转载：https://yq.aliyun.com/articles/190
Greenplum支持表空间，创建表空间时，需要指定filespace。
postgres=# \h create tablespace;
Command: CREATE TABLESPACE
Description: define a new tablespace
Syntax:
CREATE TABLESPACE tablespace_name [OWNER username] FILESPACE filespace_name
那么什么是filespace呢？
GP在初始化完后，有一个默认的filespace ： pg_system。
表空间pg_default和pg_global都放在这个filespace下面。
也就是说一个filespace可以被多个表空间使用。
postgres=# select oid,* from pg_filespace;
oid | fsname | fsowner
------+-----------+---------
3052 | pg_system | 10
(1 row)
postgres=# select * from pg_tablespace;
spcname | spcowner | spclocation | spcacl | spcprilocations | spcmirlocations | spcfsoid
------------+----------+-------------+--------+-----------------+-----------------+----------
pg_default | 10 | | | | | 3052
pg_global | 10 | | | | | 3052
(2 rows)
还有TEMPORARY_FILES和TRANSACTION_FILES对应的filespace如下：
$gpfilespace --showtempfilespace
20151218:16:02:07:063949 gpfilespace:127.0.0.1:digoal-[INFO]:-
A tablespace requires a file system location to store its database
files. A filespace is a collection of file system locations for all components
in a Greenplum system (primary segment, mirror segment and master instances).
Once a filespace is created, it can be used by one or more tablespaces.
20151218:16:02:07:063949 gpfilespace:127.0.0.1:digoal-[INFO]:-Getting filespace information for TEMPORARY_FILES
20151218:16:02:08:063949 gpfilespace:127.0.0.1:digoal-[INFO]:-Checking for filespace consistency
20151218:16:02:08:063949 gpfilespace:127.0.0.1:digoal-[INFO]:-Obtaining current filespace entries used by TEMPORARY_FILES
20151218:16:02:09:063949 gpfilespace:127.0.0.1:digoal-[INFO]:-TEMPORARY_FILES OIDs are consistent for pg_system filespace
20151218:16:02:11:063949 gpfilespace:127.0.0.1:digoal-[INFO]:-TEMPORARY_FILES entries are consistent for pg_system filespace
20151218:16:02:11:063949 gpfilespace:127.0.0.1:digoal-[INFO]:-Obtaining current filespace entries used by TEMPORARY_FILES
20151218:16:02:11:063949 gpfilespace:127.0.0.1:digoal-[INFO]:-Current Filespace for TEMPORARY_FILES is pg_system
20151218:16:02:11:063949 gpfilespace:127.0.0.1:digoal-[INFO]:-1 /disk1/digoal/gpdata/gpseg-1
20151218:16:02:11:063949 gpfilespace:127.0.0.1:digoal-[INFO]:-25 /disk1/digoal/gpdata_mirror/gpseg0
20151218:16:02:11:063949 gpfilespace:127.0.0.1:digoal-[INFO]:-2 /disk1/digoal/gpdata/gpseg0
......
$gpfilespace --showtransfilespace
20151218:16:09:41:071104 gpfilespace:127.0.0.1:digoal-[INFO]:-
A tablespace requires a file system location to store its database
files. A filespace is a collection of file system locations for all components
in a Greenplum system (primary segment, mirror segment and master instances).
Once a filespace is created, it can be used by one or more tablespaces.
