From 5346377d17fc86325324fbf2766bbc8e040cf560 Mon Sep 17 00:00:00 2001
From: Oleksii Sholik <oleksii@sholik.dev>
Date: Wed, 11 Mar 2026 00:37:37 +0100
Subject: [PATCH 1/3] chore(sync-service): upgrade Elixir to 1.20.0-rc.3

Upgrade Elixir from 1.19.5 to 1.20.0-rc.3 while keeping Erlang/OTP
at 28.4. Fix Elixir 1.20 compatibility warnings:

- Remove 7 unused `require` statements detected by stricter checks
- Add pin operator (`^`) in bitstring size patterns (5 occurrences)
- Rename `Changes.record()` type to `Changes.row()` to avoid
  overriding new built-in `record/0` type
- Remove unreachable `:shutdown` case clause in pool.ex (caught by
  improved type inference from preceding handle_info clause)
- Use `apply/3` in telemetry.ex to avoid type checker flagging
  compile-time conditional as always-false

Also bump postgrex 0.21.1 -> 0.22.0 (with db_connection and
telemetry transitive bumps).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 .changeset/upgrade-elixir-rc.md               |  5 ++
 .tool-versions                                |  2 +-
 elixir-otp-upgrade-progress.md                | 60 +++++++++++++++++++
 packages/sync-service/Dockerfile              |  2 +-
 .../lib/electric/connection/manager/pool.ex   |  1 -
 .../lib/electric/replication/changes.ex       | 10 ++--
 .../replication/shape_log_collector.ex        |  1 -
 .../electric/shape_cache/pure_file_storage.ex | 10 ++--
 .../lib/electric/shape_cache/shape_status.ex  |  1 -
 .../shape_status/shape_db/migrator.ex         |  2 -
 .../shape_cache/shape_status_owner.ex         |  2 -
 .../lib/electric/shapes/consumer/move_ins.ex  |  2 -
 .../lib/electric/shapes/consumer/state.ex     |  1 -
 .../electric/stack_supervisor/telemetry.ex    |  2 -
 .../sync-service/lib/electric/telemetry.ex    |  2 +-
 packages/sync-service/mix.lock                |  6 +-
 16 files changed, 81 insertions(+), 28 deletions(-)
 create mode 100644 .changeset/upgrade-elixir-rc.md
 create mode 100644 elixir-otp-upgrade-progress.md

diff --git a/.changeset/upgrade-elixir-rc.md b/.changeset/upgrade-elixir-rc.md
new file mode 100644
index 0000000000..f781bfe001
--- /dev/null
+++ b/.changeset/upgrade-elixir-rc.md
@@ -0,0 +1,5 @@
+---
+'@core/sync-service': patch
+---
+
+Upgrade Elixir to 1.20.0-rc.3 and fix compatibility warnings (unused requires, bitstring pin operators, built-in type conflict, dead code). Also bump postgrex to 0.22.0.
diff --git a/.tool-versions b/.tool-versions
index c75f812127..4a14e7b1ef 100644
--- a/.tool-versions
+++ b/.tool-versions
@@ -1,5 +1,5 @@
 caddy 2.10.0
-elixir 1.19.5
+elixir 1.20.0-rc.3-otp-28
 erlang 28.4
 nodejs 24.11.1
 pnpm 10.12.1
diff --git a/elixir-otp-upgrade-progress.md b/elixir-otp-upgrade-progress.md
new file mode 100644
index 0000000000..45a35a7e05
--- /dev/null
+++ b/elixir-otp-upgrade-progress.md
@@ -0,0 +1,60 @@
+# Elixir/OTP Upgrade Progress
+
+## Versions
+
+- **Elixir**: 1.19.5 -> 1.20.0-rc.3
+- **Erlang/OTP**: 28.4 (unchanged, latest stable)
+- **Postgrex**: 0.21.1 -> 0.22.0 (to fix BitString pin operator warning in generated code)
+- **db_connection**: 2.8.1 -> 2.9.0 (transitive dependency of postgrex)
+- **telemetry**: 1.3.0 -> 1.4.1 (transitive dependency of postgrex)
+
+## Code changes required
+
+Elixir 1.20 introduces stricter compilation warnings from the set-theoretic type system and other compiler improvements. The following warnings needed to be fixed:
+
+### 1. Unused `require` statements (7 files)
+
+Elixir 1.20 now warns about unused `require` statements. Removed from:
+- `lib/electric/shape_cache/shape_status/shape_db/migrator.ex` - `require Logger`
+- `lib/electric/shape_cache/shape_status_owner.ex` - `require Logger`
+- `lib/electric/shapes/consumer/move_ins.ex` - `require Xid`
+- `lib/electric/stack_supervisor/telemetry.ex` - `require Logger`
+- `lib/electric/replication/shape_log_collector.ex` - `require Electric.Postgres.Lsn`
+- `lib/electric/shape_cache/shape_status.ex` - `require Electric.Shapes.Shape`
+- `lib/electric/shapes/consumer/state.ex` - `require LogOffset`
+
+### 2. Pin operator in bitstring size patterns
+
+Elixir 1.20 requires the pin operator (`^`) for variables used in `size(...)` within bitstring patterns. Fixed in:
+- `lib/electric/shape_cache/pure_file_storage.ex` - 5 occurrences across `append_move_in_snapshot_to_log!`, `read_tags`, and `append_move_in_snapshot_to_log_filtered!`
+
+### 3. Type `record/0` overriding built-in
+
+Elixir 1.20 introduced `record()` as a built-in type. Renamed `Changes.record()` to `Changes.row()` in:
+- `lib/electric/replication/changes.ex`
+
+### 4. Dead code detected by type inference
+
+- `lib/electric/connection/manager/pool.ex` - Removed `:shutdown` clause from case expression that could never match (already caught by a preceding `handle_info` clause at line 195)
+
+### 5. Compile-time conditional always false
+
+- `lib/electric/telemetry.ex` - Changed `Electric.telemetry_enabled?()` to `apply(Electric, :telemetry_enabled?, [])` to avoid type checker inferring the compile-time constant value
+
+## Known issues
+
+### Postgrex generated code warnings
+
+`Postgrex.Types.define` generates a type module using `Module.create`. Elixir 1.20's compiler flags two functions in the generated module as unused:
+- `Elixir.PgInterop.Postgrex.Extensions.PgSnapshot/4`
+- `Elixir.PgInterop.Postgrex.Extensions.PgLsn/4`
+
+These are arity-4 decode helper functions that exist for array/composite type decoding but are never called for these simple binary extension types. This is a postgrex compatibility issue with Elixir 1.20 that can't be suppressed from our side (the module is created via `Module.create` which doesn't preserve `@compile` attributes from pre-defined modules).
+
+This prevents `mix compile --warnings-as-errors` from passing, but the warnings are purely from generated dependency code, not from Electric's source.
+
+## Verification
+
+- `mix compile` - passes (2 warnings from postgrex generated code only)
+- `mix format --check-formatted` - passes
+- `mix test` - passes (382 doctests, 8 properties, 1443 tests, 0 failures)
diff --git a/packages/sync-service/Dockerfile b/packages/sync-service/Dockerfile
index 3df7f90457..3adc6432e2 100644
--- a/packages/sync-service/Dockerfile
+++ b/packages/sync-service/Dockerfile
@@ -1,4 +1,4 @@
-ARG ELIXIR_VERSION=1.19.5
+ARG ELIXIR_VERSION=1.20.0-rc.3
 ARG OTP_VERSION=28.4
 ARG DEBIAN_VERSION=bookworm-20260223-slim
 
