B210 Sizing

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Module 10: Sizing

After completing this module, you will be able to:

Determine column sizing requirements based on chosen

data type.

Determine physical table row size.

Determine table sizing requirements via estimates and

empirical evidence.

Determine index sizing requirements via estimates andempirical evidence.

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Row Format

Only if Variable Length

Columns are declared.

R

o

w

Le

n

g

t

h

Row ID

Row

HashUniq.

Value

S

pa

r

e

P

r

e

s

e

nc

e

B

i

t

s

VAR

CHAR

Offsets

Fixed

Length

Columns

Uncom-

pressed

Columns

VAR

CHAR

Columns

R

e

f.

A

rr

a

y

P

t

r.

2 4 4 1 2 2 2 2 0-n Bytes 2

1 - n Bytes Data for Compressible

Columns that are neither

Compressed nor NULL.

Part.

#

Only for a V2R5 Table

with a PPI.

SELECT * returns columns in the order declared in the CREATE TABLE.

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NULL and COMPRESS

The default for all columns is NULLable and NOT compressible.

NULL column values are NOT automatically compressed.

COMPRESS compresses NULL column values to zero space.

COMPRESS compresses NULL and occurrences of to

zero space.

CREATE TABLE Employee

( emp_num INTEGER NOT NULL,dept_num INTEGER COMPRESS,

country CHAR(20) COMPRESS 'Australia',:

COMPRESS all fixed length columns where at least 10% of the rows

participate. COMPRESS creates smaller rows, therefore more rows/block and fewer

blocks.

You cannot use the COMPRESS option with:

Primary Index

Referenced and referencing data columns (PK-FK)

VARCHAR, VARBYTE, and VARGRAPHIC data types CHAR, BYTE, and GRAPHIC data types > 255 characters

How many bits are allocated?

01

2

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NOT NULL Clause

In relational systems, NULL means missing or unknown.

The default for all columns is NULLable.

Specify NOT NULL on the CREATE TABLE as appropriate:

All PRIMARY KEY columns

All UNIQUE columns

All columns with NN (No NULLS) constraints

Any index may contain NULLs unless explicitly prohibited.

NOT NULL permits storage of zero and blank values.

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Multi-Value Compression (V2R5 Feature)

What is Multi-Value Compression?

A V2R5 enhancement that allows up to 255 distinct values (plus NULL)to be

compressed per fixed width column a.k.a., Value List Compression.

Enhances system cost and performance of high data volume applications.

Provides significant performance improvement for general ad-hocworkloads and full-table scan applications.

Reduces storage cost by storing more logical data per unit of physical

capacity. Performance is improved because there is less physical data to

retrieve during scan-oriented queries.

Best candidate for compression - fixed width column with a small number

of frequently occurring values in large table used frequently for FTSs.

Compression in V2R4 provided up to 25% capacity savings and scan

performance increases up to 35%.

V2R5 Compression is expected to yield even greater savings.

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Rules for Compression

Up to 255 values (plus NULL) can be compressed per column.

The maximum size of a compress value remains 255 bytes.

Only fixed-width columns can be compressed.

Primary index columns cannot be compressed.

ALTER TABLE does not support compression on existing columns.

You can not add a compress value to a column if doing so would cause

the table header row to exceed its maximum length (64 KB).

Number of Presence Bits needed for Multi-Value Compression:

Compressed Values # of Bits

1 12 - 3 2

4 - 7 3

8 - 15 4

16 - 31 5

32 - 63 6

64 - 127 7

128 - 255 8

Note:

If column is "nullable",

there will be 1 additional

presence bit.

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Implementing Multi-Value Compression

ALTER TABLE accepts a list of values

for field attribute 'COMPRESS'.

Add a Education column.

ALTER TABLE People

ADD Education CHAR(10)COMPRESS

('ELEMENTARY',

'MIDDLE',

'HIGH',

'COLLEGE',

'POST GRAD') ;

CREATE TABLE accepts a list of values

for field attribute 'COMPRESS'.Compress the top 15 most populated

countries. Compress the Sex field.

