Fix: Add ENUM and TIMESTAMP support to histogram generation

[YoungHypo]

Pull Request Summary

This PR adds proper handling for ENUM and TIMESTAMP data types in the Videx histogram module, addressing issues where these types were not correctly processed during histogram bucket generation and selectivity calculation.

Related Issues

Resolves: #55

Changes Made

1. Type Conversion (convert_str_by_type):

   • Added enum to string-type handling list
   • Added timestamp to datetime-type handling list

2. Histogram Position Calculation (find_nearest_key_pos):

   • Extended string comparison logic to support enum types
   • Extended datetime offset calculation to support timestamp types

3. SQL Value Formatting (_format_value_by_type_in_sql):

   • Added ENUM handling (format with quotes and escape)
   • Added TIMESTAMP handling (format with quotes)

4. Bucket Boundary Generation (_get_uniform_buckets):

   • Added ENUM and TIMESTAMP to sampling-based boundary generation

How to test ENUM and TIMESTAMP

generate_bulk_data_simple.py

source_schema_simple.sql

1.generate testing data

python3 generate_bulk_data_simple.py

2. import data to database

mysql -h 127.0.0.1 -u root -p < source_schema_simple.sql
mysql -h 127.0.0.1 -u root -p < bulk_insert_data.sql

3. start videx_server and collect data

4. test timestamp

mysql -h127.0.0.1 -P13308 -uvidex -ppassword
USE videx_ddw_test_src;
EXPLAIN SELECT * FROM orders WHERE created_at >= '2025-01-01 00:00:00' AND created_at < '2025-04-01 00:00:00';

5. test enum (haven't fixed)

However, there are still some issues with the ENUM tests. For example, both the user and product tables contain an ENUM column named status, but while the user query returns rows correctly, the query on product.status fails.

More Results

You can see more execution results of explain sqls from innodb_sql.test and videx_sql

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