diff --git a/packages/sync-service/lib/electric/connection/manager/pool.ex b/packages/sync-service/lib/electric/connection/manager/pool.ex
index 3b313c0838..578c29e386 100644
--- a/packages/sync-service/lib/electric/connection/manager/pool.ex
+++ b/packages/sync-service/lib/electric/connection/manager/pool.ex
@@ -229,7 +229,6 @@ defmodule Electric.Connection.Manager.Pool do
     state =
       case reason do
         :killed -> state
-        :shutdown -> state
         {:shutdown, exit_reason} -> %{state | last_connection_error: exit_reason}
         reason -> %{state | last_connection_error: reason}
       end
diff --git a/packages/sync-service/lib/electric/replication/changes.ex b/packages/sync-service/lib/electric/replication/changes.ex
index cd026a9e2f..1bf19a946e 100644
--- a/packages/sync-service/lib/electric/replication/changes.ex
+++ b/packages/sync-service/lib/electric/replication/changes.ex
@@ -17,7 +17,7 @@ defmodule Electric.Replication.Changes do
   @type db_identifier() :: String.t()
   @type xid() :: Xid.anyxid()
   @type relation_name() :: {schema :: db_identifier(), table :: db_identifier()}
-  @type record() :: %{(column_name :: db_identifier()) => column_data :: binary()}
+  @type row() :: %{(column_name :: db_identifier()) => column_data :: binary()}
   @type relation_id() :: non_neg_integer
 
   @typedoc """
@@ -186,7 +186,7 @@ defmodule Electric.Replication.Changes do
 
     @type t() :: %__MODULE__{
             relation: Changes.relation_name(),
-            record: Changes.record(),
+            record: Changes.row(),
             log_offset: LogOffset.t(),
             key: String.t() | nil,
             last?: boolean(),
@@ -210,8 +210,8 @@ defmodule Electric.Replication.Changes do
 
     @type t() :: %__MODULE__{
             relation: Changes.relation_name(),
-            old_record: Changes.record() | nil,
-            record: Changes.record(),
+            old_record: Changes.row() | nil,
+            record: Changes.row(),
             log_offset: LogOffset.t(),
             key: String.t() | nil,
             old_key: String.t() | nil,
@@ -258,7 +258,7 @@ defmodule Electric.Replication.Changes do
 
     @type t() :: %__MODULE__{
             relation: Changes.relation_name(),
-            old_record: Changes.record(),
+            old_record: Changes.row(),
             log_offset: LogOffset.t(),
             key: String.t() | nil,
             move_tags: [Changes.tag()],
diff --git a/packages/sync-service/lib/electric/replication/shape_log_collector.ex b/packages/sync-service/lib/electric/replication/shape_log_collector.ex
index e7f423fba5..93ac892df3 100644
--- a/packages/sync-service/lib/electric/replication/shape_log_collector.ex
+++ b/packages/sync-service/lib/electric/replication/shape_log_collector.ex
@@ -35,7 +35,6 @@ defmodule Electric.Replication.ShapeLogCollector do
 
   import Electric.Utils, only: [map_while_ok: 2, map_if_ok: 2]
 
