In the part 1, part 2, part 3 of the blog series, I show the examples to create compress tables using CREATE TABLE and ALTER TABLE MOVE and how to improve the compression performance using parallelism. For big database, partition table is quite common. This post shows how partition table behaves for different compression methods. There is a nice thing about partition table is that you can compress certain partitions while leave other partition uncompressed. This is very useful feature as you might need to compress historical data and only keep the current partition uncompressed. Printer manufacturer Brother has an interesting newspaper ads for its USP product shown above. Obviously this guy needs a better partition strategy as well as compression approaches to save his files digitally.
First let’s create a partition table. I made a slight change in the create table script from part 1.
CREATE TABLE PARTAB
(
ID NUMBER,
OWNER VARCHAR2(30) NOT NULL ENABLE,
OBJECT_NAME VARCHAR2(30) NOT NULL ENABLE,
SUBOBJECT_NAME VARCHAR2(30),
OBJECT_ID NUMBER NOT NULL ENABLE,
DATA_OBJECT_ID NUMBER,
OBJECT_TYPE VARCHAR2(19),
CREATED DATE NOT NULL ENABLE,
LAST_DDL_TIME DATE NOT NULL ENABLE,
TIMESTAMP VARCHAR2(19),
STATUS VARCHAR2(7),
TEMPORARY VARCHAR2(1),
GENERATED VARCHAR2(1),
SECONDARY VARCHAR2(1),
NAMESPACE NUMBER NOT NULL ENABLE,
EDITION_NAME VARCHAR2(30)
)
PARTITION BY RANGE (OBJECT_ID)
(PARTITION P1 values less than (1500),
PARTITION P2 values less than (4000),
PARTITION P3 values less than (6000),
PARTITION P4 values less than (maxvalue)
);
Then, populate some data with 10 million rows in total.
declare
l_cnt number;
l_rows number := 10000000;
begin
insert /*+ append */
into partab
select rownum, a.*
from all_objects a;
l_cnt := sql%rowcount;
commit;
while (l_cnt < l_rows)
loop
insert /*+ APPEND */ into partab
select rownum+l_cnt,
OWNER, OBJECT_NAME, SUBOBJECT_NAME,
OBJECT_ID, DATA_OBJECT_ID,
OBJECT_TYPE, CREATED, LAST_DDL_TIME,
TIMESTAMP, STATUS, TEMPORARY,
GENERATED, SECONDARY, NAMESPACE, EDITION_NAME
from partab
where rownum <= l_rows-l_cnt; l_cnt := l_cnt + sql%rowcount; commit; end loop; end; /
Check out the row count and table size.
WZHOU@dbm1> select count(*) from partab; COUNT(*) ---------- 10000000 Elapsed: 00:00:07.43 WZHOU@dbm1> select count(*) from partab partition(p1); COUNT(*) ---------- 1364992 Elapsed: 00:00:00.08 WZHOU@dbm1> select count(*) from partab partition(p2); COUNT(*) ---------- 2560000 Elapsed: 00:00:00.15 WZHOU@dbm1> select count(*) from partab partition(p3); COUNT(*) ---------- 1445504 Elapsed: 00:00:00.08 WZHOU@dbm1> select count(*) from partab partition(p4); COUNT(*) ---------- 4629504 Elapsed: 00:00:00.27
Before doing the compression work, let me check out the table size and partition size. You can find part_size.sql from the Script page. This script is also one of the Enkitec scripts I use frequently.
WZHOU@dbm1> @table_size
Enter value for owner: WZHOU
Enter value for table_name: PARTAB
Enter value for type:
OWNER SEGMENT_NAME TYPE TOTALSIZE_MEGS TABLESPACE_NAME
------ ------------ ---------------- -------------- ------------------------------
WZHOU PARTAB TABLE PARTITION 1,112.0 USERS
--------------
sum 1,112.0
WZHOU@dbm1> @part_size
Enter value for owner: WZHOU
Enter value for table_name: PARTAB
Enter value for partition_name:
Enter value for type:
OWNER SEGMENT_NAME PARTITION_NAME TYPE TOTALSIZE_MEGS TABLESPACE_NAME
------ ------------ -------------- --------------- -------------- ---------------
WZHOU PARTAB P1 TABLE PARTITION 152.0 USERS
WZHOU PARTAB P2 TABLE PARTITION 280.0 USERS
WZHOU PARTAB P3 TABLE PARTITION 152.0 USERS
WZHOU PARTAB P4 TABLE PARTITION 528.0 USERS
--------------
sum 1,112.0
Right now, let me start with the Basic compression.
