Thread: Observation on integer types documentation

Observation on integer types documentation

From

Dan McGee

Date:

30 April 2012, 22:22:10

Hey everyone,

Reading the docs today, I came across this paragraph
(http://www.postgresql.org/docs/devel/static/datatype-numeric.html#DATATYPE-INT),
which goes back several major versions:

> The type integer is the common choice, as it offers the best balance between range, storage size, and performance.
Thesmallint type is generally only used if disk space is at a premium. The bigint type should only be used if the range
ofthe integer type is insufficient, because the latter is definitely faster. 

A few thoughts on this.
1) the use of the word "latter" isn't totally clear, or at least I had
to re-read it to realize former was 'bigint' and latter was 'integer'.
It might just be the style of writing.
2) I'm less than convinced this note belongs in modern documentation,
and set out to test that theory. My full results are below, but the
summary is this: on a 64-bit system, there seems to be only a minimal
measurable performance difference (< 5%) and very little size
difference. In the case of the indexes, the size difference is zero.
This is not true for a 32-bit system (where it is 39% slower), but the
blanket statement doesn't hold true, which is why I'm writing all this
up.

On a final note, the following paragraph also seems like it has
outlived its useful life:

> On very minimal operating systems the bigint type might not function correctly, because it relies on compiler support
foreight-byte integers. On such machines, bigint acts the same as integer, but still takes up eight bytes of storage.
(Weare not aware of any modern platform where this is the case.) 

Thanks!
-Dan


Table setup (only difference is type of 'id' column):

Table "public.package_files"
    Column    |          Type          |       Modifiers
--------------+------------------------+------------------------
 id           | integer                | not null
 pkg_id       | integer                | not null
 is_directory | boolean                | not null default false
 directory    | character varying(255) | not null
 filename     | character varying(255) |
Indexes:
    "package_files_pkey" PRIMARY KEY, btree (id)
    "package_files_pkg_id" btree (pkg_id) CLUSTER


Table "public.package_files_int8"
    Column    |          Type          |       Modifiers
--------------+------------------------+------------------------
 id           | bigint                 | not null
 pkg_id       | integer                | not null
 is_directory | boolean                | not null default false
 directory    | character varying(255) | not null
 filename     | character varying(255) |
Indexes:
    "package_files_int8_pkey" PRIMARY KEY, btree (id)
    "package_files_int8_pkg_id" btree (pkg_id) CLUSTER


# select count(*) from package_files;
 2621418
# select count(*) from package_files_int8 ;
 2621418


All runs below were done after issuing a few warm up queries, and both
tables went through a VACUUM/CLUSTER/ANALYZE sequence.

32-bit P4 2.4 GHz (single core). no enabled CPU frequency scaling, 1GB
total ram, shared_buffers 128MB, work_mem 4MB:

             relation             |    size
----------------------------------+------------
 public.package_files_int8        | 239 MB
 public.package_files             | 229 MB
 public.package_files_int8_pkey   | 56 MB
 public.package_files_int8_pkg_id | 45 MB
 public.package_files_pkey        | 45 MB
 public.package_files_pkg_id      | 45 MB

archweb=> \timing on
Timing is on.
archweb=> \t
Showing only tuples.
archweb=> select count(*) from (select * from package_files where
pkg_id in (48024, 48025, 40343) order by id) a;
 119325
Time: 516.558 ms
archweb=> select count(*) from (select * from package_files where
pkg_id in (48024, 48025, 40343) order by id) a;
 119325
Time: 519.720 ms
archweb=> select count(*) from (select * from package_files where
pkg_id in (48024, 48025, 40343) order by id) a;
 119325
Time: 533.330 ms
archweb=> select count(*) from (select * from package_files where
pkg_id in (48024, 48025, 40343) order by id) a;
 119325
Time: 519.095 ms
archweb=> select count(*) from (select * from package_files where
pkg_id in (48024, 48025, 40343) order by id) a;
 119325
Time: 520.253 ms

archweb=> select count(*) from (select * from package_files_int8 where
pkg_id in (48024, 48025, 40343) order by id) a;
 119325
Time: 731.194 ms
archweb=> select count(*) from (select * from package_files_int8 where
pkg_id in (48024, 48025, 40343) order by id) a;
 119325
Time: 730.329 ms
archweb=> select count(*) from (select * from package_files_int8 where
pkg_id in (48024, 48025, 40343) order by id) a;
 119325
Time: 724.646 ms
archweb=> select count(*) from (select * from package_files_int8 where
pkg_id in (48024, 48025, 40343) order by id) a;
 119325
Time: 710.815 ms
archweb=> select count(*) from (select * from package_files_int8 where
pkg_id in (48024, 48025, 40343) order by id) a;
 119325
Time: 724.519 ms