-  require Electric.Postgres.Lsn
   require Electric.Replication.LogOffset
   require Logger
   require TransactionFragment
diff --git a/packages/sync-service/lib/electric/shape_cache/pure_file_storage.ex b/packages/sync-service/lib/electric/shape_cache/pure_file_storage.ex
index 1b0a475782..56481df5c7 100644
--- a/packages/sync-service/lib/electric/shape_cache/pure_file_storage.ex
+++ b/packages/sync-service/lib/electric/shape_cache/pure_file_storage.ex
@@ -909,8 +909,8 @@ defmodule Electric.ShapeCache.PureFileStorage do
           with {:meta, <<key_size::32, json_size::64, op_type::8, tag_count::16>>} <-
                  {:meta, IO.binread(file, 15)},
                _tags = read_tags(file, tag_count),
-               <<key::binary-size(key_size)>> <- IO.binread(file, key_size),
-               <<json::binary-size(json_size)>> <- IO.binread(file, json_size) do
+               <<key::binary-size(^key_size)>> <- IO.binread(file, key_size),
+               <<json::binary-size(^json_size)>> <- IO.binread(file, json_size) do
             {[{offset, key_size, key, op_type, 0, json_size, json}],
              {file, LogOffset.increment(offset)}}
           else
@@ -937,7 +937,7 @@ defmodule Electric.ShapeCache.PureFileStorage do
   defp read_tags(file, tag_count) do
     for _ <- 1..tag_count//1 do
       <<tag_size::16>> = IO.binread(file, 2)
-      <<tag::binary-size(tag_size)>> = IO.binread(file, tag_size)
+      <<tag::binary-size(^tag_size)>> = IO.binread(file, tag_size)
       tag
     end
   end
@@ -962,8 +962,8 @@ defmodule Electric.ShapeCache.PureFileStorage do
           with {:meta, <<key_size::32, json_size::64, op_type::8, tag_count::16>>} <-
                  {:meta, IO.binread(file, 15)},
                tags = read_tags(file, tag_count),
-               <<key::binary-size(key_size)>> <- IO.binread(file, key_size),
-               <<json::binary-size(json_size)>> <- IO.binread(file, json_size) do
+               <<key::binary-size(^key_size)>> <- IO.binread(file, key_size),
+               <<json::binary-size(^json_size)>> <- IO.binread(file, json_size) do
             # Check if this row should be skipped
             if all_parents_moved_out?(tags, tags_to_skip) or
                  Electric.Shapes.Consumer.MoveIns.should_skip_query_row?(
diff --git a/packages/sync-service/lib/electric/shape_cache/shape_status.ex b/packages/sync-service/lib/electric/shape_cache/shape_status.ex
index 51e087fa60..5ec652bf9e 100644
--- a/packages/sync-service/lib/electric/shape_cache/shape_status.ex
+++ b/packages/sync-service/lib/electric/shape_cache/shape_status.ex
@@ -20,7 +20,6 @@ defmodule Electric.ShapeCache.ShapeStatus do
 
   import Electric, only: [is_stack_id: 1, is_shape_handle: 1]
 
-  require Electric.Shapes.Shape
   require Logger
 
   @type stack_id() :: Electric.stack_id()
diff --git a/packages/sync-service/lib/electric/shape_cache/shape_status/shape_db/migrator.ex b/packages/sync-service/lib/electric/shape_cache/shape_status/shape_db/migrator.ex
index aef60795fc..8a32c8774c 100644
--- a/packages/sync-service/lib/electric/shape_cache/shape_status/shape_db/migrator.ex
+++ b/packages/sync-service/lib/electric/shape_cache/shape_status/shape_db/migrator.ex
@@ -3,8 +3,6 @@ defmodule Electric.ShapeCache.ShapeStatus.ShapeDb.Migrator do
 
   alias Electric.ShapeCache.ShapeStatus.ShapeDb
 
-  require Logger
-
   @optimization_period :timer.minutes(60)
 
   def start_link(args) do
diff --git a/packages/sync-service/lib/electric/shape_cache/shape_status_owner.ex b/packages/sync-service/lib/electric/shape_cache/shape_status_owner.ex
index bc9a3f9501..730405f836 100644
--- a/packages/sync-service/lib/electric/shape_cache/shape_status_owner.ex
+++ b/packages/sync-service/lib/electric/shape_cache/shape_status_owner.ex
@@ -12,8 +12,6 @@ defmodule Electric.ShapeCache.ShapeStatusOwner do
 
   alias Electric.ShapeCache.ShapeStatus
 
-  require Logger
-
   @schema NimbleOptions.new!(stack_id: [type: :string, required: true])
 
   def name(stack_id) do
diff --git a/packages/sync-service/lib/electric/shapes/consumer/move_ins.ex b/packages/sync-service/lib/electric/shapes/consumer/move_ins.ex
index c0c554cb70..a235bf7ffe 100644
--- a/packages/sync-service/lib/electric/shapes/consumer/move_ins.ex
+++ b/packages/sync-service/lib/electric/shapes/consumer/move_ins.ex
@@ -4,8 +4,6 @@ defmodule Electric.Shapes.Consumer.MoveIns do
   alias Electric.Postgres.Xid
   alias Electric.Postgres.SnapshotQuery
 
