Today, I encountered a perplexing issue with ClickHouse.js. The error message "inflate failed: buffer error" left me scratching my head for a solution. If you've come across this error, you know how vague it can be. Let me share how I tackled it.

The Symptom

While working on a service called "blockhouse" which processes Ethereum blockchain data, I ran into this error:

[02:23:02.206] ERROR (42539): failed to forward. sleeping for 60s
    service: "blockhouse"
    sourceName: "EthereumRawRPCLatest"
    sinkName: "EthereumRawTables"
    version: "v1.0"
    err: {
      "type": "ClickHouseError",
      "message": "inflate failed: buffer error. ",
      ...
      "code": "354"
    }

Initially, the error message didn't give me much to work with.

Debugging Steps

To get to the bottom of this, I added some debug statements to log the counts of different datasets I was attempting to insert into ClickHouse:

console.log("DEBUG: blocks count", blocks.length);
console.log("DEBUG: transactions count", transactions.length);
console.log("DEBUG: logs count", logs.length);
console.log("DEBUG: withdrawals count", withdrawals.length);

The output revealed something interesting:

DEBUG: blocks count 100
DEBUG: transactions count 0
DEBUG: logs count 0
DEBUG: withdrawals count 0

This was a crucial clue. Despite having data in blocks, the other datasets were empty, yet attempts were made to insert them.

The Solution

The fix turned out to be straightforward: ensure that data insertion only occurs when there's actual data to insert. Here's how I adjusted the code to prevent empty inserts:

const { blocks, transactions, logs, withdrawals } = args;

const inserts = [];
if (blocks.length > 0) {
    inserts.push(
        this.config.clickHouseClient.insert({
            table: "ethereum.blocks",
            values: blocks,
            format: "JSONEachRow",
        })
    );
}

// Repeat for transactions, logs, and withdrawals
...

await Promise.all(inserts);

By checking if each dataset actually contains rows before attempting an insert, I was able to circumvent the "inflate failed: buffer error" entirely.

Key Takeaway

When working with ClickHouse.js or similar database tools, always verify your data before attempting an insert operation. Empty inserts not only waste resources but can lead to misleading and hard-to-debug errors.

I hope this walkthrough helps you avoid similar frustrations and keep your data processing smooth and error-free. Happy coding my frens!