup2 --verbose 
pg_basebackup: initiating base backup, waiting for checkpoint to complete 
pg_basebackup: checkpoint completed 
pg_basebackup: write-ahead log start point: 0/35000028 on timeline 1 
pg_basebackup: starting background WAL receiver 
pg_basebackup: write-ahead log end point: 0/35000130 
$ 
pg_basebackup: waiting for background process to finish streaming ... 
pg_basebackup: base backup completed

2.4.pg_dump

新增了下面的option

• -B (--no-blobs)

Exclude large objects

• --no-subscriptions

Exclude SUBSCRIPTION objects used for Logical Replication

• --no-publications

Exclude PUBLICATION objects used for Logical Replication

• --no-sync

Does not execute sync system call after writing file. By default, the sync call is executed to
ensure a reliable write operation.

2.5.pg_dumpall

新增了下面的option

• --no-sync

Does not execute sync system call after writing file. By default, the sync call is executed to
ensure a reliable write operation.

• --no-role-passwords

Does not dump role’s password.

• --no-subscriptions

Exclude SUBSCRIPTION objects used for Logical Replication

• --no-publications

Exclude PUBLICATION objects used for Logical Replication

2.6.pg_recvlogical

添加了 -E 选项（--endpos 选项），用于在收到指定的 LSN 后终止程序

$ pg_recvlogical -d postgres --endpos=0/3016A20 --slot slot1 --start --file=output_file

2.7.pgbench

添加了 “--log-prefix” 参数来更改日志文件的前缀字符串。默认值与以前的版本一样为 “pgbench_log”。除了上述内容外，还有一些新功能是提供给 pgbench 命令，但尚未进行验证。

$ pgbench --log-prefix benchmark_2024_test --log  --client=10 --transactions=1000 -s 10 postgres
scale option ignored, using count from pgbench_branches table (10)
starting vacuum...end.
transaction type: <builtin: TPC-B (sort of)>
scaling factor: 10
query mode: simple
number of clients: 10
number of threads: 1
number of transactions per client: 1000
number of transactions actually processed: 10000/10000
latency average = 3.237 ms
tps = 3088.974257 (including connections establishing)
tps = 3091.521662 (excluding connections establishing)
$ ls
benchmark_2024_test.102
$ cat benchmark_2024_test.102 
1 0 5895 0 1733294707 112264
2 0 6199 0 1733294707 112587
1 1 1586 0 1733294707 113849
0 0 10027 0 1733294707 116361
...

2.8.initdb

“--noclean” 和 “--nosync” 选项已更改为 “--no-clean” 和 “--no-sync” 选项。

2.9.pg_receivexlog

命令的名称已更改为 pg_receivewal。现在可以指定 --compress 参数来压缩输出 WAL 文件。压缩比可以指定为 0 到 9。为了使用此功能，必须在安装了 libz 库的环境中构建。

$ pg_receivewal -D backup2/ --compress=9 &

2.10.pg_restore

• -N (–exclude-schema)

To specify the name of the schema not to be restored has been added.

• --no-subscriptions

Exclude SUBSCRIPTION objects used for Logical Replication

• --no-publications

Exclude PUBLICATION objects used for Logical Replication

2.11.pg_upgrade

在内部，它将表和序列视为单独的对象。

2.12.createuser

--unencrypted" option (-N option) has been deprecated.

2.13.createlang / droplang

createlang 命令、droplang 命令已弃用。

3.contrib 模块

本节描述了 contrib 模块的新功能。

3.1.postgres_fdw

• 聚合操作可以下推到源端

PostgreSQL 9.6

postgres=# explain analyze select count(*) from table2 ;
 QUERY PLAN                                      
----------------------------------------------------------------------------------
Aggregate (cost=220.92..220.93 rows=1 width=0) (actual  time=13778.312..13778.313 rows=1 
loops=1)->  Foreign Scan on table2 (cost=100.00..212.39 rows=3413 width=0) (actual 
time=2.424..13329.284 rows=1000000 loops=1)
 Planning time: 0.106 ms
 Execution time: 13780.712 ms。
(4 行记录)

PostgreSQL 10

 postgres=# explain analyze select count(*) from table2 ;
 QUERY PLAN                                            
-------------------------------------------------------------------------------------------------
Foreign Scan  (cost=108.53..152.69 rows=1 width=8) (actual time=112.222..112.225 rows=1 
loops=1)
 Relations: Aggregate on (public.table2)
 Planning time: 0.153 ms
 Execution time: 115.023 ms
 (4 行记录)

上述 SQL 语句在 FOREIGN SERVER 处转换为以下 SQL 语句。

参数设置为 log_statement = 'all'
statement: START TRANSACTION ISOLATION LEVEL REPEATABLE READ 
execute <unnamed>: DECLARE c1 CURSOR FOR 
select count(*) from table2 
statement: FETCH 100 FROM c1 
statement: CLOSE c1 
statement: COMMIT TRANSACTION