-  require Xid
-
   defstruct waiting_move_ins: %{},
             filtering_move_ins: [],
             touch_tracker: %{},
diff --git a/packages/sync-service/lib/electric/shapes/consumer/state.ex b/packages/sync-service/lib/electric/shapes/consumer/state.ex
index 3b51de7855..ff1a31aa79 100644
--- a/packages/sync-service/lib/electric/shapes/consumer/state.ex
+++ b/packages/sync-service/lib/electric/shapes/consumer/state.ex
@@ -11,7 +11,6 @@ defmodule Electric.Shapes.Consumer.State do
   alias Electric.ShapeCache.Storage
 
   require Logger
-  require LogOffset
 
   @write_unit_txn :txn
   @write_unit_txn_fragment :txn_fragment
diff --git a/packages/sync-service/lib/electric/stack_supervisor/telemetry.ex b/packages/sync-service/lib/electric/stack_supervisor/telemetry.ex
index 6f760a85f2..96b30a479d 100644
--- a/packages/sync-service/lib/electric/stack_supervisor/telemetry.ex
+++ b/packages/sync-service/lib/electric/stack_supervisor/telemetry.ex
@@ -1,6 +1,4 @@
 defmodule Electric.StackSupervisor.Telemetry do
-  require Logger
-
   def configure(config) do
     # Set shared OpenTelemetry span attributes for the given stack. They are stored in
     # persistent_term so it doesn't matter which process this function is called from.
diff --git a/packages/sync-service/lib/electric/telemetry.ex b/packages/sync-service/lib/electric/telemetry.ex
index 13023a4753..3cfb299873 100644
--- a/packages/sync-service/lib/electric/telemetry.ex
+++ b/packages/sync-service/lib/electric/telemetry.ex
@@ -23,7 +23,7 @@ defmodule Electric.Telemetry do
     modules = List.wrap(dependencies) |> Enum.map(&Macro.expand(&1, env))
     telemetry_code_available? = Enum.all?(modules, &Code.ensure_loaded?/1)
 