CREATE TABLE People

( Name VARCHAR(100),Address VARCHAR(100),

Country CHAR(100) COMPRESS

( 'Australia', 'Bangladesh',

'Brazil', 'China', 'England',

'France', 'Germany', 'India',

'Indonesia', 'Japan', 'Mexico',

'Nigeria', 'Pakistan',

'Russian Federation',

'United States of America'

),

Sex CHAR(1) COMPRESS ('F', 'M')

);

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V2R5 Compression

Compression is not supported on the following data types:

INTERVAL TIME TIMESTAMP

VARCHAR VARBYTE VARGRAPHIC

Compression is supported on the following data types:

DATE (4) CHAR (N) (N

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ANSI and Teradata Data Types

Teradata ANSI (Core) equivalent

INTEGER INTEGER

SMALLINT SMALLINT

BYTEINT

DATE

TIME, TIME WITH TIME ZONE

TIMESTAMP, TIMESTAMP WITH TIME ZONE

FLOAT FLOAT

FLOAT REAL

FLOAT DOUBLE PRECISION

DECIMAL(n,m) DECIMAL(n,m)

DECIMAL(n,m) NUMERIC(n,m)

CHAR(n) CHAR(n)

VARCHAR(n), CHAR VARYING(n)

LONG VARCHAR

BYTE(n), VARBYTE(n)

GRAPHIC(n)VARGRAPHIC(n), LONG VARGRAPHIC

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Data Types

-128 to +127 Non-ANSI

S

I

G

N

BYTEINT

-32,768 to +32,767SMALLINT

S

I

G

N

-2,147,483,648 to +2,147,483,647INTEGER

S

I

G

N

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Data Types (Date and Time)

((YYYY - 1900)) * 10000 + (MM * 100) + DDDATE (4 Bytes)

TIME (6 Bytes) hh:mm:ss.ssssss

TIME WITH

TIME ZONE (8 Bytes) hh:mm:ss.ssssss +/- hh.mm

TIMESTAMP (10 Bytes) Date + Time

TIMESTAMP WITH

TIME ZONE (12 Bytes)

Date + Time + Zone

DATE, TIME, and TIMESTAMP are also SQL functions.

CURRENT_DATE, CURRENT_TIME, and CURRENT_TIMESTAMP represent

values.

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Data Types (Decimal, Numeric, Float, Real,

Double Precision)

Decimal and Numeric

DECIMAL [ ( n [ , m ] ) ]

n = 1 - 18

m = 0 - n

Default = (5, 0)

Stored in scaled binary

Number of Number of

Digits Bytes

1 to 2 1 byte

3 to 4 2 bytes

5 to 9 4 bytes

10 to 18 8 bytes

FLOAT, REAL, and DOUBLE PRECISION

Notes:

Range is 2 * 10 -307 to 2 * 10 +308

15 significant decimal digit precision.

Manipulated in IEEE floating point format.

Corresponds to, but is not identical to, IBM

normalized 64 bit floating point.

S

I

G

N

Exponent

11 Bits

Fraction/Mantissa

52 Bits

8 Bytes

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Data Types (BYTE and VARBYTE)

BYTE

Stored in host format.

Never translated by the Teradata Database

Handled as if they were n-byte, unsigned binary

integers.

Suitable for digitized image information

VARBYTE ( n ) n = 1 - 64000

Variable length binary string

2 byte column offset identifies location in row

2

BYTE ( n ) n = 1 - 64000

Fixed length binary string

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Data Types (GRAPHIC, VARGRAPHIC,

LONG VARGRAPHIC)

2 bytes per character.

Used for double-byte Kanji and Hiragana, and

Chinese double-byte Hanzi values.

VARGRAPHIC

GRAPHIC ( n ) n = 1 - 32000Fixed length multi-byte character string;

n is the length in logical characters.

VARGRAPHIC ( n ) n = 1 - 32000

Variable length multi-byte character

string; n is the length in logicalcharacters.


2

2LONG VARGRAPHIC

Equivalent to VARGRAPHIC (32000)


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Variable Column Offsets

50 75 75 100 c1 data c3 data

c1 c2 c3 x 5 7 10 5 0

0

Offset Array Variable Length Data

Offset values tell the starting location of a variable column.

Determine the column length by subtracting its starting location

from the next columns starting location.

The definition of variable length columns requires one additional 2-byte offset that locates the end of the final variable column.

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Sizing Considerations

Compress only columns where at least 10% to 20% of the rows participate.

COMPRESS will create smaller rows, and smaller rows are generally more

efficient.

Compress columns whose NULL values are not subject to changes.

Compression saves space but costs computational overhead.

Adding a column that is not compressible expands all rows.

Adding a column that is compressible and there are no spare presence bits

expands all rows.

Dropping a column changes all row sizes where data is present.

Use VARCHAR whenever the space savings offset the overhead.

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Example: Sizing a Row

SUPV JOB LAST FIRST HIRE BIRTH SALARY

EMP # EMP # DEPT # CODE NAME NAME DATE DATE AMOUNT

PK,SA FK FK FK NN NN NN NN NN

INT INT INT SMALL Char Char DATE DATE DECINT Fix 20 Var 30 (10,2)

EMPLOYEE

Using this logical row layout, the next page will size a typical row of the Employee table.