20151218:16:09:41:071104 gpfilespace:127.0.0.1:digoal-[INFO]:-Getting filespace information for TRANSACTION_FILES
20151218:16:09:41:071104 gpfilespace:127.0.0.1:digoal-[INFO]:-Checking for filespace consistency
20151218:16:09:41:071104 gpfilespace:127.0.0.1:digoal-[INFO]:-Obtaining current filespace entries used by TRANSACTION_FILES
20151218:16:09:42:071104 gpfilespace:127.0.0.1:digoal-[INFO]:-TRANSACTION_FILES OIDs are consistent for pg_system filespace
20151218:16:09:44:071104 gpfilespace:127.0.0.1:digoal-[INFO]:-TRANSACTION_FILES entries are consistent for pg_system filespace
20151218:16:09:44:071104 gpfilespace:127.0.0.1:digoal-[INFO]:-Obtaining current filespace entries used by TRANSACTION_FILES
20151218:16:09:44:071104 gpfilespace:127.0.0.1:digoal-[INFO]:-Current Filespace for TRANSACTION_FILES is pg_system
20151218:16:09:44:071104 gpfilespace:127.0.0.1:digoal-[INFO]:-1 /disk1/digoal/gpdata/gpseg-1
20151218:16:09:44:071104 gpfilespace:127.0.0.1:digoal-[INFO]:-25 /disk1/digoal/gpdata_mirror/gpseg0
20151218:16:09:44:071104 gpfilespace:127.0.0.1:digoal-[INFO]:-2 /disk1/digoal/gpdata/gpseg0
20151218:16:09:44:071104 gpfilespace:127.0.0.1:digoal-[INFO]:-26 /disk1/digoal/gpdata_mirror/gpseg1
......
如果我们的greenplum集群中，有SSD硬盘，又有SATA硬盘。怎样更好的利用这些空间呢？
方法1.
用flashcache或bcache，通过device mapper技术，将SSD和SATA绑定，做成块设备。
再通过 逻辑卷管理 或者 软RAID 或者 brtfs or zfs管理起来，做成大的文件系统。
（还有一种方法是用RHEL 7提供的LVM，可以将SSD作为二级缓存）
这种方法对GP来说，是混合动力，可以创建一个或多个文件系统（都具备混合动力）。
所以建议只需要一个pg_system filespace就够了(除非容量到了文件系统管理的极限，那样的话可以分成多个文件系统)。
用多个文件系统的情况下，就需要对每个文件系统，创建对应的目录，以及filespace。
方法2.
SSD和SATA分开，各自创建各自的文件系统。
对每个文件系统，创建对应的目录，以及filespace。
创建filespace非常简单，分几步。
如下：
1. 创建目录，需要在所有的角色对应的主机中创建。给予gp 操作系统管理用户对应的权限。
master
$ mkdir /ssd1/gpdata/master_p
$ chown gpadmin:gpadmin /ssd1/gpdata/master_p
master standby
$ mkdir /ssd1/gpdata/master_s
$ chown gpadmin:gpadmin /ssd1/gpdata/master_s
segment
$ mkdir /ssd1/gpdata_p
$ chown gpadmin:gpadmin /ssd1/gpdata_p
segment mirror
$ mkdir /ssd1/gpdata_s
$ chown gpadmin:gpadmin /ssd1/gpdata_s
2. 查看系统配置
postgres=# select dbid,content,role,preferred_role,hostname,port from gp_segment_configuration order by role,dbid;
dbid | content | role | preferred_role | hostname | port
------+---------+------+----------------+-------------------+-------
2 | 0 | m | p | digoal.sqa.zmf | 40000
3 | 1 | m | p | digoal.sqa.zmf | 40001
4 | 2 | m | p | digoal.sqa.zmf | 40002
5 | 3 | m | p | digoal.sqa.zmf | 40003
6 | 4 | m | p | digoal.sqa.zmf | 40004
7 | 5 | m | p | digoal.sqa.zmf | 40005
8 | 6 | m | p | digoal.sqa.zmf | 40006
9 | 7 | m | p | digoal.sqa.zmf | 40007
10 | 8 | m | p | digoal.sqa.zmf | 40008
11 | 9 | m | p | digoal.sqa.zmf | 40009
12 | 10 | m | p | digoal.sqa.zmf | 40010
13 | 11 | m | p | digoal.sqa.zmf | 40011
14 | 12 | m | p | digoal.sqa.zmf | 40012
15 | 13 | m | p | digoal.sqa.zmf | 40013
16 | 14 | m | p | digoal.sqa.zmf | 40014
17 | 15 | m | p | digoal.sqa.zmf | 40015