-    if Electric.telemetry_enabled?() && telemetry_code_available? do
+    if apply(Electric, :telemetry_enabled?, []) and telemetry_code_available? do
       if @log_level do
         Logger.log(
           @log_level,
diff --git a/packages/sync-service/mix.lock b/packages/sync-service/mix.lock
index a69bbed739..b77e63d96d 100644
--- a/packages/sync-service/mix.lock
+++ b/packages/sync-service/mix.lock
@@ -6,7 +6,7 @@
   "chatterbox": {:hex, :ts_chatterbox, "0.15.1", "5cac4d15dd7ad61fc3c4415ce4826fc563d4643dee897a558ec4ea0b1c835c9c", [:rebar3], [{:hpack, "~> 0.3.0", [hex: :hpack_erl, repo: "hexpm", optional: false]}], "hexpm", "4f75b91451338bc0da5f52f3480fa6ef6e3a2aeecfc33686d6b3d0a0948f31aa"},
   "combine": {:hex, :combine, "0.10.0", "eff8224eeb56498a2af13011d142c5e7997a80c8f5b97c499f84c841032e429f", [:mix], [], "hexpm", "1b1dbc1790073076580d0d1d64e42eae2366583e7aecd455d1215b0d16f2451b"},
   "ctx": {:hex, :ctx, "0.6.0", "8ff88b70e6400c4df90142e7f130625b82086077a45364a78d208ed3ed53c7fe", [:rebar3], [], "hexpm", "a14ed2d1b67723dbebbe423b28d7615eb0bdcba6ff28f2d1f1b0a7e1d4aa5fc2"},
-  "db_connection": {:hex, :db_connection, "2.8.1", "9abdc1e68c34c6163f6fb96a96532272d13ad7ca45262156ae8b7ec6d9dc4bec", [:mix], [{:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "a61a3d489b239d76f326e03b98794fb8e45168396c925ef25feb405ed09da8fd"},
+  "db_connection": {:hex, :db_connection, "2.9.0", "a6a97c5c958a2d7091a58a9be40caf41ab496b0701d21e1d1abff3fa27a7f371", [:mix], [{:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "17d502eacaf61829db98facf6f20808ed33da6ccf495354a41e64fe42f9c509c"},
   "decimal": {:hex, :decimal, "2.3.0", "3ad6255aa77b4a3c4f818171b12d237500e63525c2fd056699967a3e7ea20f62", [:mix], [], "hexpm", "a4d66355cb29cb47c3cf30e71329e58361cfcb37c34235ef3bf1d7bf3773aeac"},
   "dialyxir": {:hex, :dialyxir, "1.4.6", "7cca478334bf8307e968664343cbdb432ee95b4b68a9cba95bdabb0ad5bdfd9a", [:mix], [{:erlex, ">= 0.2.7", [hex: :erlex, repo: "hexpm", optional: false]}], "hexpm", "8cf5615c5cd4c2da6c501faae642839c8405b49f8aa057ad4ae401cb808ef64d"},
   "dotenvy": {:hex, :dotenvy, "1.1.0", "316aee89c11a4ec8be3d74a69d17d17ea2e21e633e0cac9f155cf420e237ccb4", [:mix], [], "hexpm", "0519bda67fdfa1c22279c2654b2f292485f0caae7360fe29205f74f28a93df18"},
@@ -43,7 +43,7 @@
   "pg_query_ex": {:hex, :pg_query_ex, "0.9.0", "8e34bd2d0e0eb9e8d621c4697032fad4bfba46826950d3b46904a80ab589b43a", [:make, :mix], [{:elixir_make, "~> 0.4", [hex: :elixir_make, repo: "hexpm", optional: false]}, {:protox, "~> 2.0", [hex: :protox, repo: "hexpm", optional: false]}], "hexpm", "a3fada1704fa9e2bc11ff846ad545ef9a1d34f46d86206063c37128960f4f5f5"},
   "plug": {:hex, :plug, "1.18.1", "5067f26f7745b7e31bc3368bc1a2b818b9779faa959b49c934c17730efc911cf", [:mix], [{:mime, "~> 1.0 or ~> 2.0", [hex: :mime, repo: "hexpm", optional: false]}, {:plug_crypto, "~> 1.1.1 or ~> 1.2 or ~> 2.0", [hex: :plug_crypto, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4.3 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "57a57db70df2b422b564437d2d33cf8d33cd16339c1edb190cd11b1a3a546cc2"},
   "plug_crypto": {:hex, :plug_crypto, "2.1.1", "19bda8184399cb24afa10be734f84a16ea0a2bc65054e23a62bb10f06bc89491", [:mix], [], "hexpm", "6470bce6ffe41c8bd497612ffde1a7e4af67f36a15eea5f921af71cf3e11247c"},
-  "postgrex": {:hex, :postgrex, "0.21.1", "2c5cc830ec11e7a0067dd4d623c049b3ef807e9507a424985b8dcf921224cd88", [:mix], [{:db_connection, "~> 2.1", [hex: :db_connection, repo: "hexpm", optional: false]}, {:decimal, "~> 1.5 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}, {:table, "~> 0.1.0", [hex: :table, repo: "hexpm", optional: true]}], "hexpm", "27d8d21c103c3cc68851b533ff99eef353e6a0ff98dc444ea751de43eb48bdac"},
+  "postgrex": {:hex, :postgrex, "0.22.0", "fb027b58b6eab1f6de5396a2abcdaaeb168f9ed4eccbb594e6ac393b02078cbd", [:mix], [{:db_connection, "~> 2.9", [hex: :db_connection, repo: "hexpm", optional: false]}, {:decimal, "~> 1.5 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}, {:table, "~> 0.1.0", [hex: :table, repo: "hexpm", optional: true]}], "hexpm", "a68c4261e299597909e03e6f8ff5a13876f5caadaddd0d23af0d0a61afcc5d84"},
   "protobuf": {:hex, :protobuf, "0.13.0", "7a9d9aeb039f68a81717eb2efd6928fdf44f03d2c0dfdcedc7b560f5f5aae93d", [:mix], [{:jason, "~> 1.2", [hex: :jason, repo: "hexpm", optional: true]}], "hexpm", "21092a223e3c6c144c1a291ab082a7ead32821ba77073b72c68515aa51fef570"},
   "protox": {:hex, :protox, "2.0.4", "2a86ae3699696c5d92e15804968ce6a6827a8d9516d0bbabcf16584dec710ae1", [:mix], [], "hexpm", "8ac5a03bb84da4c75d76dc29cd46008081c2068ad0f6f0da4c051093d6e24c01"},
   "remote_ip": {:hex, :remote_ip, "1.2.0", "fb078e12a44414f4cef5a75963c33008fe169b806572ccd17257c208a7bc760f", [:mix], [{:combine, "~> 0.10", [hex: :combine, repo: "hexpm", optional: false]}, {:plug, "~> 1.14", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm", "2ff91de19c48149ce19ed230a81d377186e4412552a597d6a5137373e5877cb7"},
@@ -54,7 +54,7 @@
   "ssl_verify_fun": {:hex, :ssl_verify_fun, "1.1.7", "354c321cf377240c7b8716899e182ce4890c5938111a1296add3ec74cf1715df", [:make, :mix, :rebar3], [], "hexpm", "fe4c190e8f37401d30167c8c405eda19469f34577987c76dde613e838bbc67f8"},
   "stream_data": {:hex, :stream_data, "1.2.0", "58dd3f9e88afe27dc38bef26fce0c84a9e7a96772b2925c7b32cd2435697a52b", [:mix], [], "hexpm", "eb5c546ee3466920314643edf68943a5b14b32d1da9fe01698dc92b73f89a9ed"},
   "stream_split": {:hex, :stream_split, "0.1.7", "2d3fd1fd21697da7f91926768d65f79409086052c9ec7ae593987388f52425f8", [:mix], [], "hexpm", "1dc072ff507a64404a0ad7af90df97096183fee8eeac7b300320cea7c4679147"},
-  "telemetry": {:hex, :telemetry, "1.3.0", "fedebbae410d715cf8e7062c96a1ef32ec22e764197f70cda73d82778d61e7a2", [:rebar3], [], "hexpm", "7015fc8919dbe63764f4b4b87a95b7c0996bd539e0d499be6ec9d7f3875b79e6"},
+  "telemetry": {:hex, :telemetry, "1.4.1", "ab6de178e2b29b58e8256b92b382ea3f590a47152ca3651ea857a6cae05ac423", [:rebar3], [], "hexpm", "2172e05a27531d3d31dd9782841065c50dd5c3c7699d95266b2edd54c2dafa1c"},
   "telemetry_metrics": {:hex, :telemetry_metrics, "1.1.0", "5bd5f3b5637e0abea0426b947e3ce5dd304f8b3bc6617039e2b5a008adc02f8f", [:mix], [{:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "e7b79e8ddfde70adb6db8a6623d1778ec66401f366e9a8f5dd0955c56bc8ce67"},
   "telemetry_metrics_prometheus_core": {:hex, :telemetry_metrics_prometheus_core, "1.2.1", "c9755987d7b959b557084e6990990cb96a50d6482c683fb9622a63837f3cd3d8", [:mix], [{:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}, {:telemetry_metrics, "~> 0.6 or ~> 1.0", [hex: :telemetry_metrics, repo: "hexpm", optional: false]}], "hexpm", "5e2c599da4983c4f88a33e9571f1458bf98b0cf6ba930f1dc3a6e8cf45d5afb6"},
   "telemetry_metrics_statsd": {:hex, :telemetry_metrics_statsd, "0.7.2", "a70cfaf821cb2f3ac2e767988461179add44762d1db752e74dfa0c93449b2857", [:mix], [{:nimble_options, "~> 0.4 or ~> 1.0", [hex: :nimble_options, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}, {:telemetry_metrics, "~> 0.6 or ~> 1.0", [hex: :telemetry_metrics, repo: "hexpm", optional: false]}], "hexpm", "933bb8b176b95d5088404b7137d94926b8dea9a74ef2c95d616f2740f1571c13"},

