added build stuff from electric-sql

.gitignore

@@ -3,3 +3,4 @@
 *~
 /results/
 /*--*.sql
+electric-ddlx-*.sql

CHANGELOG.md

@@ -6,6 +6,7 @@ but not conststraints, indexes, triggers etc.
 Use `ddlx_alter()` to create those after the data is loaded.
 - more use of explicit casts
 - `ddlx_create_trigger()` improvements by [PegoraroF10](https://github.com/PegoraroF10), now with replica and always triggers
+- change `sysid` in some places to `oid`
 
 Version 0.22
 ------------

Makefile

@@ -19,3 +19,13 @@ $(DATA_built): ddlx.sql
 	@echo "Building extension version" $(EXT_VERSION) "for Postgres version" $(VERSION)
 	VERSION=${VERSION} ./bin/pgsqlpp $^ >$@
 
+
+.PHONY: electric
+electric: ddlx.sql
+	@echo "Generating Electric extension SQL for Postgres version" $(VERSION)
+	$(eval tmpfile := $(shell mktemp --suffix=.sql))
+	$(eval outfile = electric-ddlx-${VERSION}.sql)
+	VERSION=${VERSION} ./bin/pgsqlpp $^ > $(tmpfile)
+	elixir ./bin/electric.exs --in ${tmpfile} --out $(outfile)
+	@echo "Extension file written to " $(outfile)
+

README-electric.md

@@ -0,0 +1,48 @@
+# Building for Electric
+
+Electric maintains a fork of the original because we need a few tweaks 
+on the upstream behaviour, specifically:
+
+- Set column defaults within the `CREATE TABLE (...)` block, rather than via
+  `ALTER TABLE .. SET DEFAULT` statements after the table creation.
+
+- Define table constraints within the create table block too
+
+Both of these are to support direct PostgreSQL -> SQLite command translation.
+For example, SQLite does not support `ALTER TABLE .. SET DEFAULT` and we are
+currently very strict about the migrations that we allow on electrified tables.
+
+So it's best for our use case that tables are created in one shot, without
+additional `ALTER TABLE` commands.
+
+As PG versions progress it may be necessary to update these functions, hence
+this fork which applies our patches in the `ddlx.sql` file which has
+pre-processor statements for multiple PG version support.
+
+## Generating Electric extension SQL
+
+For the purposes of Electric, "extension" does not mean a postgresql extension.
+Electric has its own extension mechanism based on simple SQL statements,
+maintained via a basic migration system.
+
+That extension mechanism expects everything to be written within the `electric`
+pg schema. PostgreSQL allows for extensions to be relocated into any schema via
+the built-in extension mechanism. Since we can't use that, we need to be able
+to write our functions into a specific schema. 
+
+So we have a pre-processor script that prefixes all function definitions and
+calls with a `@schemaname@` prefix which we can replace when applying the sql
+to the live pg database.
+
+To generate a new "electrified" ddlx script, run the following:
+
+```
+make electric VERSION=$PG_VERSION
+```
+
+This will write a processed file to `electric-ddlx-$PG_VERSION.sql` in this
+repo.
+
+This file should be moved into the electric repo somewhere under 
+`components/electric/lib/electric/postgres/extension/migrations/$TIMESTAMP/ddlx-$PG_VERSION.sql`.
+See the existing ddlx migration version for a template.

bin/electric.exs

@@ -0,0 +1,20 @@
+{opts, _, _} = OptionParser.parse(System.argv(), strict: [in: :string, out: :string])
+source = File.read!(opts[:in])
+dest = Keyword.fetch!(opts, :out)
+
+IO.puts("Preprocessing #{opts[:in]} and writing to #{dest}")
+
+migration =
+  Regex.scan(~r/^CREATE OR REPLACE FUNCTION ([a-z_]+\()/m, source)
+  |> Enum.map(fn [_, f] -> f end)
+  |> Enum.uniq()
+  |> Enum.reduce(source, fn func, source ->
+    String.replace(
+      source,
+      func,
+      "@schemaname@.#{func}",
+      global: true
+    )
+  end)
+
+File.write!(dest, migration, [])

ddlx.sql

@@ -528,7 +528,7 @@ CREATE OR REPLACE FUNCTION ddlx_get_constraints(
  OUT is_deferrable boolean, 
  OUT initially_deferred boolean, 
  OUT regclass oid, 
- OUT sysid oid,
+ OUT oid oid,
  OUT is_local boolean)
  RETURNS SETOF record LANGUAGE sql AS $function$
  SELECT nc.nspname AS namespace, 
@@ -668,13 +668,13 @@ $function$;
 
 CREATE OR REPLACE FUNCTION ddlx_get_functions(
   regproc default null,
-  OUT sysid oid, OUT namespace name, OUT name name, OUT comment text, 
+  OUT oid oid, OUT namespace name, OUT name name, OUT comment text, 
   OUT owner name, OUT sql_identifier text, OUT language name, OUT attributes text, 
   OUT retset boolean, OUT is_trigger boolean, OUT returns text, OUT arguments text, 
   OUT definition text, OUT security text, OUT is_strict text, OUT argtypes oidvector,
   OUT cost real, OUT rows real)
  RETURNS SETOF record LANGUAGE sql AS $function$
- SELECT p.oid AS sysid, 
+ SELECT p.oid AS oid, 
         s.nspname AS namespace, 
         p.proname AS name, 
         pg_description.description AS comment,