64-bit Core2 Quad 2.66 GHz (four core), CPU freq scaling disabled
(performance governor used), 8GB total ram, shared_buffers 128MB,
work_mem 4MB:

             relation             |    size
----------------------------------+------------
 public.package_files_int8        | 245 MB
 public.package_files             | 234 MB
 public.package_files_int8_pkey   | 56 MB
 public.package_files_pkg_id      | 56 MB
 public.package_files_int8_pkg_id | 56 MB
 public.package_files_pkey        | 56 MB

dmcgee=# select count(*) from (select * from package_files where
pkg_id in (48024, 48025, 40343) order by id) a;
 119325
Time: 177.078 ms
dmcgee=# select count(*) from (select * from package_files where
pkg_id in (48024, 48025, 40343) order by id) a;
 119325
Time: 176.109 ms
dmcgee=# select count(*) from (select * from package_files where
pkg_id in (48024, 48025, 40343) order by id) a;
 119325
Time: 177.478 ms
dmcgee=# select count(*) from (select * from package_files where
pkg_id in (48024, 48025, 40343) order by id) a;
 119325
Time: 176.639 ms
dmcgee=# select count(*) from (select * from package_files where
pkg_id in (48024, 48025, 40343) order by id) a;
 119325
Time: 176.453 ms

dmcgee=# select count(*) from (select * from package_files_int8 where
pkg_id in (48024, 48025, 40343) order by id) a;
 119325
Time: 185.768 ms
dmcgee=# select count(*) from (select * from package_files_int8 where
pkg_id in (48024, 48025, 40343) order by id) a;
 119325
Time: 185.159 ms
dmcgee=# select count(*) from (select * from package_files_int8 where
pkg_id in (48024, 48025, 40343) order by id) a;
 119325
Time: 184.407 ms
dmcgee=# select count(*) from (select * from package_files_int8 where
pkg_id in (48024, 48025, 40343) order by id) a;
 119325
Time: 184.555 ms
dmcgee=# select count(*) from (select * from package_files_int8 where
pkg_id in (48024, 48025, 40343) order by id) a;
 119325
Time: 184.290 ms


Overall results:

                       i686                            x86_64
                int4            int8            int4            int8
                516.558         731.194         177.078         185.768
                519.72          730.329         176.109         185.159
                533.33          724.646         177.478         184.407
                519.095         710.815         176.639         184.555
                520.253         724.519         176.453         184.29



Average         521.7912        724.3006        176.7514        184.8358
Stddev          6.6040841681    8.1530512264    0.5359499044    0.619288059
Ratio                   1.3881042839                    1.0457388173

Re: Observation on integer types documentation

From

Marcelo Sena

Date:

14 May 2012, 00:09:36

I'm new here but your proposal makes sense to me. Are the query plans equal on both architectures?

--
Marcelo Lacerda

On Mon, Apr 30, 2012 at 5:59 PM, Dan McGee <dpmcgee@gmail.com> wrote:

Hey everyone,

Reading the docs today, I came across this paragraph
(http://www.postgresql.org/docs/devel/static/datatype-numeric.html#DATATYPE-INT),
which goes back several major versions:

> The type integer is the common choice, as it offers the best balance between range, storage size, and performance. The smallint type is generally only used if disk space is at a premium. The bigint type should only be used if the range of the integer type is insufficient, because the latter is definitely faster.

A few thoughts on this.
1) the use of the word "latter" isn't totally clear, or at least I had
to re-read it to realize former was 'bigint' and latter was 'integer'.
It might just be the style of writing.
2) I'm less than convinced this note belongs in modern documentation,
and set out to test that theory. My full results are below, but the
summary is this: on a 64-bit system, there seems to be only a minimal
measurable performance difference (< 5%) and very little size
difference. In the case of the indexes, the size difference is zero.
This is not true for a 32-bit system (where it is 39% slower), but the
blanket statement doesn't hold true, which is why I'm writing all this
up.

On a final note, the following paragraph also seems like it has
outlived its useful life:

> On very minimal operating systems the bigint type might not function correctly, because it relies on compiler support for eight-byte integers. On such machines, bigint acts the same as integer, but still takes up eight bytes of storage. (We are not aware of any modern platform where this is the case.)

Thanks!
-Dan

Table setup (only difference is type of 'id' column):

Table "public.package_files"
Column | Type | Modifiers
--------------+------------------------+------------------------
id | integer | not null
pkg_id | integer | not null
is_directory | boolean | not null default false
directory | character varying(255) | not null
filename | character varying(255) |
Indexes:
"package_files_pkey" PRIMARY KEY, btree (id)
"package_files_pkg_id" btree (pkg_id) CLUSTER

Table "public.package_files_int8"
Column | Type | Modifiers
--------------+------------------------+------------------------
id | bigint | not null
pkg_id | integer | not null
is_directory | boolean | not null default false
directory | character varying(255) | not null
filename | character varying(255) |
Indexes:
"package_files_int8_pkey" PRIMARY KEY, btree (id)
"package_files_int8_pkg_id" btree (pkg_id) CLUSTER

# select count(*) from package_files;
2621418
# select count(*) from package_files_int8 ;
2621418

All runs below were done after issuing a few warm up queries, and both
tables went through a VACUUM/CLUSTER/ANALYZE sequence.