18 | 16 | m | p | digoal.sqa.zmf | 40016
19 | 17 | m | p | digoal.sqa.zmf | 40017
20 | 18 | m | p | digoal.sqa.zmf | 40018
21 | 19 | m | p | digoal.sqa.zmf | 40019
22 | 20 | m | p | digoal.sqa.zmf | 40020
23 | 21 | m | p | digoal.sqa.zmf | 40021
24 | 22 | m | p | digoal.sqa.zmf | 50011
1 | -1 | p | p | digoal.sqa.zmf | 1921
25 | 0 | p | m | digoal.sqa.zmf | 41000
26 | 1 | p | m | digoal.sqa.zmf | 41001
27 | 2 | p | m | digoal.sqa.zmf | 41002
28 | 3 | p | m | digoal.sqa.zmf | 41003
29 | 4 | p | m | digoal.sqa.zmf | 41004
30 | 5 | p | m | digoal.sqa.zmf | 41005
31 | 6 | p | m | digoal.sqa.zmf | 41006
32 | 7 | p | m | digoal.sqa.zmf | 41007
33 | 8 | p | m | digoal.sqa.zmf | 41008
34 | 9 | p | m | digoal.sqa.zmf | 41009
35 | 10 | p | m | digoal.sqa.zmf | 41010
36 | 11 | p | m | digoal.sqa.zmf | 41011
37 | 12 | p | m | digoal.sqa.zmf | 41012
38 | 13 | p | m | digoal.sqa.zmf | 41013
39 | 14 | p | m | digoal.sqa.zmf | 41014
40 | 15 | p | m | digoal.sqa.zmf | 41015
41 | 16 | p | m | digoal.sqa.zmf | 41016
42 | 17 | p | m | digoal.sqa.zmf | 41017
43 | 18 | p | m | digoal.sqa.zmf | 41018
44 | 19 | p | m | digoal.sqa.zmf | 41019
45 | 20 | p | m | digoal.sqa.zmf | 41020
46 | 21 | p | m | digoal.sqa.zmf | 41021
47 | 22 | p | m | digoal.sqa.zmf | 41022
(47 rows)
3. 创建配置文件，格式如下，假如我要创建一个名为ssd1的filespace。
字段包含(hostname, dbid, DIR/$prefix + $content)
$ vi conf
filespace:ssd1
digoal.sqa.zmf:1:/ssd1/gpdata/master_p/gp-1
digoal.sqa.zmf:2:/ssd1/gpdata_p/gp0
digoal.sqa.zmf:3:/ssd1/gpdata_p/gp1
......
digoal.sqa.zmf:25:/ssd1/gpdata_s/gp0
digoal.sqa.zmf:26:/ssd1/gpdata_s/gp1
......
还有一种方法是使用gpfilespace -o conf来生成配置文件。(在提示时输入目录名DIR的部分即可)
4. 创建filespace
gpfilespace -c conf -h 127.0.0.1 -p 1921 -U digoal -W digoal
20151218:17:16:39:108364 gpfilespace:127.0.0.1:digoal-[INFO]:-Connecting to database
20151218:17:16:39:108364 gpfilespace:127.0.0.1:digoal-[INFO]:-Filespace "ssd1" successfully created
......
然后gpfilespace会自动在数据库执行以下DDL SQL。创建对应的filespace。
所以我们也可以自己在数据库中执行SQL来创建filespace。
CREATE FILESPACE ssd1
(
1: '/disk1/digoal/new_p/gp-1',
2: '/disk1/digoal/new_p/gp0',
3: '/disk1/digoal/new_p/gp1',
4: '/disk1/digoal/new_p/gp2',
5: '/disk1/digoal/new_p/gp3',
6: '/disk1/digoal/new_p/gp4',
7: '/disk1/digoal/new_p/gp5',
8: '/disk1/digoal/new_p/gp6',
9: '/disk1/digoal/new_p/gp7',
10: '/disk1/digoal/new_p/gp8',
11: '/disk1/digoal/new_p/gp9',
12: '/disk1/digoal/new_p/gp10',
13: '/disk1/digoal/new_p/gp11',
14: '/disk1/digoal/new_p/gp12',
15: '/disk1/digoal/new_p/gp13',
16: '/disk1/digoal/new_p/gp14',
17: '/disk1/digoal/new_p/gp15',
18: '/disk1/digoal/new_p/gp16',
19: '/disk1/digoal/new_p/gp17',
20: '/disk1/digoal/new_p/gp18',
21: '/disk1/digoal/new_p/gp19',
22: '/disk1/digoal/new_p/gp20',
23: '/disk1/digoal/new_p/gp21',
24: '/disk1/digoal/new_p/gp22',
25: '/disk1/digoal/new_s/gp0',
26: '/disk1/digoal/new_s/gp1',
27: '/disk1/digoal/new_s/gp2',
28: '/disk1/digoal/new_s/gp3',
29: '/disk1/digoal/new_s/gp4',