From 06ba704ab35f207bda41a7cb76099a91532152ef Mon Sep 17 00:00:00 2001
From: Oleksii Sholik <oleksii@sholik.dev>
Date: Wed, 11 Mar 2026 00:58:31 +0100
Subject: [PATCH 2/3] fixup! chore(sync-service): upgrade Elixir to 1.20.0-rc.3

- Fix unused `require Logger` in electric-telemetry (stack_telemetry.ex)
- Fix bitstring pin operator in elixir-client (postgres.ex)
- Restore `require Logger` in stack_supervisor/telemetry.ex (needed
  with MIX_TARGET=application)
- Use postgrex from git main to pick up the Elixir 1.20 unused-clause
  fix (https://github.com/elixir-ecto/postgrex/issues/760)
- Remove progress file (review feedback)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 elixir-otp-upgrade-progress.md                | 60 -------------------
 .../lib/electric/telemetry/stack_telemetry.ex |  2 -
 .../electric/client/ecto_adapter/postgres.ex  |  2 +-
 .../electric/stack_supervisor/telemetry.ex    |  2 +
 packages/sync-service/mix.exs                 |  4 +-
 packages/sync-service/mix.lock                |  2 +-
 6 files changed, 7 insertions(+), 65 deletions(-)
 delete mode 100644 elixir-otp-upgrade-progress.md