32-bit P4 2.4 GHz (single core). no enabled CPU frequency scaling, 1GB
total ram, shared_buffers 128MB, work_mem 4MB:

relation | size
----------------------------------+------------
public.package_files_int8 | 239 MB
public.package_files | 229 MB
public.package_files_int8_pkey | 56 MB
public.package_files_int8_pkg_id | 45 MB
public.package_files_pkey | 45 MB
public.package_files_pkg_id | 45 MB

archweb=> \timing on
Timing is on.
archweb=> \t
Showing only tuples.
archweb=> select count(*) from (select * from package_files where
pkg_id in (48024, 48025, 40343) order by id) a;
119325
Time: 516.558 ms
archweb=> select count(*) from (select * from package_files where
pkg_id in (48024, 48025, 40343) order by id) a;
119325
Time: 519.720 ms
archweb=> select count(*) from (select * from package_files where
pkg_id in (48024, 48025, 40343) order by id) a;
119325
Time: 533.330 ms
archweb=> select count(*) from (select * from package_files where
pkg_id in (48024, 48025, 40343) order by id) a;
119325
Time: 519.095 ms
archweb=> select count(*) from (select * from package_files where
pkg_id in (48024, 48025, 40343) order by id) a;
119325
Time: 520.253 ms

archweb=> select count(*) from (select * from package_files_int8 where
pkg_id in (48024, 48025, 40343) order by id) a;
119325
Time: 731.194 ms
archweb=> select count(*) from (select * from package_files_int8 where
pkg_id in (48024, 48025, 40343) order by id) a;
119325
Time: 730.329 ms
archweb=> select count(*) from (select * from package_files_int8 where
pkg_id in (48024, 48025, 40343) order by id) a;
119325
Time: 724.646 ms
archweb=> select count(*) from (select * from package_files_int8 where
pkg_id in (48024, 48025, 40343) order by id) a;
119325
Time: 710.815 ms
archweb=> select count(*) from (select * from package_files_int8 where
pkg_id in (48024, 48025, 40343) order by id) a;
119325
Time: 724.519 ms

64-bit Core2 Quad 2.66 GHz (four core), CPU freq scaling disabled
(performance governor used), 8GB total ram, shared_buffers 128MB,
work_mem 4MB:

relation | size
----------------------------------+------------
public.package_files_int8 | 245 MB
public.package_files | 234 MB
public.package_files_int8_pkey | 56 MB
public.package_files_pkg_id | 56 MB
public.package_files_int8_pkg_id | 56 MB
public.package_files_pkey | 56 MB

dmcgee=# select count(*) from (select * from package_files where
pkg_id in (48024, 48025, 40343) order by id) a;
119325
Time: 177.078 ms
dmcgee=# select count(*) from (select * from package_files where
pkg_id in (48024, 48025, 40343) order by id) a;
119325
Time: 176.109 ms
dmcgee=# select count(*) from (select * from package_files where
pkg_id in (48024, 48025, 40343) order by id) a;
119325
Time: 177.478 ms
dmcgee=# select count(*) from (select * from package_files where
pkg_id in (48024, 48025, 40343) order by id) a;
119325
Time: 176.639 ms
dmcgee=# select count(*) from (select * from package_files where
pkg_id in (48024, 48025, 40343) order by id) a;
119325
Time: 176.453 ms

dmcgee=# select count(*) from (select * from package_files_int8 where
pkg_id in (48024, 48025, 40343) order by id) a;
119325
Time: 185.768 ms
dmcgee=# select count(*) from (select * from package_files_int8 where
pkg_id in (48024, 48025, 40343) order by id) a;
119325
Time: 185.159 ms
dmcgee=# select count(*) from (select * from package_files_int8 where
pkg_id in (48024, 48025, 40343) order by id) a;
119325
Time: 184.407 ms
dmcgee=# select count(*) from (select * from package_files_int8 where
pkg_id in (48024, 48025, 40343) order by id) a;
119325
Time: 184.555 ms
dmcgee=# select count(*) from (select * from package_files_int8 where
pkg_id in (48024, 48025, 40343) order by id) a;
119325
Time: 184.290 ms

Overall results:

i686 x86_64
int4 int8 int4 int8
516.558 731.194 177.078 185.768
519.72 730.329 176.109 185.159
533.33 724.646 177.478 184.407
519.095 710.815 176.639 184.555
520.253 724.519 176.453 184.29

Average 521.7912 724.3006 176.7514 184.8358
Stddev 6.6040841681 8.1530512264 0.5359499044 0.619288059
Ratio 1.3881042839 1.0457388173

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Re: Observation on integer types documentation

From

Dan McGee

Date:

21 May 2012, 12:34:19

Yes, I didn't see any difference in query plans between the two.

