vbnet

SET HEADING ON
SET MARKUP CSV ON
SPOOL data_export.csv
SELECT * FROM your_table;
SPOOL OFF


• Examine your Oracle schema and decide how each data type will map into DuckDB.
• For example, use INTEGER or BIGINT for integer columns, DECIMAL(p, s) for numeric columns with precision, TIMESTAMP for date-time columns, and VARCHAR for text.
• If Oracle’s DATE columns include time data, define them as TIMESTAMP in DuckDB to avoid losing the time portion.
• Create the tables. For instance:

CREATE TABLE new_table (
   column1 INTEGER,
   column2 VARCHAR,
   column3 TIMESTAMP
);


• Run the DuckDB CLI or use a script to load each CSV into its corresponding table.
• A common syntax is:

COPY new_table
FROM 'path/to/data_export.csv'
(AUTO_DETECT TRUE);


• Consider these points:
  • If auto-detection fails, specify options like DELIMITER ',', HEADER TRUE, or DATEFORMAT '%Y-%m-%d'.
  • Ensure text and numeric columns match the table’s data types to avoid errors.
  • If some rows contain invalid data for the target column type, fix those rows in the CSV or adjust the schema as needed.

• If needed, convert columns that imported as text into the right data type. For example:

UPDATE new_table
SET date_column = STRPTIME(date_column, '%d-%b-%y');


• Check any columns that in Oracle might have been empty strings but now appear as actual empty strings instead of NULL. Update them if your application needs them to be NULL:

UPDATE new_table
SET text_column = NULL
WHERE text_column = '';


• Align numeric columns if Oracle used a precision larger than what you defined in DuckDB.

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Add Indexes and Constraints

• Align your new DuckDB tables with the constraints in Oracle. For instance:

ALTER TABLE new_table
ADD PRIMARY KEY (id_column);


• If you need unique constraints or foreign keys, add them similarly:

ALTER TABLE child_table
ADD FOREIGN KEY (fk_column) REFERENCES parent_table(pk_column);


• DuckDB often runs analytical queries quickly without many indexes, but if you have frequent point lookups, consider adding them using:

pgsql

CREATE INDEX idx_name ON new_table(column1);


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