Basic Compression
WZHOU@dbm1> ALTER TABLE partab MOVE partition p4 COMPRESS;
Table altered.
Elapsed: 00:00:14.00
WZHOU@dbm1> select table_owner,table_name,partition_name,compress_for from DBA_TAB_PARTITIONS
where table_name = 'PARTAB' and partition_name='P4';
TABLE_OWNER TABLE_NAME PARTITION_NAME COMPRESS_FOR
----------- ---------- -------------- ------------
WZHOU PARTAB P4 BASIC
WZHOU@dbm1> @part_size
Enter value for owner: WZHOU
Enter value for table_name: PARTAB
Enter value for partition_name: P4
Enter value for type:
OWNER SEGMENT_NAME PARTITION_NAME TYPE TOTALSIZE_MEGS TABLESPACE_NAME
------ ------------ -------------- --------------- -------------- ---------------
WZHOU PARTAB P4 TABLE PARTITION 192.0 USERS
--------------
sum 192.0
There is little change we need to make before we proceed to the next test. We need to restore this partition to the non-compression stage by using nocompress keyword.
OLTP Compression
WZHOU@dbm1> ALTER TABLE partab MOVE partition p4 nocompress;
Table altered.
Elapsed: 00:00:05.99
WZHOU@dbm1> ALTER TABLE partab MOVE partition p4 compress for oltp;
Table altered.
Elapsed: 00:00:14.22
WZHOU@dbm1> select table_owner,table_name,partition_name,compress_for from DBA_TAB_PARTITIONS where table_name = 'PARTAB' and partition_name='P4';
TABLE_OWNER TABLE_NAME PARTITION_NAME COMPRESS_FOR
----------- ---------- -------------- ------------
WZHOU PARTAB P4 OLTP
Elapsed: 00:00:00.01
WZHOU@dbm1> @part_size
Enter value for owner: WZHOU
Enter value for table_name: PARTAB
Enter value for partition_name: P4
Enter value for type:
OWNER SEGMENT_NAME PARTITION_NAME TYPE TOTALSIZE_MEGS TABLESPACE_NAME
------ ------------ -------------- --------------- -------------- ---------------
WZHOU PARTAB P4 TABLE PARTITION 192.0 USERS
--------------
sum 192.0
Query Low Compression
WZHOU@dbm1> ALTER TABLE partab MOVE partition p4 nocompress;
Table altered.
Elapsed: 00:00:06.01
WZHOU@dbm1> ALTER TABLE partab MOVE partition p4 compress for query low;
Table altered.
Elapsed: 00:00:06.83
WZHOU@dbm1> select table_owner,table_name,partition_name,compress_for from DBA_TAB_PARTITIONS
where table_name = 'PARTAB' and partition_name='P4';
TABLE_OWNER TABLE_NAME PARTITION_NAME COMPRESS_FOR
----------- ---------- -------------- ------------
WZHOU PARTAB P4 QUERY LOW
Elapsed: 00:00:00.01
WZHOU@dbm1> @part_size
Enter value for owner: WZHOU
Enter value for table_name: PARTAB
Enter value for partition_name: P4
Enter value for type:
OWNER SEGMENT_NAME PARTITION_NAME TYPE TOTALSIZE_MEGS TABLESPACE_NAME
------ ------------ -------------- --------------- -------------- ---------------
WZHOU PARTAB P4 TABLE PARTITION 80.0 USERS
--------------
sum 80.0
Query High Compression
WZHOU@dbm1> ALTER TABLE partab MOVE partition p4 nocompress;
Table altered.
Elapsed: 00:00:05.26
WZHOU@dbm1> ALTER TABLE partab MOVE partition p4 compress for query high;
Table altered.
Elapsed: 00:00:13.08
WZHOU@dbm1> select table_owner,table_name,partition_name,compress_for from DBA_TAB_PARTITIONS
where table_name = 'PARTAB' and partition_name='P4';
TABLE_OWNER TABLE_NAME PARTITION_NAME COMPRESS_FOR
----------- ---------- -------------- ------------
WZHOU PARTAB P4 QUERY HIGH
Elapsed: 00:00:00.01
WZHOU@dbm1> @part_size
Enter value for owner: WZHOU
Enter value for table_name: PARTAB
Enter value for partition_name: P4
Enter value for type:
OWNER SEGMENT_NAME PARTITION_NAME TYPE TOTALSIZE_MEGS TABLESPACE_NAME
------ ------------ -------------- --------------- -------------- ---------------
WZHOU PARTAB P4 TABLE PARTITION 32.0 USERS
--------------
sum 32.0
Archive Low Compression
WZHOU@dbm1> ALTER TABLE partab MOVE partition p4 nocompress;
Table altered.
