From 87f6ae86fc97f95c84f6253baa5e857db4d76f9f Mon Sep 17 00:00:00 2001
From: Stamates <Stamates@users.noreply.github.com>
Date: Fri, 10 Aug 2018 17:12:03 -0400
Subject: [PATCH] Use CTE for optimized address transactions query

Co-authored-by: Timothy Mecklem <timothy@mecklem.com>
---
 apps/explorer/lib/explorer/chain.ex           |   9 +-
 .../lib/explorer/chain/transaction.ex         | 110 ++++++++++--------
 2 files changed, 65 insertions(+), 54 deletions(-)

diff --git a/apps/explorer/lib/explorer/chain.ex b/apps/explorer/lib/explorer/chain.ex
index 41fc47b714..7a75ab0a8e 100644
--- a/apps/explorer/lib/explorer/chain.ex
+++ b/apps/explorer/lib/explorer/chain.ex
@@ -179,13 +179,10 @@ defmodule Explorer.Chain do
       when is_list(options) do
     direction = Keyword.get(options, :direction)
     necessity_by_association = Keyword.get(options, :necessity_by_association, %{})
-    paging_options = Keyword.get(options, :paging_options, @default_paging_options)
 
-    # Added transaction.hash to order_by to force postgres to not use `transactions_recent_collated_index` for an
-    # index_scan before filtering based on the WHERE clauses (i.e. to speed up the query)
-    Transaction
-    |> order_by([transaction], desc: transaction.block_number, desc: transaction.index, asc: transaction.hash)
-    |> handle_paging_options(paging_options)
+    options
+    |> Keyword.get(:paging_options, @default_paging_options)
+    |> fetch_transactions()
     |> Transaction.where_address_fields_match(address_hash, direction)
     |> join_associations(necessity_by_association)
     |> Transaction.preload_token_transfers(address_hash)
diff --git a/apps/explorer/lib/explorer/chain/transaction.ex b/apps/explorer/lib/explorer/chain/transaction.ex
index d8e328ecd0..49ccd3ed68 100644
--- a/apps/explorer/lib/explorer/chain/transaction.ex
+++ b/apps/explorer/lib/explorer/chain/transaction.ex
@@ -3,6 +3,8 @@ defmodule Explorer.Chain.Transaction do
 
   use Explorer.Schema
 
+  import Ecto.Query, only: [from: 2, join: 5, preload: 3]
+
   alias Ecto.Changeset
 
   alias Explorer.Chain.{
@@ -334,78 +336,90 @@ defmodule Explorer.Chain.Transaction do
   to token_contract_address_hash, to_address_hash or from_address_hash from Token Transfers's table.
   """
   def where_address_fields_match(query, address_hash, :to) do
-    query
-    |> where(
-      [t],
-      t.hash in fragment(
+    join(
+      query,
+      :inner,
+      [transaction],
+      matches in fragment(
         """
-        (
-          SELECT t0.hash AS hash
-          FROM transactions AS t0
-          WHERE t0.to_address_hash = ? OR t0.created_contract_address_hash = ?
-        )
-        UNION
-        (
-          SELECT tt.transaction_hash AS hash
-          FROM token_transfers AS tt
-          WHERE tt.to_address_hash = ?
-        )
+        WITH hashes AS (
+          (
+            SELECT t0.hash AS hash
+            FROM transactions AS t0
+            WHERE t0.to_address_hash = ? OR t0.created_contract_address_hash = ?
+          )
+          UNION ALL
+          (
+            SELECT tt.transaction_hash AS hash
+            FROM token_transfers AS tt
+            WHERE tt.to_address_hash = ?
+          )
+        ) SELECT * from hashes
         """,
         ^address_hash.bytes,
         ^address_hash.bytes,
         ^address_hash.bytes
-      )
+      ),
+      transaction.hash == matches.hash
     )
   end
 
   def where_address_fields_match(query, address_hash, :from) do
-    query
-    |> where(
-      [t],
-      t.hash in fragment(
+    join(
+      query,
+      :inner,
+      [transaction],
+      matches in fragment(
         """
-        (
-          SELECT t0.hash AS hash
-          FROM transactions AS t0
-          WHERE t0.from_address_hash = ?
-        )
-        UNION
-        (
-          SELECT tt.transaction_hash AS hash
-          FROM token_transfers AS tt
-          WHERE tt.from_address_hash = ?
-        )
+        WITH hashes AS (
+          (
+            SELECT t0.hash AS hash
+            FROM transactions AS t0
+            WHERE t0.from_address_hash = ?
+          )
+          UNION ALL
+          (
+            SELECT tt.transaction_hash AS hash
+            FROM token_transfers AS tt
+            WHERE tt.from_address_hash = ?
+          )
+        ) SELECT * from hashes
         """,
         ^address_hash.bytes,
         ^address_hash.bytes
-      )
+      ),
+      transaction.hash == matches.hash
     )
   end
 
   def where_address_fields_match(query, address_hash, nil) do
-    query
-    |> where(
-      [t],
-      t.hash in fragment(
+    join(
+      query,
+      :inner,
+      [transaction],
+      matches in fragment(
         """
-        (
-          SELECT t0.hash AS hash
-          FROM transactions AS t0
-          WHERE t0.to_address_hash = ? OR t0.from_address_hash = ? OR t0.created_contract_address_hash = ?
-        )
-        UNION
-        (
-          SELECT tt.transaction_hash AS hash
-          FROM token_transfers AS tt
-          WHERE tt.to_address_hash = ? OR tt.from_address_hash = ?
-        )
+        WITH hashes AS (
+          (
+            SELECT t0.hash AS hash
+            FROM transactions AS t0
+            WHERE t0.to_address_hash = ? OR t0.from_address_hash = ? OR t0.created_contract_address_hash = ?
+          )
+          UNION ALL
+          (
+            SELECT tt.transaction_hash AS hash
+            FROM token_transfers AS tt
+            WHERE tt.to_address_hash = ? OR tt.from_address_hash = ?
+          )
+        ) SELECT * from hashes
         """,
         ^address_hash.bytes,
         ^address_hash.bytes,
         ^address_hash.bytes,
         ^address_hash.bytes,
         ^address_hash.bytes
-      )
+      ),
+      transaction.hash == matches.hash
     )
   end