30: '/disk1/digoal/new_s/gp5',
31: '/disk1/digoal/new_s/gp6',
32: '/disk1/digoal/new_s/gp7',
33: '/disk1/digoal/new_s/gp8',
34: '/disk1/digoal/new_s/gp9',
35: '/disk1/digoal/new_s/gp10',
36: '/disk1/digoal/new_s/gp11',
37: '/disk1/digoal/new_s/gp12',
38: '/disk1/digoal/new_s/gp13',
39: '/disk1/digoal/new_s/gp14',
40: '/disk1/digoal/new_s/gp15',
41: '/disk1/digoal/new_s/gp16',
42: '/disk1/digoal/new_s/gp17',
43: '/disk1/digoal/new_s/gp18',
44: '/disk1/digoal/new_s/gp19',
45: '/disk1/digoal/new_s/gp20',
46: '/disk1/digoal/new_s/gp21',
47: '/disk1/digoal/new_s/gp22'
);
现在你可以使用这个filespace了.
例如
1. 将temp , trans移动到这个新的filespace.
$gpfilespace --movetempfilespace ssd1
20151218:17:17:29:008363 gpfilespace:127.0.0.1:digoal-[INFO]:-
A tablespace requires a file system location to store its database
files. A filespace is a collection of file system locations for all components
in a Greenplum system (primary segment, mirror segment and master instances).
Once a filespace is created, it can be used by one or more tablespaces.
20151218:17:17:29:008363 gpfilespace:127.0.0.1:digoal-[INFO]:-Database was started in NORMAL mode
20151218:17:17:29:008363 gpfilespace:127.0.0.1:digoal-[INFO]:-Stopping Greenplum Database
20151218:17:17:57:008363 gpfilespace:127.0.0.1:digoal-[INFO]:-Starting Greenplum Database in master only mode
20151218:17:18:02:008363 gpfilespace:127.0.0.1:digoal-[INFO]:-Checking if filespace ssd1 exists
20151218:17:18:02:008363 gpfilespace:127.0.0.1:digoal-[INFO]:-Checking if filespace is same as current filespace
20151218:17:18:02:008363 gpfilespace:127.0.0.1:digoal-[INFO]:-Stopping Greenplum Database in master only mode
20151218:17:18:04:008363 gpfilespace:127.0.0.1:digoal-[INFO]:-Checking for connectivity
20151218:17:18:04:008363 gpfilespace:127.0.0.1:digoal-[INFO]:-Obtaining current filespace information
20151218:17:18:04:008363 gpfilespace:127.0.0.1:digoal-[INFO]:-Obtaining current filespace entries used by TEMPORARY_FILES
20151218:17:18:04:008363 gpfilespace:127.0.0.1:digoal-[INFO]:-Obtaining segment information ...
20151218:17:18:04:008363 gpfilespace:127.0.0.1:digoal-[INFO]:-Creating RemoteOperations list
20151218:17:18:04:008363 gpfilespace:127.0.0.1:digoal-[INFO]:-Moving TEMPORARY_FILES filespace from pg_system to ssd1 ...
20151218:17:18:06:008363 gpfilespace:127.0.0.1:digoal-[INFO]:-Starting Greenplum Database
$gpfilespace --movetransfilespace ssd1
...
20151218:17:19:17:055389 gpfilespace:127.0.0.1:digoal-[INFO]:-Moving TRANSACTION_FILES filespace from pg_system to ssd1 ...
20151218:17:21:16:055389 gpfilespace:127.0.0.1:digoal-[INFO]:-Starting Greenplum Database
2. 创建表空间，使用这个filespace.
postgres=# create tablespace tbs_ssd1 filespace ssd1;
CREATE TABLESPACE
postgres=# create table tt(id int) tablespace tbs_ssd1;
NOTICE: Table doesn't have 'DISTRIBUTED BY' clause -- Using column named 'id' as the Greenplum Database data distribution key for this table.