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Example: Completing the Row Size Calculation Form

Data Type # of Columns Size TOTAL

BYTEINT * 1 =SMALLINT 1 * 2 = 2

INTEGER 3 * 4 = 12

DATE 2 * 4 = 8

TIME(ANSI) * 6 =

TIME with ZONE * 8 =

TIMESTAMP * 10 =

TIMESTAMP/ ZONE * 12 =DECIMAL 1-2 * 1 =

3-4 * 2 =

5-9 * 4 =

10-18 1 * 8 = 8

FLOAT * 8 =

Fixed 1 SUM(n) = 20

Variable 1 SUM(a) = 14LOGICAL SIZE = 64

Overhead = 14

Partitioned Primary Index Overhead (2) = 0

Variable Column Offsets(_1_ * 2 ) + 2 ; zero if no variable columns = 4

___0__ Bits for Compressible Columns

___3__ Nullable Columns

___3__ / 8 (Quotient only) = 0PHYSICAL ROW SIZE = 82

Table Name EMPLOYEE

Column Name Type Max Average

First Name CV 30 14

SUM(a) = 14

Variable Column Data Detail

SUM(a) = SUM of the AVERAGE number of bytes

expected for the variable column.

SUM(n) = SUM of the CHAR and GRAPHIC column

bytes.

** For V2, round up to an even number of bytes.

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Row Size Calculation Form


BYTEINT * 1 =SMALLINT * 2 =

INTEGER * 4 =

DATE * 4 =

TIME(ANSI) * 6 =


TIMESTAMP * 10 =


3-4 * 2 =

5-9 * 4 =

10-18 * 8 =

FLOAT * 8 =

Fixed SUM(n) =

Variable SUM(a) =

LOGICAL SIZE =

Overhead = 14

Partitioned Primary Index Overhead (2) =

Variable Column Offsets(__ * 2 ) + 2 ; zero if no variable columns =

_____ Bits for Compressible Columns

_____ Nullable Columns

_____ / 8 (Quotient only) =PHYSICAL ROW SIZE =

Table Name ____________________


SUM(a) =





bytes.


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Row Size Exercise

CALL

CALL

NUMBER

PK, SA

TAKEN BY

EMPLOYEE

NUMBER

CUSTOMER

NUMBER

FK, NN FK

PLACED BY

CONTACT

NUMBER

FK

PLACED BY

EMPLOYEE

NUMBER

FK

ORIGINAL

CALL

NUMBER

FK

UPI NUSI

CALL

DATE

NN

NUSI

SYSTEM

CATEGORY

PART

NUMBER

CALL

TIME

NN

CALL

STATUS

CODE

FK, NN

CALL

TYPE

CODE

FK, NN

CALL

PRIORITY

CODE

FK, NN

NUSINUSI

FK FK

AREA

CODE PHONE EXTENSION

100 100

DOMAIN

NAME

Call_Number

Employee_Number

Customer_Number

Contact_Number

Date

Time

Call_Status_Code

Call_Type_Code

Call_Priority_Code

Area_Code

Phone

Extension

System_Number

Part_Category

MAX

BYTES

4

4

4

4

4

6

2

2

2

2

4

4

4

4

DATA

TYPE

INT

INT

INT

INT

D

TIME

CF

SMALL INT

INT

INT

INT

INT

SMALL INT

SMALL INT

Example ofConstraint Number

This table will be partitioned via RANGE_N on Call_Date with Monthly intervals.

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Row Size Calculation Form


BYTEINT * 1 =SMALLINT * 2 =

INTEGER * 4 =

DATE * 4 =

TIME(ANSI) * 6 =


TIMESTAMP * 10 =


3-4 * 2 =

5-9 * 4 =

10-18 * 8 =

FLOAT * 8 =

Fixed SUM(n) =

Variable SUM(a) =

LOGICAL SIZE =

Overhead = 14

Partitioned Primary Index Overhead (2) =

Variable Column Offsets(___ * 2 ) + 2 ; zero if no variable columns =

______ Bits for Compressible Columns

______ Nullable Columns

______ / 8 (Quotient only) =PHYSICAL ROW SIZE =

Table Name CALL


SUM(a) =





bytes.


3 6

10 40

1 4

1 6

1 2

0

58

2

9

9 +175 76

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Table Headers

One row per AMP per Table.

Table headers are a separate subtable.

Minimum table header block size is 512

bytes (1 sector) per AMP.

