On Tue, Jan 9, 2018 at 3:53 AM, Rambabu V <ram.wis...@gmail.com> wrote:

> Hi Team,
>
> Daily 4000 Archive files are generating and these are occupying more
> space, we are trying to compress wall files with using wal_compression
> parameter, but we are not seeing any change in wal files count, could you
> please help us on this.
>

That's very little information to go on.

You'll probably want to inspect WAL record stats before and after enabling
wal_compression to see whether it makes sense to do so. Take a look at
pg_xlogdump --stats

For example:

$ pg_xlogdump --stats -p /path/to/pg_xlog 000000010002C364000000F0
000000010002C364000000FA
Type                                           N      (%)          Record
size      (%)             FPI size      (%)        Combined size      (%)
----                                           -      ---
-----------      ---             --------      ---
-------------      ---
XLOG                                           0 (
0.00)                    0 (  0.00)                    0 (
0.00)                    0 (  0.00)
Transaction                                   11 (  0.00)
352 (  0.00)                    0 (  0.00)                  352 (  0.00)
Storage                                        0 (
0.00)                    0 (  0.00)                    0 (
0.00)                    0 (  0.00)
CLOG                                           0 (
0.00)                    0 (  0.00)                    0 (
0.00)                    0 (  0.00)
Database                                       0 (
0.00)                    0 (  0.00)                    0 (
0.00)                    0 (  0.00)
Tablespace                                     0 (
0.00)                    0 (  0.00)                    0 (
0.00)                    0 (  0.00)
MultiXact                                      4 (  0.00)
208 (  0.00)                    0 (  0.00)                  208 (  0.00)
RelMap                                         0 (
0.00)                    0 (  0.00)                    0 (
0.00)                    0 (  0.00)
Standby                                        2 (  0.00)
116 (  0.00)                    0 (  0.00)                  116 (  0.00)
Heap2                                       2504 (  0.18)
78468 (  0.20)              1385576 (  3.55)              1464044 (  1.89)
Heap                                      667619 ( 48.23)
19432159 ( 50.47)             28641357 ( 73.35)             48073516 (
61.99)
Btree                                     712093 ( 51.45)
18643846 ( 48.42)              9021270 ( 23.10)             27665116 (
35.67)
Hash                                           0 (
0.00)                    0 (  0.00)                    0 (
0.00)                    0 (  0.00)
Gin                                            0 (
0.00)                    0 (  0.00)                    0 (
0.00)                    0 (  0.00)
Gist                                           0 (
0.00)                    0 (  0.00)                    0 (
0.00)                    0 (  0.00)
Sequence                                    1918 (  0.14)
349076 (  0.91)                    0 (  0.00)               349076 (  0.45)
SPGist                                         0 (
0.00)                    0 (  0.00)                    0 (
0.00)                    0 (  0.00)
BRIN                                           0 (
0.00)                    0 (  0.00)                    0 (
0.00)                    0 (  0.00)
CommitTs                                       0 (
0.00)                    0 (  0.00)                    0 (
0.00)                    0 (  0.00)
ReplicationOrigin                              0 (
0.00)                    0 (  0.00)                    0 (
0.00)                    0 (  0.00)
                                        --------
--------                      --------                      --------
Total                                    1384151
38504225 [49.65%]             39048203 [50.35%]             77552428 [100%]


That shows 50% of that are full page writes. This is with compression
enabled. WAL compression will only help FPW, so if you don't have a large
volume of FPW, or they don't compress well, you won't benefit much.

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