• FULL JOIN下推源端

postgres=> CREATE FOREIGN TABLE remote_employees (
    id INT,
    name VARCHAR(100),
    salary NUMERIC
)
  SERVER remote_server
  OPTIONS (schema_name 'public', table_name 'employees');

postgres=> CREATE FOREIGN TABLE remote_employees1 (
    id INT,
    name VARCHAR(100),
    salary NUMERIC
)
  SERVER remote_server
  OPTIONS (schema_name 'public', table_name 'employees1');

postgres=> select * from remote_employees1;
 id |    name     | salary 
----+-------------+--------
  1 | John Doe    |  55000
  2 | Jane Smith  |  60000
  3 | Alice Brown |  48000
(3 rows)
postgres=> select * from remote_employees;
 id |    name     | salary 
----+-------------+--------
  1 | John Doe    |  55000
  2 | Jane Smith  |  60000
  3 | Alice Brown |  48000
  4 | John Doe    |  55000
  5 | Jane Smith  |  60000
  6 | Alice Brown |  48000
  7 | John Doe    |  55000
  8 | Jane Smith  |  60000
  9 | Alice Brown |  48000
 10 | John Doe    |  55000
 11 | Jane Smith  |  60000
 12 | Alice Brown |  48000
(12 rows)


postgres=> explain (analyze,verbose) SELECT * FROM (SELECT * FROM remote_employees1 WHERE 
id < 3) r1 FULL JOIN (SELECT * FROM remote_employees WHERE id < 9) r2 ON (TRUE) LIMIT 10 ;
                                                                                                                           QUERY PLAN             
                                                                                                               
--------------------------------------------------------------------------------------------------------------------------------------------------

 Limit  (cost=100.00..100.23 rows=10 width=508) (actual time=1.398..1.400 rows=10 loops=1)
   Output: remote_employees1.id, remote_employees1.name, remote_employees1.salary, remote_employees.id, remote_employees.name, remote_employees.sa
lary
   ->  Foreign Scan  (cost=100.00..319.43 rows=9604 width=508) (actual time=1.397..1.398 rows=10 loops=1)
         Output: remote_employees1.id, remote_employees1.name, remote_employees1.salary, remote_employees.id, remote_employees.name, remote_employ
ees.salary
         Relations: (public.remote_employees1) FULL JOIN (public.remote_employees)
         Remote SQL: SELECT s4.c1, s4.c2, s4.c3, s5.c1, s5.c2, s5.c3 FROM ((SELECT id, name, salary FROM public.employees1 WHERE ((id < 3))) s4(c1
, c2, c3) FULL JOIN (SELECT id, name, salary FROM public.employees WHERE ((id < 9))) s5(c1, c2, c3) ON (TRUE))
 Planning time: 0.126 ms
 Execution time: 2.733 ms
(8 rows)

3.2.file_fdw

添加了用于运行应用程序的 “program” 选项。改为指定 program 选项的 filename 选项中指定文件名。当 FOREIGN TABLE 的 SELECT 语句执行时，将自动执行指定的程序。执行程序的内容标准输出的输出将作为元组返回给应用程序。

postgres=# echo 'echo "1,a"'>1.sh && chmod +x 1.sh
postgres=#  CREATE EXTENSION file_fdw ;
CREATE EXTENSION
postgres=#  CREATE SERVER fs FOREIGN DATA WRAPPER file_fdw ;
CREATE SERVER

--程序 1.sh 的执行结果可以返回到查询结果中
postgres=# CREATE FOREIGN TABLE tfile1 (id NUMERIC, val VARCHAR(10)) SERVER fs OPTIONS (program '/var/lib/postgresql/1.sh', delimiter ',') ;
CREATE FOREIGN TABLE
postgres=# 
postgres=# select * from tfile1;
 id | val 
----+-----
  1 | a
(1 row)

3.3.amcheck

用于检查 BTree 索引一致性的 amcheck 模块已添加到 contrib 中模块。此模块中添加了以下函数。

• bt_index_check （索引 regclass）

检查指定 BTree 索引的完整性

• bt_index_parent_check （索引 regclass）

检查父子索引的一致性
在下面的示例中，对索引 （idx1_check1） 执行 bt_index_check 函数，其中某些数据已损坏。

postgres=# CREATE EXTENSION amcheck ; 
CREATE EXTENSION 
postgres=# SELECT bt_index_check('idx1_check1') ; 
ERROR:  item order invariant violated for index "idx1_check1" 
DETAIL:  Lower index tid=(1,2) (points to heap tid=(0,2)) higher index 
tid=(1,3) (points to heap tid=(0,3)) page lsn=0/7EFE4638. 