Typically, a table header will be at least

1024 bytes. For example:

Tables with 4 or more columns

Tables with 2 columns and a NUSI

Compressed values are maintained

within the table header.

Multiple values that are compressedfor a column are maintained in an

array in the table header.

Maximum value of approximately 64K.

The base table header covers all of its

secondary index subtables.

STANDARD ROW HEADERLENGTH, ROW ID, PRESENCE/SPARE BYTES

FIELD 2 OFFSETFIELD 3 OFFSET

FIELD 4 OFFSET

FIELD 5 OFFSET

FIELD 6 OFFSET

FIELD 7 OFFSET

FIELD 8 OFFSET

FIELD 9 OFFSET

EXTRA OFFSET

DATABASE AND TABLENAMES

DATABASE ID

OTHER INTERNAL INFOCREATION DATE, PROTECTION, TYPE OFJOURNALING, JOURNAL ID, STRUCTVERSION, etc.

FIELD

1

INDEX DESCRIPTORS(36 BYTES * # INDEXES) PLUS 20 BYTESPER INDEX COLUMN

F2

ALWAYS NULL 3

FASTLOAD & RESTOREINFORMATION

USUALLY NULL

F4

BASE COLUMN INFOCOUNT OF COLUMNS, LOCATION OF FIRSTFIXED FIELD, NUMBER OF PRESENCE BITS,etc. 24 BYTES

COLUMN INFORMATION FOREACH COLUMN

20 BYTES PER COLUMN(+ COMPRESS VALUE)DATA TYPE, OFFSET WITHIN ROWNULLIBLE/NOT NULLIBLE, COMPRESS/NOCOMPRESS, PRESENCE BIT LOCATION, etc.

FIEL

D

5

RESTARTABLE SORTINFORMATION

USUALLY NULL

F

6

ALWAYS NULL 7

ALWAYS NULL 8

ALWAYS NULL 9

ROW LENGTH orREF. ARRAY POINTER

V2R4 Example of Table Header

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Sizing a Data Table

Block sizes vary within a table, so compute a range.

Typically, the maximum block size is 63.5 KB bytes, and a typical block size is 48 KB.

Formula:

(BlockSize - 38) / RowSize = RowsPerBlock (rounded down)

RowCount / RowsPerBlock = Blocks (rounded up)

NumAmps * 1024 = Header(Blocks * BlockSize) + Header = NO FALLBACK (BlockSize = Typical Block Size)

(Blocks * BlockSize) * 2 + Header = FALLBACK (BlockSize = Typical Block Size)

Parameters:

38 = Block Header + Block Trailer BlockSize = Typical block size in bytes

1024 = Typical table header size NumAmps = Number of AMPs in the systemRowCount = Number of table rows expected

RowSize = Physical row size

Note:

For large tables, table headers and block overhead (38 bytes) add a minimal

amount of size to the table. Therefore, multiply row size by number of rows

and double for Fallback.

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Table Sizing Exercise

Given this data, estimate the size of a table with Fallback and a typical block size of 48K.

BlockSize = 49,152 bytes (48K) NumAmps = 20

RowCount = 501,000,000

RowSize = 98 bytes (includes overhead)

Formula: (BlockSize - 38) / RowSize = RowsPerBlock (round down)

RowCount / RowsPerBlock = Blocks (round up)

NumAmps * 1024 = Header

(Blocks * BlockSize) + Header = No Fallback

(Blocks * BlockSize) * 2 + Header = Fallback

Calculation:

(49,152 - 38) / 98 = 501 rows per block501,000,000 / 501 = 1,000,000 blocks

20 * 1024 = 20,480 for table headers

(1,000,000 * 49,152) + 20,480 = 49,152,020,480 (No Fallback)

(1,000,000 * 49,152) * 2 + 20,480 = 98,304,020,480 (Fallback)

An easier way to estimate this table size:501,000,000 x 98 bytes x 2 (Fallback) = 98,196,000,000

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Estimating the Size of a USI Subtable

Spare &

Presence

Row

Length

Row ID of USI

Row

Hash

Uniq.

Value

Secondary

IndexValue

Base Table RowIdentifier Ref.

ArrayPointer

2 4 4 2 7 Variable 2 (opt.) 4 4 2Bytes

Row Offsets

& Misc. (>=7)

Row

Hash

Uniq.

ValuePart.

#

There is one Index row for each Base Table row.USI subtable row size = (Index value size + 29 or 31)

Where 31 = 4 (Row Header and Row Ref. Array pointer)

+ 8 (This row's Row ID)

+ 9 (Spare, presence, and offset bytes)

+ 2 (Optional Partition # for PPI tables)

+ 8 (Base table Row ID)

To estimate the amount of space needed for a USI subtable, you can use the

following formulas.

