diff --git a/store/postgres/src/deployment.rs b/store/postgres/src/deployment.rs
index 874b6e36d2b..89e1674804a 100644
--- a/store/postgres/src/deployment.rs
+++ b/store/postgres/src/deployment.rs
@@ -251,6 +251,76 @@ pub fn features(conn: &PgConnection, site: &Site) -> Result<BTreeSet<SubgraphFea
         .collect()
 }
 
+pub fn transact_block(
+    conn: &PgConnection,
+    site: &Site,
+    ptr: &BlockPtr,
+    firehose_cursor: Option<&str>,
+    full_count_query: &str,
+    count: i32,
+) -> Result<(), StoreError> {
+    use crate::diesel::BoolExpressionMethods;
+    use subgraph_deployment as d;
+
+    // Work around a Diesel issue with serializing BigDecimals to numeric
+    let number = format!("{}::numeric", ptr.number);
+
+    let count_sql = if count == 0 {
+        // This amounts to a noop - the entity count does not change
+        "entity_count".to_string()
+    } else {
+        entity_count_sql(full_count_query, count)
+    };
+
+    // Treat a cursor of "" as null; not absolutely necessary for
+    // correctness since the firehose treats both as the same, but makes it
+    // a little clearer.
+    let firehose_cursor = if firehose_cursor == Some("") {
+        None
+    } else {
+        firehose_cursor
+    };
+
+    let row_count = update(
+        d::table.filter(d::id.eq(site.id)).filter(
+            // Asserts that the processing direction is forward.
+            d::latest_ethereum_block_number
+                .lt(sql(&number))
+                .or(d::latest_ethereum_block_number.is_null()),
+        ),
+    )
+    .set((
+        d::latest_ethereum_block_number.eq(sql(&number)),
+        d::latest_ethereum_block_hash.eq(ptr.hash_slice()),
+        d::firehose_cursor.eq(firehose_cursor),
+        d::entity_count.eq(sql(&count_sql)),
+        d::current_reorg_depth.eq(0),
+    ))
+    .execute(conn)
+    .map_err(StoreError::from)?;
+
+    match row_count {
+        // Common case: A single row was updated.
+        1 => Ok(()),
+
+        // No matching rows were found. This is an error. By the filter conditions, this can only be
+        // due to a missing deployment (which `block_ptr` catches) or duplicate block processing.
+        0 => match block_ptr(&conn, &site.deployment)? {
+            Some(block_ptr_from) if block_ptr_from.number >= ptr.number => Err(
+                StoreError::DuplicateBlockProcessing(site.deployment.clone(), ptr.number),
+            ),
+            None | Some(_) => Err(StoreError::Unknown(anyhow!(
+                "unknown error forwarding block ptr"
+            ))),
+        },
+
+        // More than one matching row was found.
+        _ => Err(StoreError::ConstraintViolation(
+            "duplicate deployments in shard".to_owned(),
+        )),
+    }
+}
+
 pub fn forward_block_ptr(
     conn: &PgConnection,
     id: &DeploymentHash,
@@ -886,18 +956,7 @@ pub fn create_deployment(
     Ok(())
 }
 
-pub fn update_entity_count(
-    conn: &PgConnection,
-    site: &Site,
-    full_count_query: &str,
-    count: i32,
-) -> Result<(), StoreError> {
-    use subgraph_deployment as d;
-
-    if count == 0 {
-        return Ok(());
-    }
-
+fn entity_count_sql(full_count_query: &str, count: i32) -> String {
     // The big complication in this query is how to determine what the
     // new entityCount should be. We want to make sure that if the entityCount
     // is NULL or the special value `-1`, it gets recomputed. Using `-1` here
@@ -912,14 +971,29 @@ pub fn update_entity_count(
     // is `NULL` or `-1`, forcing `coalesce` to evaluate its second
     // argument, the query to count entities. In all other cases,
     // `coalesce` does not evaluate its second argument
-    let count_update = format!(
+    format!(
         "coalesce((nullif(entity_count, -1)) + ({count}),
                   ({full_count_query}))",
         full_count_query = full_count_query,
         count = count
-    );
+    )
+}
+
+pub fn update_entity_count(
+    conn: &PgConnection,
+    site: &Site,
+    full_count_query: &str,
+    count: i32,
+) -> Result<(), StoreError> {
+    use subgraph_deployment as d;
+
+    if count == 0 {
+        return Ok(());
+    }
+
+    let count_sql = entity_count_sql(full_count_query, count);
     update(d::table.filter(d::id.eq(site.id)))
-        .set(d::entity_count.eq(sql(&count_update)))
+        .set(d::entity_count.eq(sql(&count_sql)))
         .execute(conn)?;
     Ok(())
 }
diff --git a/store/postgres/src/deployment_store.rs b/store/postgres/src/deployment_store.rs
index d89632a049e..926a5de4636 100644
--- a/store/postgres/src/deployment_store.rs
+++ b/store/postgres/src/deployment_store.rs
@@ -1008,12 +1008,6 @@ impl DeploymentStore {
                 &block_ptr_to,
                 stopwatch,
             )?;
-            deployment::update_entity_count(
-                &conn,
-                site.as_ref(),
-                layout.count_query.as_str(),
-                count,
-            )?;
             section.end();
 
             dynds::insert(&conn, &site.deployment, data_sources, &block_ptr_to)?;
@@ -1027,13 +1021,14 @@ impl DeploymentStore {
                 )?;
             }
 
-            deployment::forward_block_ptr(&conn, &site.deployment, block_ptr_to)?;
-
-            if let Some(cursor) = firehose_cursor {
-                if cursor != "" {
-                    deployment::update_firehose_cursor(&conn, &site.deployment, cursor)?;
-                }
-            }
+            deployment::transact_block(
+                &conn,
+                &site,
+                block_ptr_to,
+                firehose_cursor,
+                layout.count_query.as_str(),
+                count,
+            )?;
 
             Ok(event)
         })?;