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Solana Blocks API

The Blocks cube is the chain's clock. Use it to convert a slot to a timestamp, watch the chain tip, measure throughput, or detect skipped slots.

Block {
  Slot          the slot this block occupies
  Height        block height (not the same number as Slot, see below)
  ParentSlot    the slot of the previous block
  Time          block timestamp
  Date          block date
  Hash          block hash
  ParentHash    previous block hash
  TxCount       transactions in the block
  RewardsCount  reward entries in the block
}

Slot is not height​

This trips people up constantly, so it is worth stating plainly: on Solana Slot and Height are different numbers, and the gap between them grows over time.

A slot is a scheduled time window for a leader to produce a block. When a leader fails to produce one, the slot is skipped: no block ever exists at that slot, and height does not advance. Height counts blocks that exist; slot counts opportunities that were scheduled.

If you are storing "block number" for Solana, decide which one you mean. Anything time-based should key on Slot, since it maps to the network's schedule. Anything counting blocks should use Height.

Latest blocks​

query LatestSolanaBlocks {
  Solana {
    Blocks(limit: { count: 10 }, orderBy: { descending: Block_Slot }) {
      Block {
        Slot
        Height
        ParentSlot
        Time
        TxCount
        RewardsCount
        Hash
      }
    }
  }
}

Stream the chain tip​

Blocks is one of the cleaner streams to consume: one message per block, at Solana's block cadence, with no filter required.

subscription SolanaChainTip {
  Solana {
    Blocks {
      Block {
        Slot
        Height
        Time
        TxCount
        ParentSlot
      }
    }
  }
}

Useful as a heartbeat. If this stream goes quiet, the problem is your connection or the network, not your filter, which is a helpful thing to be able to distinguish when a busier subscription stops delivering.

Detect skipped slots​

Slot - ParentSlot is 1 when no slot was skipped. Anything larger means the leader for those slots produced nothing.

subscription SkippedSlots {
  Solana {
    Blocks {
      Block {
        Slot
        ParentSlot
        Time
      }
    }
  }
}

Compute the gap client-side:

const skipped = Number(block.Slot) - Number(block.ParentSlot) - 1;
if (skipped > 0) console.log(`${skipped} slot(s) skipped before ${block.Slot}`);

A rising skip rate means leaders are failing to produce, which usually shows up as degraded confirmation times before it shows up anywhere else. It is a cheap network-health signal, and one you cannot get from trade or transfer data.

Look up the timestamp for a slot​

query SlotToTime {
  Solana {
    Blocks(limit: { count: 1 }, where: { Block: { Slot: { eq: "436918084" } } }) {
      Block {
        Slot
        Height
        Time
        TxCount
      }
    }
  }
}

Replace the slot with the one you are looking up.

An empty result usually means retention, not a bad slot

If a slot returns no rows, it is most often outside the history your plan retains rather than a slot that does not exist. Check a recent slot first to confirm the query shape, then widen. A genuinely skipped slot also returns nothing, so the two cases look identical — use ParentSlot on the surrounding blocks to tell them apart.

Throughput per day​

TxCount aggregates, so block and transaction throughput is one query rather than a scan over transactions.

query SolanaDailyThroughput {
  Solana {
    Blocks(limit: { count: 14 }, orderBy: { descending: Block_Date }) {
      Block {
        Date
      }
      blocks: count
      transactions: sum(of: Block_TxCount)
      rewards: sum(of: Block_RewardsCount)
    }
  }
}

Dividing transactions by blocks gives average transactions per block, which is a better load measure than raw TPS because it is not distorted by skipped slots.