Update DB layer to use COPY to insert into history tables

[tamirms]

Currently, we use the BatchInsertBuilder to batch history table rows into large Postgres INSERT statements. However, we have discovered that it is more efficient to use the Postgres COPY statement for bulk loading. Note that COPY does not provide support for updating existing rows but that is ok because the Horizon history tables are immutable (rows are only inserted and never updated).

To complete this issue we will need to:

• Implement a component similar to BatchInsertBuilder which uses COPY instead of INSERT (feel free to use the prototype from the spike)
  • The unit tests for this component should check that the transaction can still be rolled back if an error is encountered before stmt.Close() (this should address bartek's concerns from Ingestion performance fixes #316 (comment) )
• Once the component is implemented we will need to integrate it in all the services/horizon/internal/db2/history code which inserts rows into the history tables (see master...tamirms:go:ingest-perf-pq for how this is done in the spike branch). After this task is complete the following tables will be populated by the COPY batch insert builder:
  • history_effects
  • history_ledgers
  • history_operation_claimable_balances
  • history_operation_liquidity_pools
  • history_operation_participants
  • history_operations
  • history_trades
  • history_transaction_claimable_balances
  • history_transaction_liquidity_pools
  • history_transaction_participants
  • history_transactions

[urvisavla]

Note that COPY does not provide support for updating existing rows but that is ok because the Horizon history tables are immutable (rows are only inserted and never updated).

@tamirms, What happens during reingestion of a ledger range? I understand that it updates the history tables. I recall reading somewhere that it's ok for there to be an overlapping ledgers because the reingestion simply overwrites the existing data, is that correct?

[tamirms]

@urvisavla during reingestion we delete rows in the history tables before we insert them:

https://github.com/stellar/go/blob/master/services/horizon/internal/ingest/fsm.go#L734