Friday, November 30, 2018

TDE–How to implement TDE in your database and what to think about (part 2)

This is the second part in a series on implementing TDE and what happens to the sizing.

At first my plan was to encrypt the dataset I created in my first post, but instead I compressed it.

At this point (and throughout this post), I am working with an un-encrypted dataset.

One of the first things to understand about Encryption is that encrypted data DOES NOT compress.
This is critical when understanding what happens when you implement TDE.

One way to save storage when implementing TDE is to implement encryption AND compression together.

In order to break down the affects of encryption on compressed data VS uncompressed data, I took my dataset (the SOE dataset from swing bench) and I compressed it.  I implemented Advanced compression on the tables, and I compressed the indexes and rebuilt them.

I now have 2 copies of the same dataset. 1 is compressed, and 1 is not.

Now let's take a look at the sizing of the Data sets and I will go through the same backup procedures and see what happens.

SEGMENT_NAME              SEGMENT_TYPE Space Used uncompressed   Space Used Compressed SPACE_SAVINGS
------------------------- ------------ ------------------------- -------------------- -------------
ADDRESSES                 TABLE           3,392 MB                  3,264 MB                      3
ADDRESS_CUST_IX           INDEX             703 MB                    728 MB                     -3
ADDRESS_PK                INDEX             662 MB                    888 MB                    -34
CARDDETAILS_CUST_IX       INDEX             703 MB                    562 MB                     20
CARD_DETAILS              TABLE           2,048 MB                  1,600 MB                     21
CARD_DETAILS_PK           INDEX             662 MB                      0 MB                    100
CUSTOMERS                 TABLE           3,328 MB                  2,880 MB                     13
CUSTOMERS_PK              INDEX             443 MB                      0 MB                    100
CUST_ACCOUNT_MANAGER_IX   INDEX             417 MB                    272 MB                     34
CUST_DOB_IX               INDEX             528 MB                    280 MB                     47
CUST_EMAIL_IX             INDEX             975 MB                    280 MB                     71
CUST_FUNC_LOWER_NAME_IX   INDEX             683 MB                    280 MB                     58
INVENTORIES               TABLE             176 MB                    176 MB                      0
INVENTORY_PK              INDEX              18 MB                      0 MB                    100
INV_PRODUCT_IX            INDEX              16 MB                     12 MB                     24
INV_WAREHOUSE_IX          INDEX              16 MB                     12 MB                     24
ITEM_ORDER_IX             INDEX           2,000 MB                  1,770 MB                     11
ITEM_PRODUCT_IX           INDEX           1,768 MB                  1,301 MB                     26
LOGON                     TABLE           1,728 MB                  1,728 MB                      0
ORDERENTRY_METADATA       TABLE               0 MB                      0 MB                      0
ORDERS                    TABLE           3,968 MB                  2,816 MB                     29
ORDER_ITEMS               TABLE           6,976 MB                  4,992 MB                     28
ORDER_ITEMS_PK            INDEX           2,234 MB                      0 MB                    100
ORDER_PK                  INDEX             632 MB                      0 MB                    100
ORD_CUSTOMER_IX           INDEX             671 MB                    480 MB                     28
ORD_ORDER_DATE_IX         INDEX             752 MB                    439 MB                     41
ORD_SALES_REP_IX          INDEX             594 MB                    438 MB                     26
ORD_WAREHOUSE_IX          INDEX             709 MB                    438 MB                     38
PRD_DESC_PK               INDEX               0 MB                      0 MB                    100
PRODUCT_DESCRIPTIONS      TABLE               0 MB                      0 MB                      0
PRODUCT_INFORMATION       TABLE               0 MB                      0 MB                      0
PRODUCT_INFORMATION_PK    INDEX               0 MB                      0 MB                    100
PROD_CATEGORY_IX          INDEX               0 MB                      0 MB                      0
PROD_NAME_IX              INDEX               0 MB                      0 MB                      0
PROD_SUPPLIER_IX          INDEX               0 MB                      0 MB                   -100
WAREHOUSES                TABLE               0 MB                      0 MB                      0
WAREHOUSES_PK             INDEX               0 MB                      0 MB                    100
WHS_LOCATION_IX           INDEX               0 MB                      0 MB                   -100


Here is the total savings by compressing both tables and indexes with advanced compression.

Space Used uncompressed   Space Used Compressed  SPACE_SAVINGS
------------------------- ---------------------- -------------
  36,804 MB                 25,636 MB                       30



Now to compare this with the previous data uncompressed I am going to backup by tablespace.  Below is the sizing of the backups. I used a tag to identify the backups.


-rw-rw----. 1 oracle oracle 26773323776 Nov 29 17:02 COMPRESSED_SOE.bkp
-rw-rw----. 1 oracle oracle 38441140224 Nov 29 17:04 UNCOMPRESSED_SOE.bkp
-rw-rw----. 1 oracle oracle 10987765760 Nov 29 18:35 BASIC_COMPRESSED_SOE.bkp
-rw-rw----. 1 oracle oracle 11135655936 Nov 29 18:36 BASIC_COMPRESSED_SOE_COMPRESSED.bkp
-rw-rw----. 1 oracle oracle 13360308224 Nov 29 20:12 MEDIUM_COMP_SOE_COMPRESSED.bkp
-rw-rw----. 1 oracle oracle 14383603712 Nov 29 20:12 MEDIUM_COMPRESSED_SOE_.bkp
-rw-rw----. 1 oracle oracle  9420791808 Nov 30 00:12 HIGH_COMP_SOE_COMPRESSED.bkp
-rw-rw----. 1 oracle oracle  9112944640 Nov 30 00:23 HIGH_COMPRESSED_SOE.bkp


Now I'm going to put that in a table and a chart to compare..

First the table of sizes



Now the chart


Now by looking at the chart it is apparent what happens with compression and the data.


  • Compression in the database reduced the size of the data by 30%
  • An uncompressed backupset matched the size of the data
  • Once I compressed the backupset, the difference is size was minimal.

** Bottom line - Compressing the data in the database saved on the uncompressed backupsize. Once the backupset is compressed the final size is about the same.

** Final conclusion -- Most modern backup appliances (ZDLRA, ZFS, DD) compress the backups.  When using those appliances with unencrypted data, the final size is the same regardless of whether the data is compressed in the Database.

Now that I've looked at both compressed and uncompressed data at the DB and backupset I am going to compress the data.  Next post.


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