For tables with NPPI, USI Subtable Size = (Row count) * (index value size + 29)

For tables with PPI, USI Subtable Size = (Row count) * (index value size + 31)

Note: Double this figure for Fallback.

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Estimating the Size of a NUSI Subtable

Row Offsets

& Misc. (>=7)

Spare &

Presence

Row

Length

Row ID of NUSI

RowHash

Uniq.Value

Secondary

Index

Value

Ref.

Array

Pointer

2 4 4 2 7 Variable 8/10 8/10 2Bytes

Table Row ID List

P RH U

2 4 4

P RH U

2 4 4

There is at least one index row per AMP for each distinct index value that is in the base table

on that AMP.

To estimate the size of a NUSI subtable,

Size = (Row count) * 8 (or 10 for PPI tables)

+ ( (#distinct values) * (Index value size + 21) * MIN ( #AMPs, Rows per value ) )

MIN( ___ , ___ ) use the smaller of the two values.

Double this figure for Fallback.

More AMPs than typical rows/value:

(10 AMPS, 5 rows/value)

NOT Every AMP has every value.

NOT Every AMP has a subtable row for every value.

More strongly selective. Fewer rows returned from an equality search.

Example:

More typical rows/value than AMPS:

(50 rows/value, 10 AMPS)

Every AMP probably has every value.

Every AMP has a subtable row for every value.

More weakly selective. More rows returned from an equality search.

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Estimating the Size

of a Reference Index Subtable

Row OffsetsOverhead

Row

Length

Row ID of RI

Row

Hash

Uniq.

Value

Foreign

KeyValue

Ref.

ArrayPointer

2 4 4 2 6 1 0+ Variable 4 2Bytes

Valid

Flag Count

Optional Presence and

variable length indicators

There is one reference index row for each distinct foreign key value.

RI subtable row size = (Index value size + 25)

Where 25 = 4 (Row Header and Row Ref. Array pointer)

+ 8 (This row's Row ID)

+ 8 (Overhead and row offset bytes)

+ 1 (Validity flag)

+ 4 (Count)

To estimate the size of a Reference Index (RI) subtable, you can use the

following formula.

RI Subtable Size = (Distinct count) * (index size + 25)

Double this figure for Fallback.

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Index Sizing Exercise

A 1,000,000 row Fallback table, on a 20-AMP system, has an Integer USI and a

50 Row per Value CHAR(29) NUSI with 20,000 distinct values.

Assume the table is partitioned. Estimate the space for each secondary index.

Formulas:

USI Size = Row Count * (IndexValueSize + 31)

NUSI Size = (Row Count * 10)

+

(#distinct values) * (Index value size + 21) * MIN ( #AMPs , Rows per value )

1,000,000 * (4 + 31 + 1) * 2 = 72,000,000

(10,000,000 + (20,000 * (29 + 21) * 20)) * 2 = 60,000,000

Note: +1 - Rows are allocated on even offsets within the data block.

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Empirical Sizing

The best way to size a production table, including indexes is:

1. Load a known percentage of rows onto the system.

2. Query the DD through the view DBC.TableSize.

3. Create one index.

4. Query the DD through the view DBC.TableSize.

5. Repeat steps 3 and 4 as necessary.

6. Multiply the results to determine the production size.

Example:

Step 1 Load 1% of a table onto a system.

Step 2 SELECT SUM(CurrentPerm) FROM DBC.Tablesize

WHERE DatabaseName = DATABASE

AND TableName = 'Daily_Sales' ;

Sum(CurrentPerm)

671,744Step 3 CREATE INDEX (sales_date) ON Daily_Sales;

Step 4 SELECT SUM(CurrentPerm) FROM DBC.Tablesize


AND TableName = 'Daily_Sales' ;

Sum(CurrentPerm)914,944

Therefore, index size is:

914,944

671,744243,200

Note: The same query

without the SUM

keyword returns

per/AMP figures which

reveal distribution

efficiency.

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Spool Space

Maximum spool space needs vary with table size, use (type of application),

and frequency of use. Large systems use more spool to duplicate tables on each AMP.

Cylinders not currently used for data may be used for spool.

The user's spool amount may be changed dynamically.

Avoid unnecessary copying or redistribution of entire tables to spool.

As user con currency and/or SQL complexi ty inc reases, add mo re SPOOL.

Running out of Spool Space

If a user exceeds their Spool space limit, they will receive the following errormessage.