-Dan

On Sun, May 13, 2012 at 7:08 PM, Marcelo Sena <marceloslacerda@gmail.com> wrote:
> I'm new here but your proposal makes sense to me. Are the query plans equal
> on both architectures?
>
> --
> Marcelo Lacerda
>
>
> On Mon, Apr 30, 2012 at 5:59 PM, Dan McGee <dpmcgee@gmail.com> wrote:
>>
>> Hey everyone,
>>
>> Reading the docs today, I came across this paragraph
>>
>> (http://www.postgresql.org/docs/devel/static/datatype-numeric.html#DATATYPE-INT),
>> which goes back several major versions:
>>
>> > The type integer is the common choice, as it offers the best balance
>> > between range, storage size, and performance. The smallint type is generally
>> > only used if disk space is at a premium. The bigint type should only be used
>> > if the range of the integer type is insufficient, because the latter is
>> > definitely faster.
>>
>> A few thoughts on this.
>> 1) the use of the word "latter" isn't totally clear, or at least I had
>> to re-read it to realize former was 'bigint' and latter was 'integer'.
>> It might just be the style of writing.
>> 2) I'm less than convinced this note belongs in modern documentation,
>> and set out to test that theory. My full results are below, but the
>> summary is this: on a 64-bit system, there seems to be only a minimal
>> measurable performance difference (< 5%) and very little size
>> difference. In the case of the indexes, the size difference is zero.
>> This is not true for a 32-bit system (where it is 39% slower), but the
>> blanket statement doesn't hold true, which is why I'm writing all this
>> up.
>>
>> On a final note, the following paragraph also seems like it has
>> outlived its useful life:
>>
>> > On very minimal operating systems the bigint type might not function
>> > correctly, because it relies on compiler support for eight-byte integers. On
>> > such machines, bigint acts the same as integer, but still takes up eight
>> > bytes of storage. (We are not aware of any modern platform where this is the
>> > case.)
>>
>> Thanks!
>> -Dan
>>
>>
>> Table setup (only difference is type of 'id' column):
>>
>> Table "public.package_files"
>>    Column    |          Type          |       Modifiers
>> --------------+------------------------+------------------------
>>  id           | integer                | not null
>>  pkg_id       | integer                | not null
>>  is_directory | boolean                | not null default false
>>  directory    | character varying(255) | not null
>>  filename     | character varying(255) |
>> Indexes:
>>    "package_files_pkey" PRIMARY KEY, btree (id)
>>    "package_files_pkg_id" btree (pkg_id) CLUSTER
>>
>>
>> Table "public.package_files_int8"
>>    Column    |          Type          |       Modifiers
>> --------------+------------------------+------------------------
>>  id           | bigint                 | not null
>>  pkg_id       | integer                | not null
>>  is_directory | boolean                | not null default false
>>  directory    | character varying(255) | not null
>>  filename     | character varying(255) |
>> Indexes:
>>    "package_files_int8_pkey" PRIMARY KEY, btree (id)
>>    "package_files_int8_pkg_id" btree (pkg_id) CLUSTER
>>
>>
>> # select count(*) from package_files;
>>  2621418
>> # select count(*) from package_files_int8 ;
>>  2621418
>>
>>
>> All runs below were done after issuing a few warm up queries, and both
>> tables went through a VACUUM/CLUSTER/ANALYZE sequence.
>>
>> 32-bit P4 2.4 GHz (single core). no enabled CPU frequency scaling, 1GB
>> total ram, shared_buffers 128MB, work_mem 4MB:
>>
>>             relation             |    size
>> ----------------------------------+------------
>>  public.package_files_int8        | 239 MB
>>  public.package_files             | 229 MB
>>  public.package_files_int8_pkey   | 56 MB
>>  public.package_files_int8_pkg_id | 45 MB
>>  public.package_files_pkey        | 45 MB
>>  public.package_files_pkg_id      | 45 MB
>>
>> archweb=> \timing on
>> Timing is on.
>> archweb=> \t
>> Showing only tuples.
>> archweb=> select count(*) from (select * from package_files where
>> pkg_id in (48024, 48025, 40343) order by id) a;
>>  119325
>> Time: 516.558 ms
>> archweb=> select count(*) from (select * from package_files where
>> pkg_id in (48024, 48025, 40343) order by id) a;
