Class: Webhookdb::SyncTarget::DatabaseRoutine

Inherits:
Routine
  • Object
show all
Defined in:
lib/webhookdb/sync_target.rb

Overview

  • Ensure the sync target table exists and has the right schema. In general we do NOT create indices for the target table; since this table is for a client’s data warehouse, we assume they will optimize it as needed. The only exception is the unique constraint for the remote key column.

  • Select rows created/updated since our last update in our ‘source’ database.

  • Write them to disk into a CSV file.

  • Pass this CSV file to the proper sync target adapter.

  • For example, the PG sync target will:

    • Create a temp table in the target database, using the schema from the sync target table.

    • Load the data into that temp table.

    • Insert rows into the target table temp table rows that do not appear in the target table.

    • Update rows in the target table temp table rows that already appear in the target table.

  • The snowflake sync target will:

    • PUT the CSV file into the stage for the table.

    • Otherwise the logic is the same as PG: create a temp table and COPY INTO from the CSV.

    • Purge the staged file.

Instance Attribute Summary

Attributes inherited from Routine

#last_synced_at, #now, #replicator, #sync_target, #timestamp_expr

Instance Method Summary collapse

Methods inherited from Routine

#dataset_to_sync, #record

Constructor Details

#initialize(now, sync_target) ⇒ DatabaseRoutine

Returns a new instance of DatabaseRoutine.



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# File 'lib/webhookdb/sync_target.rb', line 420

def initialize(now, sync_target)
  super
  @connection_url = self.sync_target.connection_url
  @adapter = Webhookdb::DBAdapter.adapter(@connection_url)
  @adapter_connection = @adapter.connection(@connection_url)
end

Instance Method Details

#run ⇒ Object 



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# File 'lib/webhookdb/sync_target.rb', line 427

def run
  schema_name = @sync_target.schema.present? ? @sync_target.schema : @sync_target.class.default_schema
  table_name = @sync_target.table.present? ? @sync_target.table : @sync_target.service_integration.table_name
  adapter = @adapter
  schema = Webhookdb::DBAdapter::Schema.new(name: schema_name.to_sym)
  table = Webhookdb::DBAdapter::Table.new(name: table_name.to_sym, schema:)

  schema_lines = []
  schema_lines << adapter.create_schema_sql(table.schema, if_not_exists: true)
  schema_lines << adapter.create_table_sql(
    table,
    [@replicator.primary_key_column, @replicator.remote_key_column],
    if_not_exists: true,
  )
  (@replicator.denormalized_columns + [@replicator.data_column]).each do |col|
    schema_lines << adapter.add_column_sql(table, col, if_not_exists: true)
  end
  adapter_conn = adapter.connection(@connection_url)
  schema_expr = schema_lines.join(";\n") + ";"
  if schema_expr != self.sync_target.last_applied_schema
    adapter_conn.execute(schema_expr)
    self.sync_target.update(last_applied_schema: schema_expr)
  end
  tempfile = Tempfile.new("whdbsyncout-#{self.sync_target.id}")
  begin
    self.dataset_to_sync do |ds|
      ds.db.copy_table(ds, options: "DELIMITER ',', HEADER true, FORMAT csv") do |row|
        tempfile.write(row)
      end
    end
    tempfile.rewind
    adapter.merge_from_csv(
      adapter_conn,
      tempfile,
      table,
      @replicator.primary_key_column,
      [@replicator.primary_key_column,
       @replicator.remote_key_column,] + @replicator.denormalized_columns + [@replicator.data_column],
    )
    self.record(self.now)
  ensure
    tempfile.unlink
  end
end