2646 No more spool space in username

If the AMP runs out of Spool space (insufficient available cylinders for Spool),

the following message will be displayed.

2507 - Out of spool space on disk

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Release of Spool

Intermediate Spool

Intermediate Spool results are held until the (LastUse) Explain step.

Output Spool

Output Spool results are held until:

Last spool Response - BTEQ

CLOSE cursor - PreProcessor

ERQ, Terminate function - CLI

Session ends (Job Abort, timeout, logoff, etc.)

System is restarted

System Restart - each AMP rebuilds its Master Index from its Cylinder

Indexes.

The AMPs delete all spool files by moving them to the Free Cylinder List.

This costs only one I/O per spool cylinder, and saves maintaining the

Master Index on disk.

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System Sizing Exercise

Some general guidelines for estimating system size:

20% (or more) of total space for Spool5% of total space for PJs/development/staging

5% of total space for DBC & Transient Journal

20 - 50% of data size for indexes

If not using Fallback, multiply the amount of raw data by a factor of 2 or 3.

If using Fallback, multiply the amount of raw data by a factor of 4 or 5.

Example:

User raw data 400 GB

Estimate of Vdisk space needed 1600 - 2000 GB

Proof:

Estimate of Vdisk space 1600 - 2000 GB- Spool (20%) - 400 GB

- PJs/development/staging (5%) - 100 GB

- DBC & Transient Journal (5%) - 100 GB

1000 - 1400 GB

User raw data 400 GB

20 - 50% for indexes 80 - 200 GBFallback (for data and indexes) 960 - 1200 GB

A 4 node system, each

with 7 AMPs, and each

AMP with 72 GB of Vdiskspace would meet this

requirement.

4 x 7 x 72 GB = 2016 GB

of available space

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Sizing Summary

Accurate row counts and sizes are needed to get good space estimates.

Database sizing includes:

Tables + Fallback +

Secondary Indexes + Fallback +

Reference Indexes + Fallback +

Join Indexes + Fallback +

Hash Indexes + Fallback +

Permanent Journal (dual or single) +

Stored Procedure space +Spool space +

Temporary space

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Review Questions

1. Which of the following can be used with the COMPRESS option?

a. Referencing columns - Foreign Key

b. Referenced column - Primary Key as a USIc. Unique Primary Index

d. Non-unique Secondary Index

2. Which section of a row identifies the starting location of variable length data column data and is

present only if variable length columns are declared?

a. Uncompressed Columns

b. VARCHAR Columns

c. Presence Bits

d. Column Offsets

3. How can you override the default that a column with a NULL value will require row space?

a. Use the COMPRESS option on the column as part of the CREATE TABLE statement.

b. When creating the user, set the default so that columns will default to COMPRESS when creating

a table.

c. Use the NOT NULL option on the column as part of the CREATE TABLE statementd. Use the DEFAULT NULL option on the column as part of the CREATE TABLE statement.

4. What is the minimum space the table headers will take for a 6-column table on a 10 AMP system?

a. 10240 bytes

b. 4096 bytes

c. 5120 bytes

d. 1024 bytes

5. What DD view can you query to get sizing information about tables? _____________________

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Module 10: Review Question Answers

1. Which of the following can be used with the COMPRESS option?

a. Referencing columns - Foreign Key

b. Referenced column - Primary Key as a USIc. Unique Primary Index

d. Non-unique Secondary Index

2. Which section of a row identifies the starting location of variable length data column data and is

present only if variable length columns are declared?

a. Uncompressed Columns

b. VARCHAR Columns

c. Presence Bits

d. Column Offsets

3. How can you override the default that a column with a NULL value will require row space?

a. Use the COMPRESS option on the column as part of the CREATE TABLE statement.

b. When creating the user, set the default so that columns will default to COMPRESS when creating

a table.

c. Use the NOT NULL option on the column as part of the CREATE TABLE statementd. Use the DEFAULT NULL option on the column as part of the CREATE TABLE statement.

4. What is the minimum space the table headers will take for a 6-column table on a 10 AMP system?

a. 10240 bytes

b. 4096 bytes

c. 5120 bytes

d. 1024 bytes

5. What DD view can you query to get sizing information about tables? DBC.Tablesize

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Lab Exercises

Lab Exercise 10-1

PurposeIn this lab, you will compress multiple values for a column in order to reduce Perm space.

What you need

Populated AU.Accounts table and an empty table in your database

Tasks

1. Populate your Accounts table from the AU.Accounts table using the INSERT/SELECT statement:

INSERT INTO Accounts SELECT * FROM AU.Accounts;

Using the DBC.TableSize view, what is the amount of Perm space used. Accounts =___________

2. Create a new table, named "Accounts_MVC", based on the Accounts table except compress the

following city names:

Culver City, Hermosa Beach, Los Angeles, and Santa Monica

Populate your Accounts_MVC table from the AU.Accounts table using INSERT/SELECT.