Elapsed: 00:00:05.09
WZHOU@dbm1> ALTER TABLE partab MOVE partition p4 compress for archive low;
Table altered.
Elapsed: 00:00:13.60
WZHOU@dbm1> select table_owner,table_name,partition_name,compress_for from DBA_TAB_PARTITIONS
where table_name = 'PARTAB' and partition_name='P4';
TABLE_OWNER TABLE_NAME PARTITION_NAME COMPRESS_FOR
----------- ---------- -------------- ------------
WZHOU PARTAB P4 ARCHIVE LOW
Elapsed: 00:00:00.00
WZHOU@dbm1> @part_size
Enter value for owner: WZHOU
Enter value for table_name: PARTAB
Enter value for partition_name: P4
Enter value for type:
OWNER SEGMENT_NAME PARTITION_NAME TYPE TOTALSIZE_MEGS TABLESPACE_NAME
------ ------------ -------------- --------------- -------------- ---------------
WZHOU PARTAB P4 TABLE PARTITION 32.0 USERS
--------------
sum 32.0
Archive High Compression
WZHOU@dbm1> ALTER TABLE partab MOVE partition p4 nocompress;
Table altered.
Elapsed: 00:00:04.93
WZHOU@dbm1> ALTER TABLE partab MOVE partition p4 compress for archive high;
Table altered.
Elapsed: 00:01:13.33
WZHOU@dbm1> select table_owner,table_name,partition_name,compress_for from DBA_TAB_PARTITIONS
where table_name = 'PARTAB' and partition_name='P4';
TABLE_OWNER TABLE_NAME PARTITION_NAME COMPRESS_FOR
----------- ---------- -------------- ------------
WZHOU PARTAB P4 ARCHIVE HIGH
Elapsed: 00:00:00.01
WZHOU@dbm1> @part_size
Enter value for owner: WZHOU
Enter value for table_name: PARTAB
Enter value for partition_name: P4
Enter value for type:
OWNER SEGMENT_NAME PARTITION_NAME TYPE TOTALSIZE_MEGS TABLESPACE_NAME
------ ------------ -------------- --------------- -------------- ---------------
WZHOU PARTAB P4 TABLE PARTITION 24.0 USERS
--------------
sum 24.0
The timing is quite different from 13 seconds on majority of compression methods to about 73 seconds on Archive High method, about 500% time increase. The compression ratio is similar to what we see in the non-partition table. The partition size drops from 528 MB to about 25~40 MB for most of compression methods.
There is another interest aspect in partition tables is that you can use different compression methods for different partitions. This is useful that allows to compress the recent data in faster methods while very old historical data can use a method with longer processing time, but higher compression ratio. Here is the test to show different compression methods for different partitions.
WZHOU@dbm1> ALTER TABLE partab MOVE partition p1 compress for query low;
Table altered.
Elapsed: 00:00:01.88
WZHOU@dbm1> ALTER TABLE partab MOVE partition p2 compress for query high;
Table altered.
Elapsed: 00:00:05.75
WZHOU@dbm1> ALTER TABLE partab MOVE partition p3 compress for archive low;
Table altered.
Elapsed: 00:00:02.34
WZHOU@dbm1> select table_owner,table_name,partition_name,compress_for from DBA_TAB_PARTITIONS
where table_name = 'PARTAB';
TABLE_OWNER TABLE_NAME PARTITION_NAME COMPRESS_FOR
----------- ---------- -------------- ------------
WZHOU PARTAB P1 QUERY LOW
WZHOU PARTAB P2 QUERY HIGH
WZHOU PARTAB P3 ARCHIVE LOW
WZHOU PARTAB P4 ARCHIVE HIGH
Elapsed: 00:00:00.04
WZHOU@dbm1> @part_size
Enter value for owner: WZHOU
Enter value for table_name: PARTAB
Enter value for partition_name:
Enter value for type:
OWNER SEGMENT_NAME PARTITION_NAME TYPE TOTALSIZE_MEGS TABLESPACE_NAME
------ ------------ -------------- --------------- -------------- ---------------
WZHOU PARTAB P1 TABLE PARTITION 16.0 USERS
WZHOU PARTAB P2 TABLE PARTITION 16.0 USERS
WZHOU PARTAB P3 TABLE PARTITION 8.0 USERS
WZHOU PARTAB P4 TABLE PARTITION 24.0 USERS
--------------
sum 64.0
See enough code? In the next part, I am going to go back the basic stuff and discuss the layout of HCC as well as some recommendation when to use and when not to use HCC.