3.4.pageinspect

新增了以下与 Hash Index 对应的函数。
• hash_page_type
• hash_page_stats
• hash_page_items
• hash_metapage_info
• page_checksum
• bt_page_items(IN page bytea)

postgres=# \d test_hash_table 
                                    Table "public.test_hash_table"
 Column |          Type          | Collation | Nullable |                   Default                   
--------+------------------------+-----------+----------+---------------------------------------------
 id     | integer                |           | not null | nextval('test_hash_table_id_seq'::regclass)
 name   | character varying(100) |           |          | 
Indexes:
    "test_hash_table_pkey" PRIMARY KEY, btree (id)
    "test_hash_index" hash (id)

postgres=# 
postgres=# select hash_page_type(get_raw_page('test_hash_index',0));
 hash_page_type 
----------------
 metapage
(1 row)
postgres=# select hash_page_type(get_raw_page('test_hash_index',1));
 hash_page_type 
----------------
 bucket
(1 row)

postgres=# select hash_page_type(get_raw_page('test_hash_index',2));
 hash_page_type 
----------------
 bucket
(1 row)

postgres=# select hash_page_type(get_raw_page('test_hash_index',3));
 hash_page_type 
----------------
 bitmap
(1 row)

postgres=# select live_items, dead_items from hash_page_stats(get_raw_page('test_hash_index',1));
 live_items | dead_items 
------------+------------
          3 |          0
(1 row)
postgres=# select * from hash_page_items(get_raw_page('test_hash_index',0));
ERROR:  page is not a hash bucket or overflow page
postgres=# select * from hash_page_items(get_raw_page('test_hash_index',1));
 itemoffset | ctid  |    data    
------------+-------+------------
          1 | (0,2) | 1134484726
          2 | (0,1) | 2389907270
          3 | (0,5) | 2964702588
(3 rows)

postgres=# select * from hash_page_items(get_raw_page('test_hash_index',2));
 itemoffset | ctid  |    data    
------------+-------+------------
          1 | (0,4) | 3283889963
          2 | (0,3) | 4266872727
(2 rows)

postgres=# select * from hash_page_items(get_raw_page('test_hash_index',3));
ERROR:  page is not a hash bucket or overflow page

3.5.pgstattuple

• pgstathashindex
提供有关 Hash Index 的信息

postgres=# create extension pgstattuple;
CREATE EXTENSION
postgres=# 
postgres=#  SELECT * FROM pgstathashindex('test_hash_index') ;
 version | bucket_pages | overflow_pages | bitmap_pages | unused_pages | live_items | dead_items |   free_percent   
---------+--------------+----------------+--------------+--------------+------------+------------+------------------
       4 |            2 |              0 |            1 |            0 |          5 |          0 | 99.3866535819431
(1 row)

3.6.btree_gist / btree_gin

现在可以在 UUID 类型列和 ENUM 类型列中创建 GiST 索引。GIN 索引可以在 ENUM 类型的列中创建。

postgres=# CREATE EXTENSION btree_gist ;
CREATE EXTENSION
postgres=# CREATE TYPE type1 AS ENUM ('typ1', 'typ2', 'typ3') ;
CREATE TYPE
postgres=# CREATE TABLE gist1(c1 UUID, c2 type1) ;
CREATE TABLE
postgres=# CREATE INDEX idx1_gist1 ON gist1 USING gist (c1) ;
CREATE INDEX
postgres=# CREATE INDEX idx2_gist1 ON gist1 USING gist (c2) ;
CREATE INDEX
postgres=# select * from gist1;
 c1 | c2 
----+----
(0 rows)

postgres=# -- 插入示例数据
postgres=# INSERT INTO gist1 (c1, c2) VALUES
postgres-#   ('a0eeb238-d3c8-11eb-b8bc-0242ac130003', 'typ1'),
postgres-#   ('b1eeed59-d3c8-11eb-b8bc-0242ac130003', 'typ2'),
postgres-#   ('c2eeed59-d3c8-11eb-b8bc-0242ac130003', 'typ3');
INSERT 0 3
postgres=# SELECT * FROM gist1;
                  c1                  |  c2  
--------------------------------------+------
 a0eeb238-d3c8-11eb-b8bc-0242ac130003 | typ1
 b1eeed59-d3c8-11eb-b8bc-0242ac130003 | typ2
 c2eeed59-d3c8-11eb-b8bc-0242ac130003 | typ3
(3 rows)

3.7.pg_stat_statements

SQL 语句存储在 pg_stat_statements 视图中的格式已经发生了变化。之前，WHERE 子句中的字面值通常以问号（?）的形式输出，但现在已被更改为 ${N} 的格式（其中 N = 1, 2, …）

postgres=# create extension pg_stat_statements;
CREATE EXTENSION
postgres=# select queryid,query from pg_stat_statements limit 2;
  queryid   |                   query                   
------------+-------------------------------------------
  287764235 | drop extension pg_stat_statements
 1675270703 | select * from pg_stat_statements limit $1
(2 rows)

3.7.tsearch2

tsearch2 模块已删除。

参考

《PostgreSQL_10_New_Features_en_20170522-1》
《快速掌握PostgreSQL版本新特性》