Using the DBC.TableSize view, what is the amount of Perm space used. Accounts_MVC =___________

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Lab Exercises

Lab Exercise 10-2

PurposeIn this lab, you will use populate tables, determine tables sizes, and create secondary indexes.

What you need

Populated AU.Trans table and an empty table in your database

Tasks

1. Determine the size of your empty Trans table using the DBC.TableSize view (SELECT with and withoutthe SUM aggregate function).

Size of empty Trans = _______________

What size are the table headers on each AMP? _______________

2. Using SHOW TABLE, the Row Size Calculation form and the Sizing a Data Table Formula, estimate

the size of this table; assume 15,000 rows.

Estimated size of Trans = _______________

3. Populate your Trans table from the AU.Trans table using the following INSERT/SELECT statement:

INSERT INTO Trans SELECT * FROM AU.TRANS;

Use the SELECT COUNT(*) function to verify the number of rows. ___________

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Lab Exercises

Lab Exercise 10-2 (cont.)

Tasks

4. Using the DBC.TableSize view, determine the actual size of the Trans table by using the SUM aggregate

function.

Size of populated Trans = _______________

5. Create a USI on the Trans_Number column.

Estimate the size of the USI = _______________

Actual size of the USI = _______________ (use the empirical sizing technique)

6. Create a NUSI on the Trans_ID column.

Estimate the size of the NUSI = ______________ (Hint: use DISTINCT function)Actual size of the NUS I= ______________ (use the empirical sizing technique)

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Lab Exercises

Lab Exercise 10-3

PurposeIn this lab, you will determine tables sizes and establish referential integrity between two tables.

What you need

Populated PD tables and empty tables in your database

Tasks

1. Populate your Employee and Emp_Phone tables from the PD.Employee and PD.Emp_Phone tablesusing the following INSERT/SELECT statements.

INSERT INTO Employee SELECT * FROM PD.Employee;

INSERT INTO Emp_Phone SELECT * FROM PD.Emp_Phone;

2. Using the DBC.TableSize view, determine the actual size of the Emp_Phone table by using the SUM

aggregate function.

Size of populated Emp_Phone table = _______________

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Lab Exercises


Tasks

3. The Foreign key is Employee_Number in PD.Emp_Phone and the Primary Key is the

Employee_Number in PD.Employee.

Create a References constraint on Employee_Number using the following SQL statements.

ALTER TABLE Emp_Phone ADD CONSTRAINT fk1

FOREIGN KEY (Employee_Number)

REFERENCES Employee (Employee_Number);

(use the HELP CONSTRAINT Emp_Phone.fk1; to view constraint information.

4. Using the DBC.TableSize view, determine the actual size of the Emp_Phone table by using the SUM

aggregate function.

Estimate the size of the Reference Index = _______________

Size of populated Emp_Phone with references index = _______________

Size of references index = _______________

5. Drop the Foreign Key constraint by executing the following SQL command.

ALTER TABLE Emp_Phone DROP CONSTRAINT fk1;

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Lab Solutions for Lab 10-1

Lab Exercise 10-1

1. Populate your Accounts table from the AU.Accounts table using the INSERT/SELECT statement:

INSERT INTO Accounts SELECT * FROM AU.Accounts;

Using the DBC.TableSize view, what is the amount of Perm space used. Accounts = 1,804,288

2. Create a new table, named "Accounts_MVC", based on the Accounts table except compress the

following city names: Culver City, Hermosa Beach, Los Angeles, and Santa Monica

CREATE SET TABLE Accounts_MVC, FALLBACK,

NO BEFORE JOURNAL, NO AFTER JOURNAL

(ACCOUNT_NUMBER INTEGER NOT NULL,

NUMBER INTEGER,

STREET CHAR(25),

CITY CHAR(20) COMPRESS ('Hermosa Beach', 'Culver City', 'Los Angeles','Santa Monica'),

STATE CHAR(2),ZIP_CODE INTEGER,

BALANCE_FORWARD DECIMAL(10,2),

BALANCE_CURRENT DECIMAL(10,2))

PRIMARY INDEX ( ACCOUNT_NUMBER );

Populate your Accounts_MVC table from the AU.Accounts table using INSERT/SELECT.