diff --git a/elixir-otp-upgrade-progress.md b/elixir-otp-upgrade-progress.md
deleted file mode 100644
index 45a35a7e05..0000000000
--- a/elixir-otp-upgrade-progress.md
+++ /dev/null
@@ -1,60 +0,0 @@
-# Elixir/OTP Upgrade Progress
-
-## Versions
-
-- **Elixir**: 1.19.5 -> 1.20.0-rc.3
-- **Erlang/OTP**: 28.4 (unchanged, latest stable)
-- **Postgrex**: 0.21.1 -> 0.22.0 (to fix BitString pin operator warning in generated code)
-- **db_connection**: 2.8.1 -> 2.9.0 (transitive dependency of postgrex)
-- **telemetry**: 1.3.0 -> 1.4.1 (transitive dependency of postgrex)
-
-## Code changes required
-
-Elixir 1.20 introduces stricter compilation warnings from the set-theoretic type system and other compiler improvements. The following warnings needed to be fixed:
-
-### 1. Unused `require` statements (7 files)
-
-Elixir 1.20 now warns about unused `require` statements. Removed from:
-- `lib/electric/shape_cache/shape_status/shape_db/migrator.ex` - `require Logger`
-- `lib/electric/shape_cache/shape_status_owner.ex` - `require Logger`
-- `lib/electric/shapes/consumer/move_ins.ex` - `require Xid`
-- `lib/electric/stack_supervisor/telemetry.ex` - `require Logger`
-- `lib/electric/replication/shape_log_collector.ex` - `require Electric.Postgres.Lsn`
-- `lib/electric/shape_cache/shape_status.ex` - `require Electric.Shapes.Shape`
-- `lib/electric/shapes/consumer/state.ex` - `require LogOffset`
-
-### 2. Pin operator in bitstring size patterns
-
-Elixir 1.20 requires the pin operator (`^`) for variables used in `size(...)` within bitstring patterns. Fixed in:
-- `lib/electric/shape_cache/pure_file_storage.ex` - 5 occurrences across `append_move_in_snapshot_to_log!`, `read_tags`, and `append_move_in_snapshot_to_log_filtered!`
-
-### 3. Type `record/0` overriding built-in
-
-Elixir 1.20 introduced `record()` as a built-in type. Renamed `Changes.record()` to `Changes.row()` in:
-- `lib/electric/replication/changes.ex`
-
-### 4. Dead code detected by type inference
-
-- `lib/electric/connection/manager/pool.ex` - Removed `:shutdown` clause from case expression that could never match (already caught by a preceding `handle_info` clause at line 195)
-
-### 5. Compile-time conditional always false
-
-- `lib/electric/telemetry.ex` - Changed `Electric.telemetry_enabled?()` to `apply(Electric, :telemetry_enabled?, [])` to avoid type checker inferring the compile-time constant value
-
-## Known issues
-
-### Postgrex generated code warnings
-
-`Postgrex.Types.define` generates a type module using `Module.create`. Elixir 1.20's compiler flags two functions in the generated module as unused:
-- `Elixir.PgInterop.Postgrex.Extensions.PgSnapshot/4`
-- `Elixir.PgInterop.Postgrex.Extensions.PgLsn/4`
-
-These are arity-4 decode helper functions that exist for array/composite type decoding but are never called for these simple binary extension types. This is a postgrex compatibility issue with Elixir 1.20 that can't be suppressed from our side (the module is created via `Module.create` which doesn't preserve `@compile` attributes from pre-defined modules).
-
-This prevents `mix compile --warnings-as-errors` from passing, but the warnings are purely from generated dependency code, not from Electric's source.
-
-## Verification
-
-- `mix compile` - passes (2 warnings from postgrex generated code only)
-- `mix format --check-formatted` - passes
-- `mix test` - passes (382 doctests, 8 properties, 1443 tests, 0 failures)
diff --git a/packages/electric-telemetry/lib/electric/telemetry/stack_telemetry.ex b/packages/electric-telemetry/lib/electric/telemetry/stack_telemetry.ex
index 6413382a94..df5b2a2c7a 100644
--- a/packages/electric-telemetry/lib/electric/telemetry/stack_telemetry.ex
+++ b/packages/electric-telemetry/lib/electric/telemetry/stack_telemetry.ex
@@ -12,8 +12,6 @@ defmodule ElectricTelemetry.StackTelemetry do
 
   alias ElectricTelemetry.Reporters
 
-  require Logger
-
   @behaviour ElectricTelemetry.Poller
 
   def start_link(opts) do
diff --git a/packages/elixir-client/lib/electric/client/ecto_adapter/postgres.ex b/packages/elixir-client/lib/electric/client/ecto_adapter/postgres.ex
index 300489557c..e2db87513f 100644
--- a/packages/elixir-client/lib/electric/client/ecto_adapter/postgres.ex
+++ b/packages/elixir-client/lib/electric/client/ecto_adapter/postgres.ex
@@ -399,7 +399,7 @@ if Code.ensure_loaded?(Ecto) do
 
     defp bitstring_literal(value) do
       size = bit_size(value)
-      <<val::size(size)>> = value
+      <<val::size(^size)>> = value
 