>>  119325
>> Time: 519.720 ms
>> archweb=> select count(*) from (select * from package_files where
>> pkg_id in (48024, 48025, 40343) order by id) a;
>>  119325
>> Time: 533.330 ms
>> archweb=> select count(*) from (select * from package_files where
>> pkg_id in (48024, 48025, 40343) order by id) a;
>>  119325
>> Time: 519.095 ms
>> archweb=> select count(*) from (select * from package_files where
>> pkg_id in (48024, 48025, 40343) order by id) a;
>>  119325
>> Time: 520.253 ms
>>
>> archweb=> select count(*) from (select * from package_files_int8 where
>> pkg_id in (48024, 48025, 40343) order by id) a;
>>  119325
>> Time: 731.194 ms
>> archweb=> select count(*) from (select * from package_files_int8 where
>> pkg_id in (48024, 48025, 40343) order by id) a;
>>  119325
>> Time: 730.329 ms
>> archweb=> select count(*) from (select * from package_files_int8 where
>> pkg_id in (48024, 48025, 40343) order by id) a;
>>  119325
>> Time: 724.646 ms
>> archweb=> select count(*) from (select * from package_files_int8 where
>> pkg_id in (48024, 48025, 40343) order by id) a;
>>  119325
>> Time: 710.815 ms
>> archweb=> select count(*) from (select * from package_files_int8 where
>> pkg_id in (48024, 48025, 40343) order by id) a;
>>  119325
>> Time: 724.519 ms
>>
>>
>>
>>
>> 64-bit Core2 Quad 2.66 GHz (four core), CPU freq scaling disabled
>> (performance governor used), 8GB total ram, shared_buffers 128MB,
>> work_mem 4MB:
>>
>>             relation             |    size
>> ----------------------------------+------------
>>  public.package_files_int8        | 245 MB
>>  public.package_files             | 234 MB
>>  public.package_files_int8_pkey   | 56 MB
>>  public.package_files_pkg_id      | 56 MB
>>  public.package_files_int8_pkg_id | 56 MB
>>  public.package_files_pkey        | 56 MB
>>
>> dmcgee=# select count(*) from (select * from package_files where
>> pkg_id in (48024, 48025, 40343) order by id) a;
>>  119325
>> Time: 177.078 ms
>> dmcgee=# select count(*) from (select * from package_files where
>> pkg_id in (48024, 48025, 40343) order by id) a;
>>  119325
>> Time: 176.109 ms
>> dmcgee=# select count(*) from (select * from package_files where
>> pkg_id in (48024, 48025, 40343) order by id) a;
>>  119325
>> Time: 177.478 ms
>> dmcgee=# select count(*) from (select * from package_files where
>> pkg_id in (48024, 48025, 40343) order by id) a;
>>  119325
>> Time: 176.639 ms
>> dmcgee=# select count(*) from (select * from package_files where
>> pkg_id in (48024, 48025, 40343) order by id) a;
>>  119325
>> Time: 176.453 ms
>>
>> dmcgee=# select count(*) from (select * from package_files_int8 where
>> pkg_id in (48024, 48025, 40343) order by id) a;
>>  119325
>> Time: 185.768 ms
>> dmcgee=# select count(*) from (select * from package_files_int8 where
>> pkg_id in (48024, 48025, 40343) order by id) a;
>>  119325
>> Time: 185.159 ms
>> dmcgee=# select count(*) from (select * from package_files_int8 where
>> pkg_id in (48024, 48025, 40343) order by id) a;
>>  119325
>> Time: 184.407 ms
>> dmcgee=# select count(*) from (select * from package_files_int8 where
>> pkg_id in (48024, 48025, 40343) order by id) a;
>>  119325
>> Time: 184.555 ms
>> dmcgee=# select count(*) from (select * from package_files_int8 where
>> pkg_id in (48024, 48025, 40343) order by id) a;
>>  119325
>> Time: 184.290 ms
>>
>>
>> Overall results:
>>
>>                       i686                            x86_64
>>                int4            int8            int4            int8
>>                516.558         731.194         177.078         185.768
>>                519.72          730.329         176.109         185.159
>>                533.33          724.646         177.478         184.407
>>                519.095         710.815         176.639         184.555
>>                520.253         724.519         176.453         184.29
>>
>>
>>
>> Average         521.7912        724.3006        176.7514        184.8358
>> Stddev          6.6040841681    8.1530512264    0.5359499044
>>  0.619288059
>> Ratio                   1.3881042839                    1.0457388173
>>
>> --
>> Sent via pgsql-docs mailing list (pgsql-docs@postgresql.org)
>> To make changes to your subscription:
>> http://www.postgresql.org/mailpref/pgsql-docs
>
>