Using the DBC.TableSize view, what is the amount of Perm space used. Accounts_MVC = 1,404,828

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Lab Exercise 10-2

1. Determine the size of your empty Trans table using the DBC.Tablesize view (SELECT with and without the SUMaggregate function).

SELECT SUM(CurrentPerm) FROM DBC.Tablesize

WHERE DatabaseName = DATABASE AND TableName = 'Trans' ;

Sum(CurrentPerm)

8192 Size of empty Trans = 8192 (Captured from an 8 AMP system)

What size are the table headers on each AMP? 1024

2. Using SHOW TABLE, the Row Size Calculation form and the Sizing a Data Table Formula, estimate the size of this

table; assume 15,000 rows.

Each row is 24 bytes long plus 14 bytes for overhead = 38 bytes

38 x 15,000 = 570,000 x 2 (Fallback) = 1,140,000 bytes approx.

Estimated size of Trans = 1,140,000

3. Populate your Trans table from the AU.Trans table using the following INSERT/SELECT statement:

INSERT INTO Trans SELECT * FROM AU.TRANS;

Use the SELECT COUNT(*) function to verify the number of rows. 15,000

SELECT COUNT(*) FROM Trans; Count(*)15000

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Lab Solutions for Lab 10-2 (cont.)

Lab Exercise 10-2 (cont.)4. Using the DBC.Tablesize view, determine the actual size of the Trans table by using the SUM aggregate function.

Size of populated Trans = 1,153,024



AND TableName = 'Trans' ;

Sum(CurrentPerm)

1153024 (Estimated size was 1,140,000)

5. Create a USI on the Trans_Number column.

CREATE UNIQUE INDEX (Trans_Number) on Trans;

Estimate the size of the USI = 960,000

(4 + 29) x 15,000 = 480,000 x 2 (Fallback) = 990,000 bytes approx.

Actual size of the USI = 1,026,048 (use the empirical sizing technique)




Sum(CurrentPerm)2179072 2,179,072 - 1,153,024 = 1,026,048

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Lab Exercise 10-2 (cont.)6. Create a NUSI on the Trans_ID column.

CREATE INDEX (Trans_ID) on Trans;

Estimate the size of the NUSI = _______________

SELECT COUNT(DISTINCT(Trans_ID)) FROM Trans;

Count(Distinct(TRANS_ID))975

(15,000 x 8) + ( 975 x (4 + 21) x 8 ) = 315,000 bytes approx.

315,000 x 2 (Fallback) = 630,400 bytes approx.

Actual size of the NUSI = 523,264 (use the empirical sizing technique)




Sum(CurrentPerm)

2702336 2,702,336 - 2,179,072 = 523,264

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Lab Exercise 10-31. Populate your Employee and Emp_Phone tables from the PD.Employee and PD.Emp_Phone tables using the following

INSERT/SELECT statement:

INSERT INTO Employee SELECT * FROM PD.Employee;

INSERT INTO Emp_Phone SELECT * FROM PD.Emp_Phone;

2. Using the DBC.Tablesize view, determine the actual size of the Emp_Phone table by using the SUM aggregate function.

Size of populated Emp_Phone = 124,928

SELECT SUM (CurrentPerm) FROM DBC.Tablesize


AND TableName = 'Emp_Phone' ; Sum(CurrentPerm)

124,928

3. The Foreign key is Employee_Number in the Emp_Phone table and the Primary Key is the Employee_Number in the

Employee table.

Create a References constraint on Employee_Number using the following SQL statements.

ALTER TABLE Emp_Phone ADD CONSTRAINT fk1 FOREIGN KEY (Employee_Number)

REFERENCES Employee (Employee_Number);

(use the HELP CONSTRAINT Emp_Phone.fk1; to view constraint information.

HELP CONSTRAINT Emp_Phone.fk1;

Name Type State Index ID Foreign Key Columns ...FK1 REFERENCE VALID 0 EMPLOYEE_NUMBER ...

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4. Using the DBC.Tablesize view, determine the actual size of the Emp_Phone table by using the SUM aggregate function.

SELECT COUNT(DISTINCT(Employee_Number)) AS "Count"

FROM Emp_Phone;

Count

1000

(4 + 25) x 1,000 = 29,000 x 2 (Fallback) = 58,000 bytes approx.

Estimate the size of the Reference Index = 58,000

Size of populated Emp_Phone with references index = 190,464

SELECT SUM (CurrentPerm) FROM DBC.Tablesize


AND TableName = 'Emp_Phone' ;

Sum(CurrentPerm)

190464 190,464 - 124,928 = 65,536

Size of references index = 65,536

5. Drop the Foreign Key constraint by executing the following SQL command.

B210 Sizing

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