What's the best way to calculate table usage in Mb?

Question

Given a table structure, and knowing it will receive 30.000 new entries on each month, how do I calculate the table growth in kb?
Also, how can I calculate initial disk ocupation from the table?
Is there an equation or formula that I can apply using column definition as params?
That's one of the tables on my application I have to calculate:
CREATE TABLE "LOG_PESQUISA"
(     "COD_LOG_PESQUISA" NUMBER(10,0) NOT NULL ENABLE,
     "TXT_PCHAVE" VARCHAR2(100),
     "IND_DIGITAL" NUMBER(1,0) NOT NULL ENABLE,
     "VLR_TOTALFISICO" NUMBER(9,0) NOT NULL ENABLE,
     "VLR_TOTALDIGITAL" NUMBER(9,0) NOT NULL ENABLE,
     "IND_FISICO" NUMBER(1,0) NOT NULL ENABLE,
     "TXT_CODIGO" VARCHAR2(50),
     "TXT_BOOLEAN_TYPE" VARCHAR2(3),
     "IND_DATA" NUMBER(1,0) NOT NULL ENABLE,
     "DAT_INI" DATE,
     "DAT_FIM" DATE,
     "COD_COLECAO" NUMBER(10,0),
     "COD_CREDITO" NUMBER(10,0),
     "VLR_EDICAO" NUMBER(5,0),
     "IND_TAMANHO" VARCHAR2(2),
     "IND_PUBLICADAS" NUMBER(1,0) NOT NULL ENABLE,
     "IND_SOBRAS" NUMBER(1,0) NOT NULL ENABLE,
     "IND_LUI" NUMBER(1,0) NOT NULL ENABLE,
     "IND_AUI" NUMBER(1,0) NOT NULL ENABLE,
     "COD_USU_INC" VARCHAR2(30) NOT NULL ENABLE,
     "DAT_INC" DATE NOT NULL ENABLE,
     "ID_CREDITO" NUMBER(10,0),
     "IND_PCHAVE" NUMBER(1,0) NOT NULL ENABLE,
     "IND_HEADLINE" NUMBER(1,0) NOT NULL ENABLE,
     "IND_LEGENDA" NUMBER(1,0) NOT NULL ENABLE,
     CONSTRAINT "LOG_PESQUISA_PESQUISA_PK" PRIMARY KEY ("COD_LOG_PESQUISA") ENABLE
/

Answer 1

The most accurate approach would be to
1) Create the table
2) Load it with some sample data. Make sure that the sample data is as close to reality as possible (i.e. if txt_pchave will be 90 characters 20% of the time, 50 characters 50% of the time, 10 characters 20% of the time and NULL 10% of the time, make sure your sample data reflects that).
3) Query DBA_SEGMENTS to see how big the table is
SELECT segment_name table_name, sum(bytes)/1024/1024 MB
  FROM dba_segments
WHERE segment_name = 'LOG_PESQUISA'4) Multiply by the number of rows that you really expect. You might load 3,000 records in step 2, for example, so you'd multiply by 10 to get the size if you loaded 30,000 records.
You can extend this to look at the size of the index(es) relatively easily. If you are doing more than straight inserts, you would also want to simulate that to account for things like row migration, empty blocks, etc.
Justin