Re: Observation on integer types documentation

From

Bruce Momjian

Date:

30 August 2012, 01:38:57

I have developed the attached patch based on your observations.

---------------------------------------------------------------------------

On Mon, Apr 30, 2012 at 03:59:20PM -0500, Dan McGee wrote:
> Hey everyone,
>
> Reading the docs today, I came across this paragraph
> (http://www.postgresql.org/docs/devel/static/datatype-numeric.html#DATATYPE-INT),
> which goes back several major versions:
>
> > The type integer is the common choice, as it offers the best balance between range, storage size, and performance.
Thesmallint type is generally only used if disk space is at a premium. The bigint type should only be used if the range
ofthe integer type is insufficient, because the latter is definitely faster. 
>
> A few thoughts on this.
> 1) the use of the word "latter" isn't totally clear, or at least I had
> to re-read it to realize former was 'bigint' and latter was 'integer'.
> It might just be the style of writing.
> 2) I'm less than convinced this note belongs in modern documentation,
> and set out to test that theory. My full results are below, but the
> summary is this: on a 64-bit system, there seems to be only a minimal
> measurable performance difference (< 5%) and very little size
> difference. In the case of the indexes, the size difference is zero.
> This is not true for a 32-bit system (where it is 39% slower), but the
> blanket statement doesn't hold true, which is why I'm writing all this
> up.
>
> On a final note, the following paragraph also seems like it has
> outlived its useful life:
>
> > On very minimal operating systems the bigint type might not function correctly, because it relies on compiler
supportfor eight-byte integers. On such machines, bigint acts the same as integer, but still takes up eight bytes of
storage.(We are not aware of any modern platform where this is the case.) 
>
> Thanks!
> -Dan
>
>
> Table setup (only difference is type of 'id' column):
>
> Table "public.package_files"
>     Column    |          Type          |       Modifiers
> --------------+------------------------+------------------------
>  id           | integer                | not null
>  pkg_id       | integer                | not null
>  is_directory | boolean                | not null default false
>  directory    | character varying(255) | not null
>  filename     | character varying(255) |
> Indexes:
>     "package_files_pkey" PRIMARY KEY, btree (id)
>     "package_files_pkg_id" btree (pkg_id) CLUSTER
>
>
> Table "public.package_files_int8"
>     Column    |          Type          |       Modifiers
> --------------+------------------------+------------------------
>  id           | bigint                 | not null
>  pkg_id       | integer                | not null
>  is_directory | boolean                | not null default false
>  directory    | character varying(255) | not null
>  filename     | character varying(255) |
> Indexes:
>     "package_files_int8_pkey" PRIMARY KEY, btree (id)
>     "package_files_int8_pkg_id" btree (pkg_id) CLUSTER
>
>
> # select count(*) from package_files;
>  2621418
> # select count(*) from package_files_int8 ;
>  2621418
>
>
> All runs below were done after issuing a few warm up queries, and both
> tables went through a VACUUM/CLUSTER/ANALYZE sequence.
>
> 32-bit P4 2.4 GHz (single core). no enabled CPU frequency scaling, 1GB
> total ram, shared_buffers 128MB, work_mem 4MB:
>
>              relation             |    size
> ----------------------------------+------------
>  public.package_files_int8        | 239 MB
>  public.package_files             | 229 MB
>  public.package_files_int8_pkey   | 56 MB
>  public.package_files_int8_pkg_id | 45 MB
>  public.package_files_pkey        | 45 MB
>  public.package_files_pkg_id      | 45 MB
>
> archweb=> \timing on
> Timing is on.
> archweb=> \t
> Showing only tuples.
> archweb=> select count(*) from (select * from package_files where
> pkg_id in (48024, 48025, 40343) order by id) a;
>  119325
> Time: 516.558 ms
> archweb=> select count(*) from (select * from package_files where
> pkg_id in (48024, 48025, 40343) order by id) a;
>  119325
> Time: 519.720 ms
> archweb=> select count(*) from (select * from package_files where
> pkg_id in (48024, 48025, 40343) order by id) a;
>  119325
> Time: 533.330 ms
> archweb=> select count(*) from (select * from package_files where
> pkg_id in (48024, 48025, 40343) order by id) a;
>  119325
> Time: 519.095 ms
> archweb=> select count(*) from (select * from package_files where
> pkg_id in (48024, 48025, 40343) order by id) a;
>  119325
> Time: 520.253 ms
>
> archweb=> select count(*) from (select * from package_files_int8 where
> pkg_id in (48024, 48025, 40343) order by id) a;
>  119325
> Time: 731.194 ms
> archweb=> select count(*) from (select * from package_files_int8 where
> pkg_id in (48024, 48025, 40343) order by id) a;
>  119325
> Time: 730.329 ms
> archweb=> select count(*) from (select * from package_files_int8 where
> pkg_id in (48024, 48025, 40343) order by id) a;
>  119325
> Time: 724.646 ms
> archweb=> select count(*) from (select * from package_files_int8 where
> pkg_id in (48024, 48025, 40343) order by id) a;
>  119325
> Time: 710.815 ms
> archweb=> select count(*) from (select * from package_files_int8 where
> pkg_id in (48024, 48025, 40343) order by id) a;
>  119325
> Time: 724.519 ms
>
>
>
>
> 64-bit Core2 Quad 2.66 GHz (four core), CPU freq scaling disabled
> (performance governor used), 8GB total ram, shared_buffers 128MB,
> work_mem 4MB:
>
>              relation             |    size
> ----------------------------------+------------
>  public.package_files_int8        | 245 MB
>  public.package_files             | 234 MB
>  public.package_files_int8_pkey   | 56 MB
>  public.package_files_pkg_id      | 56 MB
>  public.package_files_int8_pkg_id | 56 MB
>  public.package_files_pkey        | 56 MB
>
> dmcgee=# select count(*) from (select * from package_files where
> pkg_id in (48024, 48025, 40343) order by id) a;
>  119325
> Time: 177.078 ms
> dmcgee=# select count(*) from (select * from package_files where
> pkg_id in (48024, 48025, 40343) order by id) a;
>  119325
> Time: 176.109 ms
> dmcgee=# select count(*) from (select * from package_files where
> pkg_id in (48024, 48025, 40343) order by id) a;
>  119325
> Time: 177.478 ms
> dmcgee=# select count(*) from (select * from package_files where
> pkg_id in (48024, 48025, 40343) order by id) a;
>  119325
> Time: 176.639 ms
> dmcgee=# select count(*) from (select * from package_files where
> pkg_id in (48024, 48025, 40343) order by id) a;
>  119325
> Time: 176.453 ms
>
> dmcgee=# select count(*) from (select * from package_files_int8 where
> pkg_id in (48024, 48025, 40343) order by id) a;
>  119325
> Time: 185.768 ms
> dmcgee=# select count(*) from (select * from package_files_int8 where
> pkg_id in (48024, 48025, 40343) order by id) a;
>  119325
> Time: 185.159 ms
> dmcgee=# select count(*) from (select * from package_files_int8 where
> pkg_id in (48024, 48025, 40343) order by id) a;
>  119325
> Time: 184.407 ms
> dmcgee=# select count(*) from (select * from package_files_int8 where
> pkg_id in (48024, 48025, 40343) order by id) a;
>  119325
> Time: 184.555 ms
> dmcgee=# select count(*) from (select * from package_files_int8 where
> pkg_id in (48024, 48025, 40343) order by id) a;
>  119325
> Time: 184.290 ms
>
>
> Overall results:
>
>                        i686                            x86_64
>                 int4            int8            int4            int8
>                 516.558         731.194         177.078         185.768
>                 519.72          730.329         176.109         185.159
>                 533.33          724.646         177.478         184.407
>                 519.095         710.815         176.639         184.555
>                 520.253         724.519         176.453         184.29
>
>
>
> Average         521.7912        724.3006        176.7514        184.8358
> Stddev          6.6040841681    8.1530512264    0.5359499044    0.619288059
> Ratio                   1.3881042839                    1.0457388173
>
> --
> Sent via pgsql-docs mailing list (pgsql-docs@postgresql.org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-docs

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + It's impossible for everything to be true. +

Attachment

bigint.diff

Re: Observation on integer types documentation

From

Bruce Momjian

Date:

30 August 2012, 20:13:46

On Wed, Aug 29, 2012 at 06:38:47PM -0400, Bruce Momjian wrote:
>
> I have developed the attached patch based on your observations.