HINT: The 'DISTRIBUTED BY' clause determines the distribution of data. Make sure column(s) chosen are the optimal data distribution key to minimize skew.
CREATE TABLE
postgres=# select * from pg_tablespace ;
spcname | spcowner | spclocation | spcacl | spcprilocations | spcmirlocations | spcfsoid
------------+----------+-------------+--------+-----------------+-----------------+----------
pg_default | 10 | | | | | 3052
pg_global | 10 | | | | | 3052
tbs_ssd1 | 10 | | | | | 69681
(3 rows)
postgres=# select * from pg_filespace;
fsname | fsowner
-----------+---------
pg_system | 10
ssd1 | 10
(2 rows)
greenplum为什么会引入filespace的概念？
因为主机目录结构可能不一样，所以原有的目录结构式的方法来创建表空间，可能不够灵活。
最后，如何查看每个节点的filespace和location的关系？
digoal=# select a.dbid,a.content,a.role,a.port,a.hostname,b.fsname,c.fselocation from gp_segment_configuration a,pg_filespace b,pg_filespace_entry c where a.dbid=c.fsedbid and b.oid=c.fsefsoid order by content;
dbid | content | role | port | hostname | fsname | fselocation
------+---------+------+-------+-------------------+-----------+--------------------------------------
1 | -1 | p | 1921 | digoal193096.zmf | pg_system | /data01/gpdata/master_pgdata/gpseg-1
2 | 0 | p | 40000 | digoal193096.zmf | pg_system | /data01/gpdata/gpseg0
3 | 1 | p | 40001 | digoal193096.zmf | pg_system | /data01/gpdata/gpseg1
4 | 2 | p | 40002 | digoal193096.zmf | pg_system | /data01/gpdata/gpseg2
5 | 3 | p | 40000 | digoal199092.zmf | pg_system | /data01/gpdata/gpseg3
6 | 4 | p | 40001 | digoal199092.zmf | pg_system | /data01/gpdata/gpseg4
7 | 5 | p | 40002 | digoal199092.zmf | pg_system | /data01/gpdata/gpseg5
8 | 6 | p | 40000 | digoal200164.zmf | pg_system | /data01/gpdata/gpseg6
9 | 7 | p | 40001 | digoal200164.zmf | pg_system | /data01/gpdata/gpseg7
10 | 8 | p | 40002 | digoal200164.zmf | pg_system | /data01/gpdata/gpseg8
11 | 9 | p | 40000 | digoal204016.zmf | pg_system | /data01/gpdata/gpseg9
12 | 10 | p | 40001 | digoal204016.zmf | pg_system | /data01/gpdata/gpseg10
13 | 11 | p | 40002 | digoal204016.zmf | pg_system | /data01/gpdata/gpseg11
14 | 12 | p | 40000 | digoal204063.zmf | pg_system | /data01/gpdata/gpseg12
15 | 13 | p | 40001 | digoal204063.zmf | pg_system | /data01/gpdata/gpseg13
16 | 14 | p | 40002 | digoal204063.zmf | pg_system | /data01/gpdata/gpseg14
17 | 15 | p | 40003 | digoal193096.zmf | pg_system | /data01/gpdata/gpseg15
18 | 16 | p | 40003 | digoal199092.zmf | pg_system | /data01/gpdata/gpseg16
19 | 17 | p | 40003 | digoal200164.zmf | pg_system | /data01/gpdata/gpseg17
20 | 18 | p | 40003 | digoal204016.zmf | pg_system | /data01/gpdata/gpseg18
21 | 19 | p | 40003 | digoal204063.zmf | pg_system | /data01/gpdata/gpseg19
22 | 20 | p | 40000 | digoal209198.zmf | pg_system | /data01/gpdata/gpseg22
23 | 21 | p | 40001 | digoal209198.zmf | pg_system | /data01/gpdata/gpseg23
24 | 22 | p | 40002 | digoal209198.zmf | pg_system | /data01/gpdata/gpseg24
25 | 23 | p | 40003 | digoal209198.zmf | pg_system | /data01/gpdata/gpseg25
(25 rows)
[参考]
gpfilespace -h