Minimize Dynamic Fields in Objects

[mvandeberg]

Dynamic fields in objects are costly because when moving between undo states, those objects are copied and have to use the memory mapped file memory allocator.

This is not a huge concern when reindexing because we do not use undo states, but when live an syncing, this can be a huge cost. (On appbase steemdsync we are averaging 1.9 blocks/sec syncing the most recent 10k blocks)

Plugins, on the other hand, do utilize undo states for custom ops because bad ops cannot be rejected by the blockchain.

Below are all objects with dynamic fields. For each dynamic field we should provide justification for the field and, if possible, refactor the objects such that dynamic fields do not live in objects that have frequent modifications. This requires moving either dynamic or hot data out of the object in question

Consensus:

__account_object:__

• json_metadata

account_authority_object:

• owner
• active
• posting

__owner_authority_history_object:__

• previous_owner_authority

__account_recovery_request_object:__

• new_owner_authority

__comment_object:__

• category
• parent_permlink
• permlink
• beneficiaries

comment_content_object:

• title
• body
• json_metadata

hardfork_property_object:

• processed_hardforks

__history_object:__

• serialized_op

savings_withdraw_object:

• memo

feed_history_object:

• price_history

__transaction_object:__

• packed_trx

__witness_object:__

• url

Follow Plugin:

__feed_object:__

• reblogged_by

[mvandeberg]

As much as the comment implies the by_parent index on comment objects is consensus, it does not appear so which means that parent_author and parent_permlink can be replaces by comment_id_type parent.

Such a refactor directly impacts the efficacy of #1595