Applied.

---------------------------------------------------------------------------

>
> On Mon, Apr 30, 2012 at 03:59:20PM -0500, Dan McGee wrote:
> > Hey everyone,
> >
> > Reading the docs today, I came across this paragraph
> > (http://www.postgresql.org/docs/devel/static/datatype-numeric.html#DATATYPE-INT),
> > which goes back several major versions:
> >
> > > The type integer is the common choice, as it offers the best balance between range, storage size, and
performance.The smallint type is generally only used if disk space is at a premium. The bigint type should only be used
ifthe range of the integer type is insufficient, because the latter is definitely faster. 
> >
> > A few thoughts on this.
> > 1) the use of the word "latter" isn't totally clear, or at least I had
> > to re-read it to realize former was 'bigint' and latter was 'integer'.
> > It might just be the style of writing.
> > 2) I'm less than convinced this note belongs in modern documentation,
> > and set out to test that theory. My full results are below, but the
> > summary is this: on a 64-bit system, there seems to be only a minimal
> > measurable performance difference (< 5%) and very little size
> > difference. In the case of the indexes, the size difference is zero.
> > This is not true for a 32-bit system (where it is 39% slower), but the
> > blanket statement doesn't hold true, which is why I'm writing all this
> > up.
> >
> > On a final note, the following paragraph also seems like it has
> > outlived its useful life:
> >
> > > On very minimal operating systems the bigint type might not function correctly, because it relies on compiler
supportfor eight-byte integers. On such machines, bigint acts the same as integer, but still takes up eight bytes of
storage.(We are not aware of any modern platform where this is the case.) 
> >
> > Thanks!
> > -Dan
> >
> >
> > Table setup (only difference is type of 'id' column):
> >
> > Table "public.package_files"
> >     Column    |          Type          |       Modifiers
> > --------------+------------------------+------------------------
> >  id           | integer                | not null
> >  pkg_id       | integer                | not null
> >  is_directory | boolean                | not null default false
> >  directory    | character varying(255) | not null
> >  filename     | character varying(255) |
> > Indexes:
> >     "package_files_pkey" PRIMARY KEY, btree (id)
> >     "package_files_pkg_id" btree (pkg_id) CLUSTER
> >
> >
> > Table "public.package_files_int8"
> >     Column    |          Type          |       Modifiers
> > --------------+------------------------+------------------------
> >  id           | bigint                 | not null
> >  pkg_id       | integer                | not null
> >  is_directory | boolean                | not null default false
> >  directory    | character varying(255) | not null
> >  filename     | character varying(255) |
> > Indexes:
> >     "package_files_int8_pkey" PRIMARY KEY, btree (id)
> >     "package_files_int8_pkg_id" btree (pkg_id) CLUSTER
> >
> >
> > # select count(*) from package_files;
> >  2621418
> > # select count(*) from package_files_int8 ;
> >  2621418
> >
> >
> > All runs below were done after issuing a few warm up queries, and both
> > tables went through a VACUUM/CLUSTER/ANALYZE sequence.
> >
> > 32-bit P4 2.4 GHz (single core). no enabled CPU frequency scaling, 1GB
> > total ram, shared_buffers 128MB, work_mem 4MB:
> >
> >              relation             |    size
> > ----------------------------------+------------
> >  public.package_files_int8        | 239 MB
> >  public.package_files             | 229 MB
> >  public.package_files_int8_pkey   | 56 MB
> >  public.package_files_int8_pkg_id | 45 MB
> >  public.package_files_pkey        | 45 MB
> >  public.package_files_pkg_id      | 45 MB
> >
> > archweb=> \timing on
> > Timing is on.
> > archweb=> \t
> > Showing only tuples.
> > archweb=> select count(*) from (select * from package_files where
> > pkg_id in (48024, 48025, 40343) order by id) a;
> >  119325
> > Time: 516.558 ms
> > archweb=> select count(*) from (select * from package_files where
> > pkg_id in (48024, 48025, 40343) order by id) a;
> >  119325
> > Time: 519.720 ms
> > archweb=> select count(*) from (select * from package_files where
> > pkg_id in (48024, 48025, 40343) order by id) a;
> >  119325
> > Time: 533.330 ms
> > archweb=> select count(*) from (select * from package_files where
> > pkg_id in (48024, 48025, 40343) order by id) a;
> >  119325
> > Time: 519.095 ms
> > archweb=> select count(*) from (select * from package_files where
> > pkg_id in (48024, 48025, 40343) order by id) a;
> >  119325
> > Time: 520.253 ms
> >
> > archweb=> select count(*) from (select * from package_files_int8 where
> > pkg_id in (48024, 48025, 40343) order by id) a;
> >  119325
> > Time: 731.194 ms
> > archweb=> select count(*) from (select * from package_files_int8 where
> > pkg_id in (48024, 48025, 40343) order by id) a;
> >  119325
> > Time: 730.329 ms
> > archweb=> select count(*) from (select * from package_files_int8 where
> > pkg_id in (48024, 48025, 40343) order by id) a;
> >  119325
> > Time: 724.646 ms
> > archweb=> select count(*) from (select * from package_files_int8 where
> > pkg_id in (48024, 48025, 40343) order by id) a;
> >  119325
> > Time: 710.815 ms
> > archweb=> select count(*) from (select * from package_files_int8 where
> > pkg_id in (48024, 48025, 40343) order by id) a;
> >  119325
> > Time: 724.519 ms
> >
> >
> >
> >
> > 64-bit Core2 Quad 2.66 GHz (four core), CPU freq scaling disabled
> > (performance governor used), 8GB total ram, shared_buffers 128MB,
> > work_mem 4MB:
> >
> >              relation             |    size
> > ----------------------------------+------------
> >  public.package_files_int8        | 245 MB
> >  public.package_files             | 234 MB
> >  public.package_files_int8_pkey   | 56 MB
> >  public.package_files_pkg_id      | 56 MB
> >  public.package_files_int8_pkg_id | 56 MB
> >  public.package_files_pkey        | 56 MB
> >
> > dmcgee=# select count(*) from (select * from package_files where
> > pkg_id in (48024, 48025, 40343) order by id) a;
> >  119325
> > Time: 177.078 ms
> > dmcgee=# select count(*) from (select * from package_files where
> > pkg_id in (48024, 48025, 40343) order by id) a;
> >  119325
> > Time: 176.109 ms
> > dmcgee=# select count(*) from (select * from package_files where
> > pkg_id in (48024, 48025, 40343) order by id) a;
> >  119325
> > Time: 177.478 ms
> > dmcgee=# select count(*) from (select * from package_files where
> > pkg_id in (48024, 48025, 40343) order by id) a;
> >  119325
> > Time: 176.639 ms
> > dmcgee=# select count(*) from (select * from package_files where
> > pkg_id in (48024, 48025, 40343) order by id) a;
> >  119325
> > Time: 176.453 ms
> >
> > dmcgee=# select count(*) from (select * from package_files_int8 where
> > pkg_id in (48024, 48025, 40343) order by id) a;
> >  119325
> > Time: 185.768 ms
> > dmcgee=# select count(*) from (select * from package_files_int8 where
> > pkg_id in (48024, 48025, 40343) order by id) a;
> >  119325
> > Time: 185.159 ms
> > dmcgee=# select count(*) from (select * from package_files_int8 where
> > pkg_id in (48024, 48025, 40343) order by id) a;
> >  119325
> > Time: 184.407 ms
> > dmcgee=# select count(*) from (select * from package_files_int8 where
> > pkg_id in (48024, 48025, 40343) order by id) a;
> >  119325
> > Time: 184.555 ms
> > dmcgee=# select count(*) from (select * from package_files_int8 where
> > pkg_id in (48024, 48025, 40343) order by id) a;
> >  119325
> > Time: 184.290 ms
> >
> >
> > Overall results:
> >
> >                        i686                            x86_64
> >                 int4            int8            int4            int8
> >                 516.558         731.194         177.078         185.768
> >                 519.72          730.329         176.109         185.159
> >                 533.33          724.646         177.478         184.407
> >                 519.095         710.815         176.639         184.555
> >                 520.253         724.519         176.453         184.29
> >
> >
> >
> > Average         521.7912        724.3006        176.7514        184.8358
> > Stddev          6.6040841681    8.1530512264    0.5359499044    0.619288059
> > Ratio                   1.3881042839                    1.0457388173
> >
> > --
> > Sent via pgsql-docs mailing list (pgsql-docs@postgresql.org)
> > To make changes to your subscription:
> > http://www.postgresql.org/mailpref/pgsql-docs
>
> --
>   Bruce Momjian  <bruce@momjian.us>        http://momjian.us
>   EnterpriseDB                             http://enterprisedb.com
>
>   + It's impossible for everything to be true. +

