Mirror gives you the flexibility to ELT (extract > load > transform) your data, or ETL it. In other guides we focus on the ELT use-case; here we’ll walk through an ETL example considering Uniswap swaps.

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What you’ll need

  1. A high-level understanding of Uniswap’s contract design, namely the factory > pool process.
  2. A destination to write your data to; for this use case specifically we recommend a Postgres sink.

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Walkthrough

1

Write logic to collect Uniswap pool contract addresses

In order to find all Uniswap swap events across pools, we need to know all Uniswap pool contract addresses.Here, we’re using Base as an example, and can find the relevant UniswapV3Factory deployment address from Uniswap’s docs.We can use Mirror to watch the factory for PoolCreated() events against the factory address; the SQL logic to do this using Goldsky’s decoded event logs schema is below.
SELECT
    lower(event_params[5]) AS contract_address
FROM
    base.decoded_logs
WHERE
    address = lower('0x33128a8fC17869897dcE68Ed026d694621f6FDfD')
    AND event_signature = 'PoolCreated(address,address,uint24,int24,address)'
2

Write logic to collect trades

Next, we need to define the logic to filter the decoded logs database for Uniswap Swap() events, and we can use the logic written above as a subquery to filter only for Uniswap pool events (so that we filter out other contracts that emit similar Swap() events from our stream).We need to add STATE_TTL hints in order to prevent all the logs from being kept.

SELECT
  id,
  raw_log.block_number AS block_num,
  raw_log.block_timestamp AS block_time,
  transaction_hash AS tx_hash,
  'base' as chain,
  address,
  event_params[1] AS sender,
  event_params[2] AS receiver,
  event_params[3] AS amount0,
  event_params[4] AS amount1,
  event_params[5] AS price,
  event_params[6] AS liquidity,
  event_params[7] AS tick
FROM
  base.decoded_logs
WHERE
  event_signature = 'Swap(address,address,int256,int256,uint160,uint128,int24)'
  AND address IN (
    SELECT
      lower(event_params[5]) AS contract_address
    FROM
      base.decoded_logs
    WHERE
      address = lower('0x33128a8fC17869897dcE68Ed026d694621f6FDfD')
      AND event_signature = 'PoolCreated(address,address,uint24,int24,address)'
  );
3

Write full pipeline configuration

Now that we have the core logic for our streaming transformation written, we can combine it into a Mirror pipeline configuration file. As a refresher, the high-level outline for a pipeline configuration is as follows.
overview.yaml
name: <pipeline-name>
apiVersion: 3
sources:
transforms:
sinks:
We’ll one-line the SQL from the previous step, and write out a full configuration file.
config.yaml
name: uniswap-trades
apiVersion: 3
sources:
  my_base_decoded_logs:
    dataset_name: base.decoded_logs
    version: 1.0.0
    type: dataset
    start_at: earliest
transforms:
  univ3swaps:
    sql: |
      SELECT
        id,
        raw_log.block_number AS block_num,
        raw_log.block_timestamp AS block_time,
        transaction_hash AS tx_hash,
        'base' as chain,
        address,
        event_params[1] AS sender,
        event_params[2] AS receiver,
        event_params[3] AS amount0,
        event_params[4] AS amount1,
        event_params[5] AS price,
        event_params[6] AS liquidity,
        event_params[7] AS tick
      FROM
        my_base_decoded_logs
      WHERE
        event_signature = 'Swap(address,address,int256,int256,uint160,uint128,int24)'
        AND address IN (
          SELECT lower(event_params[5]) AS contract_address
          FROM my_base_decoded_logs
          WHERE address = lower('0x33128a8fC17869897dcE68Ed026d694621f6FDfD')
          AND event_signature = 'PoolCreated(address,address,uint24,int24,address)'
        );
    primary_key: id
sinks:
  ethereum_1155_sink:
    type: postgres
    table: base_univ3_swaps
    schema: public
    secret_name: <YOUR_SECRET>
    from: univ3swaps
4

Deploy pipeline

Once we have our pipeline.yaml configuration file, we can deploy from CLI with a single line of code:
goldsky pipeline apply config.yaml
After a minute or so, the Mirror pipeline will start walking through the decoded logs. You can monitor the progress of the pipeline by monitoring the max(block) in the database against a block explorer.You can speed up the backfill by upscaling the resource size (and then scale back down to an S worker at edge). An M pipeline caught up to edge (~600K swaps as of October 2023) in approximately 45 minutes.
5

Create stream for other chains (or one multi-chain stream)

Once you’ve iterated on a single-chain use case (with the exact schema, sink indexes, etc that you need), you can update your pipeline configuration to write multiple chains’ worth of Uniswap data in one. You’d simply add additional sources/transforms/sinks in your config, replacing the referenceName and deployment addresses for each chain.
Can't find what you're looking for? Reach out to us at support@goldsky.com for help.