       [?b, ?', val |> Integer.to_string(2) |> String.pad_leading(size, ["0"]), ?']
     end
diff --git a/packages/sync-service/lib/electric/stack_supervisor/telemetry.ex b/packages/sync-service/lib/electric/stack_supervisor/telemetry.ex
index 96b30a479d..6f760a85f2 100644
--- a/packages/sync-service/lib/electric/stack_supervisor/telemetry.ex
+++ b/packages/sync-service/lib/electric/stack_supervisor/telemetry.ex
@@ -1,4 +1,6 @@
 defmodule Electric.StackSupervisor.Telemetry do
+  require Logger
+
   def configure(config) do
     # Set shared OpenTelemetry span attributes for the given stack. They are stored in
     # persistent_term so it doesn't matter which process this function is called from.
diff --git a/packages/sync-service/mix.exs b/packages/sync-service/mix.exs
index bbc2441871..79a8012554 100644
--- a/packages/sync-service/mix.exs
+++ b/packages/sync-service/mix.exs
@@ -100,7 +100,9 @@ defmodule Electric.MixProject do
         {:opentelemetry_semantic_conventions, "~> 1.27"},
         {:pg_query_ex, "0.9.0"},
         {:plug, "~> 1.17"},
-        {:postgrex, "~> 0.20"},
+        # TODO: Switch back to Hex once postgrex releases a version with the
+        # Elixir 1.20 unused-clause fix (https://github.com/elixir-ecto/postgrex/issues/760)
+        {:postgrex, github: "elixir-ecto/postgrex", ref: "e4f79427e99bb0dc86376a769fc966b98edb7dfc"},
         {:retry, "~> 0.19"},
         {:remote_ip, "~> 1.2"},
         {:req, "~> 0.5"},
diff --git a/packages/sync-service/mix.lock b/packages/sync-service/mix.lock
index b77e63d96d..d04178db32 100644
--- a/packages/sync-service/mix.lock
+++ b/packages/sync-service/mix.lock
@@ -43,7 +43,7 @@
   "pg_query_ex": {:hex, :pg_query_ex, "0.9.0", "8e34bd2d0e0eb9e8d621c4697032fad4bfba46826950d3b46904a80ab589b43a", [:make, :mix], [{:elixir_make, "~> 0.4", [hex: :elixir_make, repo: "hexpm", optional: false]}, {:protox, "~> 2.0", [hex: :protox, repo: "hexpm", optional: false]}], "hexpm", "a3fada1704fa9e2bc11ff846ad545ef9a1d34f46d86206063c37128960f4f5f5"},
   "plug": {:hex, :plug, "1.18.1", "5067f26f7745b7e31bc3368bc1a2b818b9779faa959b49c934c17730efc911cf", [:mix], [{:mime, "~> 1.0 or ~> 2.0", [hex: :mime, repo: "hexpm", optional: false]}, {:plug_crypto, "~> 1.1.1 or ~> 1.2 or ~> 2.0", [hex: :plug_crypto, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4.3 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "57a57db70df2b422b564437d2d33cf8d33cd16339c1edb190cd11b1a3a546cc2"},
   "plug_crypto": {:hex, :plug_crypto, "2.1.1", "19bda8184399cb24afa10be734f84a16ea0a2bc65054e23a62bb10f06bc89491", [:mix], [], "hexpm", "6470bce6ffe41c8bd497612ffde1a7e4af67f36a15eea5f921af71cf3e11247c"},
-  "postgrex": {:hex, :postgrex, "0.22.0", "fb027b58b6eab1f6de5396a2abcdaaeb168f9ed4eccbb594e6ac393b02078cbd", [:mix], [{:db_connection, "~> 2.9", [hex: :db_connection, repo: "hexpm", optional: false]}, {:decimal, "~> 1.5 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}, {:table, "~> 0.1.0", [hex: :table, repo: "hexpm", optional: true]}], "hexpm", "a68c4261e299597909e03e6f8ff5a13876f5caadaddd0d23af0d0a61afcc5d84"},
+  "postgrex": {:git, "https://github.com/elixir-ecto/postgrex.git", "e4f79427e99bb0dc86376a769fc966b98edb7dfc", [ref: "e4f79427e99bb0dc86376a769fc966b98edb7dfc"]},
   "protobuf": {:hex, :protobuf, "0.13.0", "7a9d9aeb039f68a81717eb2efd6928fdf44f03d2c0dfdcedc7b560f5f5aae93d", [:mix], [{:jason, "~> 1.2", [hex: :jason, repo: "hexpm", optional: true]}], "hexpm", "21092a223e3c6c144c1a291ab082a7ead32821ba77073b72c68515aa51fef570"},
   "protox": {:hex, :protox, "2.0.4", "2a86ae3699696c5d92e15804968ce6a6827a8d9516d0bbabcf16584dec710ae1", [:mix], [], "hexpm", "8ac5a03bb84da4c75d76dc29cd46008081c2068ad0f6f0da4c051093d6e24c01"},
   "remote_ip": {:hex, :remote_ip, "1.2.0", "fb078e12a44414f4cef5a75963c33008fe169b806572ccd17257c208a7bc760f", [:mix], [{:combine, "~> 0.10", [hex: :combine, repo: "hexpm", optional: false]}, {:plug, "~> 1.14", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm", "2ff91de19c48149ce19ed230a81d377186e4412552a597d6a5137373e5877cb7"},

From 2121a966b1d74d4516fa2fb88bf2dce875eba7cb Mon Sep 17 00:00:00 2001
From: Oleksii Sholik <oleksii@sholik.dev>
Date: Wed, 11 Mar 2026 01:01:45 +0100
Subject: [PATCH 3/3] fixup! chore(sync-service): upgrade Elixir to 1.20.0-rc.3

Fix mix.exs formatting.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 packages/sync-service/mix.exs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/packages/sync-service/mix.exs b/packages/sync-service/mix.exs
index 79a8012554..97b53f1761 100644
--- a/packages/sync-service/mix.exs
+++ b/packages/sync-service/mix.exs
@@ -102,7 +102,8 @@ defmodule Electric.MixProject do
         {:plug, "~> 1.17"},
         # TODO: Switch back to Hex once postgrex releases a version with the
         # Elixir 1.20 unused-clause fix (https://github.com/elixir-ecto/postgrex/issues/760)
-        {:postgrex, github: "elixir-ecto/postgrex", ref: "e4f79427e99bb0dc86376a769fc966b98edb7dfc"},
+        {:postgrex,
+         github: "elixir-ecto/postgrex", ref: "e4f79427e99bb0dc86376a769fc966b98edb7dfc"},
         {:retry, "~> 0.19"},
         {:remote_ip, "~> 1.2"},
         {:req, "~> 0.5"},