> diff --git a/doc/src/sgml/datatype.sgml b/doc/src/sgml/datatype.sgml
> new file mode 100644
> index 7f6e661..71cf59e
> *** a/doc/src/sgml/datatype.sgml
> --- b/doc/src/sgml/datatype.sgml
> ***************
> *** 453,470 ****
>        The type <type>integer</type> is the common choice, as it offers
>        the best balance between range, storage size, and performance.
>        The <type>smallint</type> type is generally only used if disk
> !      space is at a premium.  The <type>bigint</type> type should only
> !      be used if the range of the <type>integer</type> type is insufficient,
> !      because the latter is definitely faster.
> !     </para>
> !
> !     <para>
> !      On very minimal operating systems the <type>bigint</type> type
> !      might not function correctly, because it relies on compiler support
> !      for eight-byte integers.  On such machines, <type>bigint</type>
> !      acts the same as <type>integer</type>, but still takes up eight
> !      bytes of storage.  (We are not aware of any modern
> !      platform where this is the case.)
>       </para>
>
>       <para>
> --- 453,460 ----
>        The type <type>integer</type> is the common choice, as it offers
>        the best balance between range, storage size, and performance.
>        The <type>smallint</type> type is generally only used if disk
> !      space is at a premium.  The <type>bigint</type> type is designed to be
> !      used when the range of the <type>integer</type> type is insufficient.
>       </para>
>
>       <para>

>
> --
> Sent via pgsql-docs mailing list (pgsql-docs@postgresql.org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-docs


--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + It's impossible for everything to be true. +