Event driven database

Add new bytes32 data member to PheixAccess event at PheixDatabase smart contract.

The idea is to use that new event topic to store data directly on blockchain via built-in Ethereum event mechanism. Consider insert or update: these functions store data via mappings and other solidity-driven features. The data is actually a |-separated string like:

0xd67495f282530196a6db3441ce39eaac06faf22f|aqicn-32|Mon, 22 Jul 2024 12:36:12 GMT|ewogICJlbnJpY2htZW50IjogewogICAgInRpdGxlIjogInBhcmsgSW0uIEEuQm90YWxpZXZhIiwKICAgICJwcm9maWxlIjogImh0dHBzOi8vYXFpY24ub3JnL3N0YXRpb24vQDM5ODA3Ny8iLAogICAgInBvc2l0aW9uIjogewogICAgICAibG5nIjogNzQuNTg1NjkyOCwKICAgICAgImxhdCI6IDQyLjkwNjk0NzIKICAgIH0KICB9LAogICJzZW5zb3JkZXZpY2UiOiAiRXRoZWxpYTo6U3RhdGlvblBhcnNlcjo6QVFJQ04iLAogICJzZW5zb3J2YWx1ZSI6ICI0MyIKfQ==|parkImABotalieva

That string is stored in mapping with the specific metadata: id and compression flag, which we can also store in event:

event PheixAccess (
    uint8   indexed mcode,
    bytes32 indexed table,
    uint256 indexed rowid,
    bytes32         data,
    uint8           compression,
);

Open points / To be discussed

How to perform delete/remove functions on event

Just add indexed zombie member of uint8 type — if it's set to 1: it means the deleted record and we should not include it in the full table representation.

How to collect full table from event list

By table and zombie members — table should contain searched table name and zombie should not set to 0.